CA1143056A - Broad-band antenna systems - Google Patents
Broad-band antenna systemsInfo
- Publication number
- CA1143056A CA1143056A CA000327075A CA327075A CA1143056A CA 1143056 A CA1143056 A CA 1143056A CA 000327075 A CA000327075 A CA 000327075A CA 327075 A CA327075 A CA 327075A CA 1143056 A CA1143056 A CA 1143056A
- Authority
- CA
- Canada
- Prior art keywords
- coupling transformer
- primary winding
- winding
- coupling
- antenna
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
- H01Q1/38—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith formed by a conductive layer on an insulating support
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q11/00—Electrically-long antennas having dimensions more than twice the shortest operating wavelength and consisting of conductive active radiating elements
- H01Q11/12—Resonant antennas
- H01Q11/14—Resonant antennas with parts bent, folded, shaped or screened or with phasing impedances, to obtain desired phase relation of radiation from selected sections of the antenna or to obtain desired polarisation effect
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
- H01Q5/20—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements characterised by the operating wavebands
- H01Q5/25—Ultra-wideband [UWB] systems, e.g. multiple resonance systems; Pulse systems
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
- H01Q5/50—Feeding or matching arrangements for broad-band or multi-band operation
Abstract
Abstract of the Disclosure A broad-band antenna system suitable for re-ception in the VHF and UHF television bands comprises a compact antenna unit having a configuration which provides an electrically symmetrical non-radiating linear receptor;
and a low impedance non-reactive transmission line and load coupler connected to the antenna and load.
and a low impedance non-reactive transmission line and load coupler connected to the antenna and load.
Description
~3~56 BROAD-BAL~D ANTENN~ SYST~MS
Abstract of the Disclosure A broad-band antenn~ system suitable for re-ception in tne VHF and UEF television bands comprises a compact antenna unit having a configuration which provides an electrically symmetr~cal ncn-radiating lir.~ar receptor;
and a low impedance non-reactive transmlssion line and load coupler connected ~o the antenna ar.d loa~.
Bac~ground of the Invention This invention relates to antenna systems for the recep~ion o~ elect_omagnetic waves, and more ,oarticula~ly, to compact and e~fective ar.tenna systems capable of ef1cienr-~ly intercepting VHF or UHF signais of the fre~uencies llsed in television and FM radio broadcasting, and transferring ~hem to the input of a si~nal conversi3n device. In general, ~he present inven.ion relates to antenna systems in which the r~ceptor appears to be electrostaticall~ rather than in-ductiv~ly responsive, and ls coupled to a lcw impedance, re-sistively texminated transmission l~ne.
Numerous ~ntenna configurltions have heretofore ~een proposea, consisting in general GL di~oles, 120p5~ _r long~wire ty~e devices, and var 3tions cr c~m~inatior.s c,~
them. For VEE and UEF recep~ion, ~-arlous rorms o,~ dipol s are today used aLmGst exclusively; loops are also used ~-or 3~ 6 VHF as well as often used for directlon finders, or in com-bination with ferrite rods for ~ broadcast reception.
As is well-known, transmitting antennas radiat2 a combined ield of electric and magnetic energy, and the interchange of energy in the two flelds results in a compo~ite field of energy commonly identified ~s an electromag~etic wave in the far zone (i.e., se~eral wavelengths away from the transmitting antenna). This wave may be vi~ualized as a spherical or isotropic field when radiated in free space from an antenna ideally coupled to the characteristic lmpe-- dance (120 pi) of free space. At distances comparable to those of a typical rv receiver, the electromagnetic wa~e f_ont is only a s~all area se~ment of the outer boundaries of the isotropic field o energy. Thus, a signal appears to a re-mote antenna as a plane wave whose electric and magnetic ~ields are 90 apart and perpendicular to the direction of travel of the wave front.
The design of the dipole and loop families of an-tenna is predicated on ~hese kno~n characteristics of elec-tromagnetic wave propagation. Dipoles utilize the energy of both the electric and magnetic fields, so that currents are inducad in the antenna elements, and voltage gradients are established as functions or the dimensions of the antenna with respect to the wavelengths o the incident signals.
- A dipole is characteristically a basicaily -eso-nant narrow-~and device, with a marked bi-directional pattern.
For optimum erficiency, therefore, it must be tuned ar.d ac-curately directed. TypicallY, as a result o~ their electro masnetic ~roperties, rec~ ing dipoles also exhibit substan-~.~43~6 tial reradiation of the incident field with attendant energy lOas to their surroundings. Means such as parasitic elements, reflectors and directors are often used with broad-band folded dipoles to provide, to the extent feasible, multiple modec of resonance to cover the desired frequency apectrum, and to recapture reradiated energy resulting from current ~low in the antenna elements. ~he extent of reradiation is a mea-sure of the inefficiency of known dipoles.
In contrast to dipoles, loop antennas are essential-ly magnetic field recei~ing devices, the sensitivity o~ whlch is a function of area and the number of turns. ~hey must of necessity be physically larger than the present in~ention.
Moreover, like dipoles, but unlike the present inventior, loop antennas suffer significant losses due to reradiation, because they are closed circuits in which current flow is sought to be maximized.
Among the numerous known prior art patents directed to antenna configurations or systems are: United States Nos.
Abstract of the Disclosure A broad-band antenn~ system suitable for re-ception in tne VHF and UEF television bands comprises a compact antenna unit having a configuration which provides an electrically symmetr~cal ncn-radiating lir.~ar receptor;
and a low impedance non-reactive transmlssion line and load coupler connected ~o the antenna ar.d loa~.
Bac~ground of the Invention This invention relates to antenna systems for the recep~ion o~ elect_omagnetic waves, and more ,oarticula~ly, to compact and e~fective ar.tenna systems capable of ef1cienr-~ly intercepting VHF or UHF signais of the fre~uencies llsed in television and FM radio broadcasting, and transferring ~hem to the input of a si~nal conversi3n device. In general, ~he present inven.ion relates to antenna systems in which the r~ceptor appears to be electrostaticall~ rather than in-ductiv~ly responsive, and ls coupled to a lcw impedance, re-sistively texminated transmission l~ne.
Numerous ~ntenna configurltions have heretofore ~een proposea, consisting in general GL di~oles, 120p5~ _r long~wire ty~e devices, and var 3tions cr c~m~inatior.s c,~
them. For VEE and UEF recep~ion, ~-arlous rorms o,~ dipol s are today used aLmGst exclusively; loops are also used ~-or 3~ 6 VHF as well as often used for directlon finders, or in com-bination with ferrite rods for ~ broadcast reception.
As is well-known, transmitting antennas radiat2 a combined ield of electric and magnetic energy, and the interchange of energy in the two flelds results in a compo~ite field of energy commonly identified ~s an electromag~etic wave in the far zone (i.e., se~eral wavelengths away from the transmitting antenna). This wave may be vi~ualized as a spherical or isotropic field when radiated in free space from an antenna ideally coupled to the characteristic lmpe-- dance (120 pi) of free space. At distances comparable to those of a typical rv receiver, the electromagnetic wa~e f_ont is only a s~all area se~ment of the outer boundaries of the isotropic field o energy. Thus, a signal appears to a re-mote antenna as a plane wave whose electric and magnetic ~ields are 90 apart and perpendicular to the direction of travel of the wave front.
The design of the dipole and loop families of an-tenna is predicated on ~hese kno~n characteristics of elec-tromagnetic wave propagation. Dipoles utilize the energy of both the electric and magnetic fields, so that currents are inducad in the antenna elements, and voltage gradients are established as functions or the dimensions of the antenna with respect to the wavelengths o the incident signals.
- A dipole is characteristically a basicaily -eso-nant narrow-~and device, with a marked bi-directional pattern.
For optimum erficiency, therefore, it must be tuned ar.d ac-curately directed. TypicallY, as a result o~ their electro masnetic ~roperties, rec~ ing dipoles also exhibit substan-~.~43~6 tial reradiation of the incident field with attendant energy lOas to their surroundings. Means such as parasitic elements, reflectors and directors are often used with broad-band folded dipoles to provide, to the extent feasible, multiple modec of resonance to cover the desired frequency apectrum, and to recapture reradiated energy resulting from current ~low in the antenna elements. ~he extent of reradiation is a mea-sure of the inefficiency of known dipoles.
In contrast to dipoles, loop antennas are essential-ly magnetic field recei~ing devices, the sensitivity o~ whlch is a function of area and the number of turns. ~hey must of necessity be physically larger than the present in~ention.
Moreover, like dipoles, but unlike the present inventior, loop antennas suffer significant losses due to reradiation, because they are closed circuits in which current flow is sought to be maximized.
Among the numerous known prior art patents directed to antenna configurations or systems are: United States Nos.
2~039t988~ is~ued May 5, 1936, to Graves, Jr.; 2,166,750, issued July 18, 1939, to Carter, 2,648,001, issued August 4, 1953, to Rowland, 2,761,140, issued August 28~ 1956, to Ashton;
2,821,710 issued January 28~ 1958, to ~ale; 2,990,547 issued June 27, 1961, to McDougal; 3 rl67 ~775 ~ issued January 26, 1965, to C-uertle_; 3,231,89~, issued January 25, lg66, to Nagai; 3,344,425, issuecL September 26~ 1367, to Webb; 3,454,951 issued July 8, 1969, to ~atterson, et al.; 3~689~929~ issued September 5, 172, to Mo~dy; and 3,7}6,861, issued Fe~ruary 13, 1973~ to ~oot; ~nd G2rman palent No. 1~019~717~ issued Novem-ber 21, 1957~ to Kathrein.
~3i~S~
Each of the foregoing patents, among numero-ls others, relates to a proposed antenna with points of super~icial simi-larity to aspects of the applicant's antenna syst~m, but none discloses the applicant's antenna structure or appears capable of realizing the operative advant~ges of the present system.
For example, although it is suggested in U.S. Patent No.
2,821,710 issued January 28~ 1958, to ~ale; 2,990,547 issued June 27, 1961, to McDougal; 3 rl67 ~775 ~ issued January 26, 1965, to C-uertle_; 3,231,89~, issued January 25, lg66, to Nagai; 3,344,425, issuecL September 26~ 1367, to Webb; 3,454,951 issued July 8, 1969, to ~atterson, et al.; 3~689~929~ issued September 5, 172, to Mo~dy; and 3,7}6,861, issued Fe~ruary 13, 1973~ to ~oot; ~nd G2rman palent No. 1~019~717~ issued Novem-ber 21, 1957~ to Kathrein.
~3i~S~
Each of the foregoing patents, among numero-ls others, relates to a proposed antenna with points of super~icial simi-larity to aspects of the applicant's antenna syst~m, but none discloses the applicant's antenna structure or appears capable of realizing the operative advant~ges of the present system.
For example, although it is suggested in U.S. Patent No.
3,716,861 that Ln a loop antenna (which the applicant's is not) "...a serpentine configuration" may increase capacitive reactance and radiation resistance, no suggestion is to be found for a configuration like that of the present invention in which reradiation and its attendant losses are minlmized.
So, too, in the matter of directionality, which, according to the disclosure of that patent is to be controlled by the disposition of the undulations or by the size of the undula-tions, the surprisingly non-directional characteristics at-taina~le with the applicant's system are not suggested.
The present invention has, therefore, as its prin-cipal o~ject, the provision of a compact high efriciency broad-ba~d antenna system, the characteristics of ~ich are substan-tially omni-directional, but which, as will be shown, has a sharp null zone, which may ~e used to reduce undesired in-terference levels.
The foregoing and other objects are realized, in a presently p~eferred for~ of ~he in~ention, by a sys'em wh_ch employs a novel complement of a multi-resonant su~stantially non-reradiating receptor and output matching load coupler and a low VSWR transmission line and signal conversion load coupler.
In a presently ~referred form of the invention, 3`{~7~6 the receptor has a plurality of individual segments disposed in a s~etrical array, the sesments being wire-like conduc-tive members, sinuous ln configuration. The sesments may ~e conceptualized as consisting of a series of multi-resonant folded monopolar elements connected in series~ The conductors defining the segments and their elements are of small cross-sectional dimension, i~ having been found that, in general, the smaller the cross-section of the conductors and the more closely they are spaced the more satisfactory the performance of the antenna. Although, consistent with the principles of the invention, the conductors may be wire, or preferably, created by printed circuit techniques, they are sometimes referred herein as "wire-like" to signify their small cross-sectional area, and their tight-folded loop configuration so as to distinguish them rrom large self-supporting antenna-forming elements such as tubing or castings.
The electrically symmetrical receptor apparently presents to the sending end of the transmission line vi~ the coupler system a broad-~and frequency response and impedance comparable to that of ~ree space, i.e., 120 pi. The sending end of the transm~ssion line in the presently preferred em-bodLment consists of a series loading coil which is connected to the receptor at the electrical center point of the receptor, and îs both elac~r~cally and inductively coupled to the low Lmpedance low VSWR transmission line.
SLnce the present receptor is electrically symmet--rical with respect to its feed point, it is relatively insen-sitive to the magnetic component of the eiectromasnetic field.
Under these conditions a very ~mall RF surface current lows ~3~ 6 on the receptor, and consequently does not result in a signi-ficant reradiation of the field received. Any curr~nts which result from the a~sorption of ~he electric field will appear at the common junction point of the two halves of the receptor, in phase relationships which vary with frequency, due to the multi-resonant modes of the interconnec~ing monopoles, there-by reducing the magnitude of the current flow in ~he receptor elements and raising its radiation resistance to a point where, it is believed, the receptor becomes essentially a bridging source of energy between the transmission line coupling system and free space.
For the purpose of illustrating the invention, there are shown in the drawings forms of the invention which ~re presently preferred, it being understood, however, that this invention is not limited to the precise arrang~ments and in-str~entalittes shown.
Figure 1 is a circuit schematic drawing of an anten-na system in accordance with the invent~`on, in an embodiment using a conventional 300 ohm twin lezd transmission line.
Figure 2 is a circuit schematic drawing showing a modified form of antenna system in accordance with the in-vention, in an ~mbodiment using a conventional low impedance coaxial transmission line.
Figure 3 is a plan ~ie~, in approximately full scale, illustr ting an embodim~nt of ar antenna means or receptor ~or use in an antenna system in accordanc~ wi~h ~Ihe present invention.
Figure 4 is a side elevatio~ Yiew of the embodiment of Figure 3, depicting somewhat diagrammat-cally ~not to scale) ~3~5~
t~e relationship between the segments and the substrate on which they are supported.
Figure 5 is a pictorial view of an zntenna means or receptor in accordance with the inven~ionO
Figure ~ is a pic~orial view of a core upon which the antenna load inductors and transmission line couplers may ~e wound in accordance with the invention.
~3~3S6 D ~
Reerring now to the drawinss in de~ail, wherein like numerals indicate like elements, there is seen in Figure 1 an antenna system designated generally by the reference numeral 10..
The antenna system 10 comprises antenna means, d~sig-n~ted yenerally by ~he reference numeral 12, in the form of a multi-resonant, subst~ntially non-radiating electrically symmetrical receptor (which will ~e described in greater de-tail below); and signal transmission means, designated gen-erally by the reference numeral 14y for coupling the antenna means 12 to a load.
The transmission means 14 in the form of the in~en tion illustrated in Figure 1 comprises a balanced transmission line 16 of the parallel conductor (300 ohm~ type, and having conductors 18 and 20; a coupling transformer designated gen-eraLly by the reference numeral 22 connected to the antenna means 12 and the transmission line 14; and another coupling transformer, designated generally by the refe~ence numeral 24 connected to the transmlssion line 16 and an input terminal of a load or dri~en de~ice ~designated by the symbol "L")~
The coupling transformer 22 has a prima~y winding in the form or an inductor Ll, which is connected to ~he an-tenna means 12 as a loading coil at the electrical center ~Ic~ of the antenna means 12. In one presently contemplatad form of the in~ention, the inductor Ll can be made integral with the antenna means 12, as will De explained ~elow.
3~6 The secondary winding of ~he coupling transformer 22 comprises a pair of like-wound series-connected coils or inductors L2 and L3, having e~ual numbers of t~lrns, each ln-ductively coupled to the inductor Ll. The mductor Ll is also electrically connected ~o the secondary winding, its ~inish being connected to the junction "d" of L2 and L3, that junction being, in ~iew of the values of L2 and L3, the elec-trical center of the secondary winding. In one present form of the coupling transformer 2~, the number of turns in the inductor Ll is in the ratio of 2:1 with the number of turns in each of the inductors L2 and L3.
The conductQrs 18 and 20 of the t~ansmission line 16 are connected, respecti~ely, at their antenna ends to ~he start 7'e" and finish "f" of the secondary windings. The oth~r ends of the conductors 18 and 20 are connected, respectively, at junctions "g" and "h'l to the primary windings of the couplins transformer 24.
The primary windings of the coupling transformer 24 comprise li.ke-wound sexies-connected coils or inductors L4 and L5, having equal numbers of turns, and the secondary windings comprise an inductor L6. In one present form of the coupling transformer 24, the num~er of turns ln each of the inductors L4 and L5 is i~ the ratio of 2:1 with ~he number of turns in ~he inductor L6. A conductor 26 connects the electrical center "i" of the pr~mary windings L4, L5 and ~e finish of inductor L6.
The manner of oper~tion o ~he antenna system 10 should ncw ~e apparent.
The electrcmagnetic field is in~ercepted by ~e .
antenna means 12, causing a cuxrent to flow, the current and voltage being in phase at point "c" and the voltage a maximum at points "a" a~d "b". The in-phase voltage and current of point "c" (the electrical center of the antenna means 12) produces a resultant current Il ~hrough inductor Ll. The current Il is equally divided at junction "d", half goins through L2 and conductor 2~ and half through inductor L3 and conductor 18, and remains divided until it reaches the junc-tion "i" of inductors L4 and L5. The preceding conditions obtain, when the antenna is optimall~ directed toward the transmitting station.
It will be recognized that current Il, meets only one ~ignificant impedance, namely, Ll, since the equal com-ponents of Il, in L2 and L3 produce equal voltages of the same phase at junctions "e" and "f". The point "i", at which the halves of current Il, rejoin, is the electrical center of the primary winding of coupling transformer 24, and is at g~ound po1:ential, the conductor 26 being connected to the grounded input termlnal of the load through point ";". As a result of mutual inductance, the halves of Il produce equal voltages of opposite phase at points "g" and "h", so no com-ponent of current Il is induced in inductor L6. In signal conversion de~ices ha~ing an unbalanced input, i.e. either input terminal grounded, the finish end of L6 point "j" would be connected to th~ grounded terminal.
Current Il do~g generate, howe~er, by mutual induc-tion, a current I2 which flows in the circuit consisting of inductors L2 and L3, transmission line 16 ~conductors 18 and 5~
20~, and inductors L4 and L5. The current I2 induces by coupling between inductors L4 and L5 a current I3 in inductor L6, thus producing a ~oltage "v" across the input of the receiver input load.
The advantage of this syst~m is that perfect symmet~y occurs from point "c" to point "i", resulting in a minimum reactive transmission line with a minimum VSWR and broad b~r.d resistive termination.
In the presently contemplated best mcde of carryir.g out the present invention, the inductors Ll, L2 and L3 are wound from equal lengths of very fine wire, twisted together to interwind them with approximately 15 twists per inch and tightly wound into a very small coil with the start of L2 and the fini~h of L3 forming the above-mentioned junction at "d". The finish of Ll is al50 terminated at "di'.
Th~! impedance of Ll can be raised 2S desired by adding a fourth wire, not shown in the drawing, twisted to-geth~r with the three other wires to form a series aiding coil. When Ll is made up of two wires, the finish of one wire is connected to the start of the second wire and the finish of the second wire is connected to junction "d". When the antenna means 12 has relatively chort conductor lengths, the enhanced inductance of the thus-modified inductor Ll pro-duces ~he higher imped nce matching coupling required for a smaller electric dipole.
Winding of the inductors Ll, L2 and L3 Gn a suit-able high permeabllity core, such as is illustrated in Figure 6, can reduce the capacitance between turns by reducing the amount of wire needed to zttain the desired inductance. This 3~56 results in a better Lmpeda~ce match at VHF and a more uniform response in the UHF range. In the presently prefe~red form of the invention, the inductors are simultaneously quadrifllar, trifilar or bifilar wound on the twin hole balun core desig-nated in Figure 6 by the rererence numeral 23, there being approximately one and one-half (l-l/2) turns in each of the coils, and the transformer having an impedance transformation ratio of 2:1. The core for the coupling transformer 22 in the presently pxeferred form includes a pair of spaced parallel bores 25 and 27 for receiving the wires forming inductors L2 and L3, and the wires forming inductors Ll, L2 and L3 are wound around the core 23. Winding in this manner ensures the desired ~ery tight coupling with minimum leakage reactance between inductors such as L2 and L3 and L4 and L5.
The core material presently preferred is a ferroxide made and sold by ~rystinel Corp., of Port Chester, New York, and designated "~-405" with a nominal permeability (mu) of 370. In an operatlve embodiment, ~he core is .001 i~. hlgh, ~141 in. wide and .079 in~ long, and the bores 25 and 27 re .031 in. in diameter. The important properties of the core material for V~/U~E applications ar~ its permeability and "Q", the product of which will be recognized as a measure of inZuctive efficiency~
Referrlng now to Figure 2, there i5 seen a mod fied form of antenna system wherein elements corresponding to those previ~usly described are designated b~ like, pri,~ed reference numerals.
The embodiment of the invention depicted in Figure 2 utilizes an unbalanced coaxial tr~nsmission line 16' (con-~ ~3;~5~
ventionally of 75 ohms though other impedances may be used).
Such transmission lines offer some advantages when used with recPivers having poor signai balance at their input terminals, or which radiate spurlous oscillations which disturb the in-cident sig~al on an open line.
The finish of inductor Ll is connected to the start of inductor L~ at point "d"'. The shield 28 of the transmission line 16' is connected to the finish of inductor L~ at point "e "', and the center wire 20 of the transmission line 16' to point "d"'. Current I2 induced in inducto L2, passes through inductor L7 to the transmlssion line shield 28.
Current I~ travels directly through inductors Li and L2 to the shield 28 at point "e "' and subsequently to point "k", the common terminal of inductors L7 and Llo, which are inductively coupled~ respectively, to windings L8, Lg, Lll and L12 of the coupling transformers 24' and 24", the wlndings comprising liXe-wound inductors of equal value. No current will be induced in inductor L8 and inductor L9 ex-cept that which results from mutual magnetic coupling betwesn inductors L7 and L8 and Lg. ~ndesired EMF~s which are coupled capaciti~ely to the transmission line 16' are balanced out at points ''y" and "z", via mutual capacitances, and only the current I3 will produce a signal, that signal having voltases of opposite phase at points "y" and "z" at the VHF input tc the receiver.
The coaxial llne can be connected directly to r?-ceivers having a low impedance input. Coils in the above-described matrices can ~e wound eith.er as air core or on ma-terials which enhance the permeability of the field around the coil and conse~uently r~duce the size and number of turns.
The air core coil is preferred for the UHF band of channels.
~ he capacitor "C", and inductors Llo, Lll and Ll~
in Figure 2 comprise a high-pass balun air core coupler, for matching the coaxial line transmission iine 16' to the 300 ohm U~F input. It, ~er se, is not considered part of th present invention.
- The presently preferred turns ratio for the VHF
coupler ls 6-1/2:3, and for the UHF coupler 5:3.
Referring now to Figures 3 to 5, an antenna means or receptor 12 ~or use in the present antenna system 10 will be described in detail.
The illustrated antenna means 12 comprises segments of conductors of copper or other suitable material of small cross~sectional area, disposed on a dielectric circuit board or substrate 42 o laminated glass-epoxy or other electrically and mechanically satisfactory composition. The segments may ; be placed on the board 42 using conventional printed circuit techniques. As an alternative, the segments 44, a6 may be formed from small-diameter wire, glued or otherwise secured to the board 42. Other suitable conductors may occur to those sXilled in the art.
It has been found that the performance of the re-ceptor 12 is enha~ced by having the size of the con~uctors 44/ 46 as small as possible. Thus, in the ca~e of an etched conductor in one present embodiment of the invention, a con-ductor having a width of about .015 to .020 inches and a thick-nes~ of two mlls, for a cross-sect onal area of abou~ 3.0 3~56 to 4.0 x 10 5 square inches, is highly sa~isIac~ory. In the case of wire, No. 36 gauge (approximately .005 diameter) has been found satisfactory. Manufacturing considerations and the need for durability dic~ate the practical lower limit for size of the conductors.
The conductors as laid out on ~he,board 42 have a sinuous shape, which may be visualized as being formed by the series connnection of a plurality of mdividual folded monopole elements ~aving pairs of closely spaced conductors 44 and 46. In the illustrated embodiment, the elements a4 and 46 extend outwardly from or inwardly toward th~ center of the board 42, parallel to 2 line radiating from the center "c", and, hence, may be said to extend generally ~adially.
In t~e illustrated embodiment the conductors 44 and 46 de-fining the "pair" are interconnected ~n series at ~heir re-spective outer ends, and thus form an elongated generally U-shaped element, opening inwardly toward the center of the board 42. The conductors 44 and 46 and the respective con-ductors of the other pairs are closely coupled physically, in one pres~ltly useful embodLment being spaced by about .010 inches, and in a~ operative sense are sufficiently closel~
coupled to be subjected sImultaneously to substan~`al7y the same electric gradient of the signal, but delayed in phase as determined by the orientation of the assembly with respec~
to the wave front of an electromagnetic wave. The pairs of conductors in the illustrated embodLment are su~stantially unifor~nly distributed around the board 42.
It is believed that the current produced by the electric gradient flows around the monopolar loop with the ~3~5/6 phase relation determined by the direction ~he wave front is moving, the angle of incidence and the spacing between the conductors, with resul ant resonant impedance variation in the conductors as a function of the frequency of the in-tercepted electsic field. Thus, the segments are believed to provide, in effect, an almost infinite ~umber of resonant elements responsive to a wide range of fxequencies. ~his can be demonstrated by nodal plots of RF "hot spots" on the face of the antenna. Signals which are induced in the looped conductors of receptor 12 automatically produce a pattern of high and low impedance reflection points on the conductors due to the ~ery close spacing of the conductors in the folded segments and ~heir series aiding interconnection. The multi-phased currents in the pairs of conductors 44, 46 appear to minimize magnetic effects, and the observed result is a broad-ly tuned electrostatic effect with a passband of the desired 50 to a~out ~00 MHz. The respective pairs of conductors are cophased connected around the inner periphery of the array, thus enhancing the usea~le electrostatic field without re-radiating any significant part of the energy intercepted.
The evident ericiency of the receptor 12 is be-lieved to be a result of the low ls~el of reradiation as com-pared to that characteristic of the basic dipole family o~
antennas, even as aided by the use of parasitic elements.
As indicz~ed a~ove, the apparent elec~romagnetic reception aperture of the present sm211 receptor is ccmparable to that of a short electric dipole whose aperture is 0.4dB less ef-fecti~e ~han that of a resonant 1/2 ~ dipole, with a con-sequent ~mpro~ement in bandwidth.
~ Y5 6 Comparative tests of ~he present ~ntenna system 10 with conventional "rabbit ear" dipoles demonstrate suffi-cient a~sence of directionaLity to obviate any need for re-adjustment or repositioning of the receptor 12 for each channel.
Indeed, the present antenna system 10 has been shown in some test en~ironments to be as effective as a standard folded dip~le which includes a reflector and a director type outdoor antenna ~hen mounted in a comparable location.
Tests have also shown the present ar.tenna system 10 has no predominant polarity characteristic, i.e. vertical or horizontal, although it has been observed that with the receptor 12 in the vertical plane, rotation will demonstrate a dipole bidirectional characteristic when ~he op~n end of the array is pointed toward ~he zenith. Also, with ~he re-ceptor 12 disposed horizontally, some narrow angle direction-al effects can be o~served in weak signal areas, most notice-a~ly as a phase displacement of the basic color components of television signals. These effects can be reduced by iso-lating the antenna system 10, a minimum of l/2 lambda at the lowest useable frequency t i. e. 50 MHz, from any sizeable metal-lic surface or any self-resonant pipes, guy-wires or similar conduction elements. The present antenna system lO may be used for re~eption of circuLarly polarized energy, and is responsive to ~oth UR~ and VHP signals. Thus, the present antenna system 10 i~ compatible with current and foresee2ble modes of broadcasting, and complies with certain presently proposed Federal Communlcations CQmmiss on Regulations re-quirlng that all TV receivers contain equally efSeGtive UE~
and VHF antennas.
3~
~ or t~iose antenna applications in which some direc-tionality is desired, as for example, where it is desired that reflections or "ghosts" be eliminated, the princlples of the present invention may be applied to elevated rotating support systems. The omni-directional characteristic pro~ides adequate signal, while permitting the principle null response to be directed toward the source of the delayed signal.
Referrins now to Figure 3, the antenna means or receptor 12 is made up of two segments 42, 43 subtending sub-stantially semi-circular sector~, and made up of ~enty-four pairs cf conductor~ 44, 46, substantially uniformly distri~-uted in the sectorsO The segments 42 and 43 are series con-nected and tapped at their electrical center 72, ~ut open circuited at their ends 74 and 76, the ends 74 and 76 being located 180 f:rom the electrical center 72 and coupled to each other only capacitively.
It is along the axis "X-~" defined by the tap point ~the electrical center 72) and the ends 74 and 76 ~hat the directional charactexistic is apparent, there ~eing a sharp null behind the tap point and one or more broad nodes else-where, the princ~pal lobe being directed along the radius on which the open ends 74 and 76 lie. ~hus, when it is in a field free of multi-resonant ob~ects such as metallic pipes or similar conductinq surfaces, the antenna means 12 produces a dPPp null airectional pattern by ~hich the effect of spe-ci~ic undesired signals ma~ be eliminated.
The above-desc~i~ed se~ents 42 and 43 can ~e con-f~`gured with any practical number of elements, ~he greatPr t~e number of elements the smaller ~he dimensi~ns of the an-3r~56 tenna for a gi~en length of conductor. A typical configura-tion uses a total of forty-eight elem2nts disposed in two segments. This makes posslble an efficient antenna only 5"
by 6" and 3/16" thick and ha~ing a conductor approximately twenty-four feet long. Use of twelve radial elements pro-duces ~n excellent FM antenna starting at 80 l~HZ and operat-ing e~ficiently up through the high VHF range. Other con-figurations are feasible.
Altnough the configuration of the antenna means 12 is shown to be radial, there is no particular ad~antage to having either the central terminus of the segments or the outer periphery of the segments follow either ? circular, square or other geometrical shape, as long as the symmetry about the electrical center or tap point 72 is maintained, within 4. In some applica~ions, a square periphery (as shown) might be advantageous, in others an ellipse, or circle could suffice, depending upon the application or manufactur-- ing considerations.
The signal energy captured by the antenna means 12, may be coupled by suitably designed or s~lected signal transmission means, such as the above-described coupling trans-formers 22, 22', 24 and 24', to the input of a signal conver-sion device such as a television set.
It has been found in the antenna systems 10, 10' that undesirable stray coupling effects and the VSWR of the transmission me~ns 14, 14' can be minimized by connecting the tr~nsmission means 14 to the center of the antenna means 12. Thus, for example, in the embodiment shown in Figure .:
~ 3~ ~ ~
3, the inductors L' and L' are mounted on ~he board 42 at the center sf the array of conductors, and the shield 28 of the transmission line 16' is anchored to the board 42 in elec-trical contact with inductor L2 The antenna means 12 may in final assembly be pro-tected from moisture and impact by sealing with a cover mem-ber or plate 78. Receptors can also be equipped with a collar, not shown, to adapt them for outdoor mounting on a standard tubular antenna support mast. If used indoors, antenna means 12 can be supplied with leads 80, seen in Figure 5, laid in the Figure flat against their surfaces and allowins them to ~e placed inside picture frames or hidden behind drapes in locations which provide optimum reception of the available signal. In such an assembly, at least the receptor-to-trans-mission line coupling transformer 22 may be supplied in the sealed unit containing the receptor 12.
The present invention may be embodied in other speci--~ic forms without departing from its spirit or essential at-tributes, and accordingl~, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the inven~ion.
So, too, in the matter of directionality, which, according to the disclosure of that patent is to be controlled by the disposition of the undulations or by the size of the undula-tions, the surprisingly non-directional characteristics at-taina~le with the applicant's system are not suggested.
The present invention has, therefore, as its prin-cipal o~ject, the provision of a compact high efriciency broad-ba~d antenna system, the characteristics of ~ich are substan-tially omni-directional, but which, as will be shown, has a sharp null zone, which may ~e used to reduce undesired in-terference levels.
The foregoing and other objects are realized, in a presently p~eferred for~ of ~he in~ention, by a sys'em wh_ch employs a novel complement of a multi-resonant su~stantially non-reradiating receptor and output matching load coupler and a low VSWR transmission line and signal conversion load coupler.
In a presently ~referred form of the invention, 3`{~7~6 the receptor has a plurality of individual segments disposed in a s~etrical array, the sesments being wire-like conduc-tive members, sinuous ln configuration. The sesments may ~e conceptualized as consisting of a series of multi-resonant folded monopolar elements connected in series~ The conductors defining the segments and their elements are of small cross-sectional dimension, i~ having been found that, in general, the smaller the cross-section of the conductors and the more closely they are spaced the more satisfactory the performance of the antenna. Although, consistent with the principles of the invention, the conductors may be wire, or preferably, created by printed circuit techniques, they are sometimes referred herein as "wire-like" to signify their small cross-sectional area, and their tight-folded loop configuration so as to distinguish them rrom large self-supporting antenna-forming elements such as tubing or castings.
The electrically symmetrical receptor apparently presents to the sending end of the transmission line vi~ the coupler system a broad-~and frequency response and impedance comparable to that of ~ree space, i.e., 120 pi. The sending end of the transm~ssion line in the presently preferred em-bodLment consists of a series loading coil which is connected to the receptor at the electrical center point of the receptor, and îs both elac~r~cally and inductively coupled to the low Lmpedance low VSWR transmission line.
SLnce the present receptor is electrically symmet--rical with respect to its feed point, it is relatively insen-sitive to the magnetic component of the eiectromasnetic field.
Under these conditions a very ~mall RF surface current lows ~3~ 6 on the receptor, and consequently does not result in a signi-ficant reradiation of the field received. Any curr~nts which result from the a~sorption of ~he electric field will appear at the common junction point of the two halves of the receptor, in phase relationships which vary with frequency, due to the multi-resonant modes of the interconnec~ing monopoles, there-by reducing the magnitude of the current flow in ~he receptor elements and raising its radiation resistance to a point where, it is believed, the receptor becomes essentially a bridging source of energy between the transmission line coupling system and free space.
For the purpose of illustrating the invention, there are shown in the drawings forms of the invention which ~re presently preferred, it being understood, however, that this invention is not limited to the precise arrang~ments and in-str~entalittes shown.
Figure 1 is a circuit schematic drawing of an anten-na system in accordance with the invent~`on, in an embodiment using a conventional 300 ohm twin lezd transmission line.
Figure 2 is a circuit schematic drawing showing a modified form of antenna system in accordance with the in-vention, in an ~mbodiment using a conventional low impedance coaxial transmission line.
Figure 3 is a plan ~ie~, in approximately full scale, illustr ting an embodim~nt of ar antenna means or receptor ~or use in an antenna system in accordanc~ wi~h ~Ihe present invention.
Figure 4 is a side elevatio~ Yiew of the embodiment of Figure 3, depicting somewhat diagrammat-cally ~not to scale) ~3~5~
t~e relationship between the segments and the substrate on which they are supported.
Figure 5 is a pictorial view of an zntenna means or receptor in accordance with the inven~ionO
Figure ~ is a pic~orial view of a core upon which the antenna load inductors and transmission line couplers may ~e wound in accordance with the invention.
~3~3S6 D ~
Reerring now to the drawinss in de~ail, wherein like numerals indicate like elements, there is seen in Figure 1 an antenna system designated generally by the reference numeral 10..
The antenna system 10 comprises antenna means, d~sig-n~ted yenerally by ~he reference numeral 12, in the form of a multi-resonant, subst~ntially non-radiating electrically symmetrical receptor (which will ~e described in greater de-tail below); and signal transmission means, designated gen-erally by the reference numeral 14y for coupling the antenna means 12 to a load.
The transmission means 14 in the form of the in~en tion illustrated in Figure 1 comprises a balanced transmission line 16 of the parallel conductor (300 ohm~ type, and having conductors 18 and 20; a coupling transformer designated gen-eraLly by the reference numeral 22 connected to the antenna means 12 and the transmission line 14; and another coupling transformer, designated generally by the refe~ence numeral 24 connected to the transmlssion line 16 and an input terminal of a load or dri~en de~ice ~designated by the symbol "L")~
The coupling transformer 22 has a prima~y winding in the form or an inductor Ll, which is connected to ~he an-tenna means 12 as a loading coil at the electrical center ~Ic~ of the antenna means 12. In one presently contemplatad form of the in~ention, the inductor Ll can be made integral with the antenna means 12, as will De explained ~elow.
3~6 The secondary winding of ~he coupling transformer 22 comprises a pair of like-wound series-connected coils or inductors L2 and L3, having e~ual numbers of t~lrns, each ln-ductively coupled to the inductor Ll. The mductor Ll is also electrically connected ~o the secondary winding, its ~inish being connected to the junction "d" of L2 and L3, that junction being, in ~iew of the values of L2 and L3, the elec-trical center of the secondary winding. In one present form of the coupling transformer 2~, the number of turns in the inductor Ll is in the ratio of 2:1 with the number of turns in each of the inductors L2 and L3.
The conductQrs 18 and 20 of the t~ansmission line 16 are connected, respecti~ely, at their antenna ends to ~he start 7'e" and finish "f" of the secondary windings. The oth~r ends of the conductors 18 and 20 are connected, respectively, at junctions "g" and "h'l to the primary windings of the couplins transformer 24.
The primary windings of the coupling transformer 24 comprise li.ke-wound sexies-connected coils or inductors L4 and L5, having equal numbers of turns, and the secondary windings comprise an inductor L6. In one present form of the coupling transformer 24, the num~er of turns ln each of the inductors L4 and L5 is i~ the ratio of 2:1 with ~he number of turns in ~he inductor L6. A conductor 26 connects the electrical center "i" of the pr~mary windings L4, L5 and ~e finish of inductor L6.
The manner of oper~tion o ~he antenna system 10 should ncw ~e apparent.
The electrcmagnetic field is in~ercepted by ~e .
antenna means 12, causing a cuxrent to flow, the current and voltage being in phase at point "c" and the voltage a maximum at points "a" a~d "b". The in-phase voltage and current of point "c" (the electrical center of the antenna means 12) produces a resultant current Il ~hrough inductor Ll. The current Il is equally divided at junction "d", half goins through L2 and conductor 2~ and half through inductor L3 and conductor 18, and remains divided until it reaches the junc-tion "i" of inductors L4 and L5. The preceding conditions obtain, when the antenna is optimall~ directed toward the transmitting station.
It will be recognized that current Il, meets only one ~ignificant impedance, namely, Ll, since the equal com-ponents of Il, in L2 and L3 produce equal voltages of the same phase at junctions "e" and "f". The point "i", at which the halves of current Il, rejoin, is the electrical center of the primary winding of coupling transformer 24, and is at g~ound po1:ential, the conductor 26 being connected to the grounded input termlnal of the load through point ";". As a result of mutual inductance, the halves of Il produce equal voltages of opposite phase at points "g" and "h", so no com-ponent of current Il is induced in inductor L6. In signal conversion de~ices ha~ing an unbalanced input, i.e. either input terminal grounded, the finish end of L6 point "j" would be connected to th~ grounded terminal.
Current Il do~g generate, howe~er, by mutual induc-tion, a current I2 which flows in the circuit consisting of inductors L2 and L3, transmission line 16 ~conductors 18 and 5~
20~, and inductors L4 and L5. The current I2 induces by coupling between inductors L4 and L5 a current I3 in inductor L6, thus producing a ~oltage "v" across the input of the receiver input load.
The advantage of this syst~m is that perfect symmet~y occurs from point "c" to point "i", resulting in a minimum reactive transmission line with a minimum VSWR and broad b~r.d resistive termination.
In the presently contemplated best mcde of carryir.g out the present invention, the inductors Ll, L2 and L3 are wound from equal lengths of very fine wire, twisted together to interwind them with approximately 15 twists per inch and tightly wound into a very small coil with the start of L2 and the fini~h of L3 forming the above-mentioned junction at "d". The finish of Ll is al50 terminated at "di'.
Th~! impedance of Ll can be raised 2S desired by adding a fourth wire, not shown in the drawing, twisted to-geth~r with the three other wires to form a series aiding coil. When Ll is made up of two wires, the finish of one wire is connected to the start of the second wire and the finish of the second wire is connected to junction "d". When the antenna means 12 has relatively chort conductor lengths, the enhanced inductance of the thus-modified inductor Ll pro-duces ~he higher imped nce matching coupling required for a smaller electric dipole.
Winding of the inductors Ll, L2 and L3 Gn a suit-able high permeabllity core, such as is illustrated in Figure 6, can reduce the capacitance between turns by reducing the amount of wire needed to zttain the desired inductance. This 3~56 results in a better Lmpeda~ce match at VHF and a more uniform response in the UHF range. In the presently prefe~red form of the invention, the inductors are simultaneously quadrifllar, trifilar or bifilar wound on the twin hole balun core desig-nated in Figure 6 by the rererence numeral 23, there being approximately one and one-half (l-l/2) turns in each of the coils, and the transformer having an impedance transformation ratio of 2:1. The core for the coupling transformer 22 in the presently pxeferred form includes a pair of spaced parallel bores 25 and 27 for receiving the wires forming inductors L2 and L3, and the wires forming inductors Ll, L2 and L3 are wound around the core 23. Winding in this manner ensures the desired ~ery tight coupling with minimum leakage reactance between inductors such as L2 and L3 and L4 and L5.
The core material presently preferred is a ferroxide made and sold by ~rystinel Corp., of Port Chester, New York, and designated "~-405" with a nominal permeability (mu) of 370. In an operatlve embodiment, ~he core is .001 i~. hlgh, ~141 in. wide and .079 in~ long, and the bores 25 and 27 re .031 in. in diameter. The important properties of the core material for V~/U~E applications ar~ its permeability and "Q", the product of which will be recognized as a measure of inZuctive efficiency~
Referrlng now to Figure 2, there i5 seen a mod fied form of antenna system wherein elements corresponding to those previ~usly described are designated b~ like, pri,~ed reference numerals.
The embodiment of the invention depicted in Figure 2 utilizes an unbalanced coaxial tr~nsmission line 16' (con-~ ~3;~5~
ventionally of 75 ohms though other impedances may be used).
Such transmission lines offer some advantages when used with recPivers having poor signai balance at their input terminals, or which radiate spurlous oscillations which disturb the in-cident sig~al on an open line.
The finish of inductor Ll is connected to the start of inductor L~ at point "d"'. The shield 28 of the transmission line 16' is connected to the finish of inductor L~ at point "e "', and the center wire 20 of the transmission line 16' to point "d"'. Current I2 induced in inducto L2, passes through inductor L7 to the transmlssion line shield 28.
Current I~ travels directly through inductors Li and L2 to the shield 28 at point "e "' and subsequently to point "k", the common terminal of inductors L7 and Llo, which are inductively coupled~ respectively, to windings L8, Lg, Lll and L12 of the coupling transformers 24' and 24", the wlndings comprising liXe-wound inductors of equal value. No current will be induced in inductor L8 and inductor L9 ex-cept that which results from mutual magnetic coupling betwesn inductors L7 and L8 and Lg. ~ndesired EMF~s which are coupled capaciti~ely to the transmission line 16' are balanced out at points ''y" and "z", via mutual capacitances, and only the current I3 will produce a signal, that signal having voltases of opposite phase at points "y" and "z" at the VHF input tc the receiver.
The coaxial llne can be connected directly to r?-ceivers having a low impedance input. Coils in the above-described matrices can ~e wound eith.er as air core or on ma-terials which enhance the permeability of the field around the coil and conse~uently r~duce the size and number of turns.
The air core coil is preferred for the UHF band of channels.
~ he capacitor "C", and inductors Llo, Lll and Ll~
in Figure 2 comprise a high-pass balun air core coupler, for matching the coaxial line transmission iine 16' to the 300 ohm U~F input. It, ~er se, is not considered part of th present invention.
- The presently preferred turns ratio for the VHF
coupler ls 6-1/2:3, and for the UHF coupler 5:3.
Referring now to Figures 3 to 5, an antenna means or receptor 12 ~or use in the present antenna system 10 will be described in detail.
The illustrated antenna means 12 comprises segments of conductors of copper or other suitable material of small cross~sectional area, disposed on a dielectric circuit board or substrate 42 o laminated glass-epoxy or other electrically and mechanically satisfactory composition. The segments may ; be placed on the board 42 using conventional printed circuit techniques. As an alternative, the segments 44, a6 may be formed from small-diameter wire, glued or otherwise secured to the board 42. Other suitable conductors may occur to those sXilled in the art.
It has been found that the performance of the re-ceptor 12 is enha~ced by having the size of the con~uctors 44/ 46 as small as possible. Thus, in the ca~e of an etched conductor in one present embodiment of the invention, a con-ductor having a width of about .015 to .020 inches and a thick-nes~ of two mlls, for a cross-sect onal area of abou~ 3.0 3~56 to 4.0 x 10 5 square inches, is highly sa~isIac~ory. In the case of wire, No. 36 gauge (approximately .005 diameter) has been found satisfactory. Manufacturing considerations and the need for durability dic~ate the practical lower limit for size of the conductors.
The conductors as laid out on ~he,board 42 have a sinuous shape, which may be visualized as being formed by the series connnection of a plurality of mdividual folded monopole elements ~aving pairs of closely spaced conductors 44 and 46. In the illustrated embodiment, the elements a4 and 46 extend outwardly from or inwardly toward th~ center of the board 42, parallel to 2 line radiating from the center "c", and, hence, may be said to extend generally ~adially.
In t~e illustrated embodiment the conductors 44 and 46 de-fining the "pair" are interconnected ~n series at ~heir re-spective outer ends, and thus form an elongated generally U-shaped element, opening inwardly toward the center of the board 42. The conductors 44 and 46 and the respective con-ductors of the other pairs are closely coupled physically, in one pres~ltly useful embodLment being spaced by about .010 inches, and in a~ operative sense are sufficiently closel~
coupled to be subjected sImultaneously to substan~`al7y the same electric gradient of the signal, but delayed in phase as determined by the orientation of the assembly with respec~
to the wave front of an electromagnetic wave. The pairs of conductors in the illustrated embodLment are su~stantially unifor~nly distributed around the board 42.
It is believed that the current produced by the electric gradient flows around the monopolar loop with the ~3~5/6 phase relation determined by the direction ~he wave front is moving, the angle of incidence and the spacing between the conductors, with resul ant resonant impedance variation in the conductors as a function of the frequency of the in-tercepted electsic field. Thus, the segments are believed to provide, in effect, an almost infinite ~umber of resonant elements responsive to a wide range of fxequencies. ~his can be demonstrated by nodal plots of RF "hot spots" on the face of the antenna. Signals which are induced in the looped conductors of receptor 12 automatically produce a pattern of high and low impedance reflection points on the conductors due to the ~ery close spacing of the conductors in the folded segments and ~heir series aiding interconnection. The multi-phased currents in the pairs of conductors 44, 46 appear to minimize magnetic effects, and the observed result is a broad-ly tuned electrostatic effect with a passband of the desired 50 to a~out ~00 MHz. The respective pairs of conductors are cophased connected around the inner periphery of the array, thus enhancing the usea~le electrostatic field without re-radiating any significant part of the energy intercepted.
The evident ericiency of the receptor 12 is be-lieved to be a result of the low ls~el of reradiation as com-pared to that characteristic of the basic dipole family o~
antennas, even as aided by the use of parasitic elements.
As indicz~ed a~ove, the apparent elec~romagnetic reception aperture of the present sm211 receptor is ccmparable to that of a short electric dipole whose aperture is 0.4dB less ef-fecti~e ~han that of a resonant 1/2 ~ dipole, with a con-sequent ~mpro~ement in bandwidth.
~ Y5 6 Comparative tests of ~he present ~ntenna system 10 with conventional "rabbit ear" dipoles demonstrate suffi-cient a~sence of directionaLity to obviate any need for re-adjustment or repositioning of the receptor 12 for each channel.
Indeed, the present antenna system 10 has been shown in some test en~ironments to be as effective as a standard folded dip~le which includes a reflector and a director type outdoor antenna ~hen mounted in a comparable location.
Tests have also shown the present ar.tenna system 10 has no predominant polarity characteristic, i.e. vertical or horizontal, although it has been observed that with the receptor 12 in the vertical plane, rotation will demonstrate a dipole bidirectional characteristic when ~he op~n end of the array is pointed toward ~he zenith. Also, with ~he re-ceptor 12 disposed horizontally, some narrow angle direction-al effects can be o~served in weak signal areas, most notice-a~ly as a phase displacement of the basic color components of television signals. These effects can be reduced by iso-lating the antenna system 10, a minimum of l/2 lambda at the lowest useable frequency t i. e. 50 MHz, from any sizeable metal-lic surface or any self-resonant pipes, guy-wires or similar conduction elements. The present antenna system lO may be used for re~eption of circuLarly polarized energy, and is responsive to ~oth UR~ and VHP signals. Thus, the present antenna system 10 i~ compatible with current and foresee2ble modes of broadcasting, and complies with certain presently proposed Federal Communlcations CQmmiss on Regulations re-quirlng that all TV receivers contain equally efSeGtive UE~
and VHF antennas.
3~
~ or t~iose antenna applications in which some direc-tionality is desired, as for example, where it is desired that reflections or "ghosts" be eliminated, the princlples of the present invention may be applied to elevated rotating support systems. The omni-directional characteristic pro~ides adequate signal, while permitting the principle null response to be directed toward the source of the delayed signal.
Referrins now to Figure 3, the antenna means or receptor 12 is made up of two segments 42, 43 subtending sub-stantially semi-circular sector~, and made up of ~enty-four pairs cf conductor~ 44, 46, substantially uniformly distri~-uted in the sectorsO The segments 42 and 43 are series con-nected and tapped at their electrical center 72, ~ut open circuited at their ends 74 and 76, the ends 74 and 76 being located 180 f:rom the electrical center 72 and coupled to each other only capacitively.
It is along the axis "X-~" defined by the tap point ~the electrical center 72) and the ends 74 and 76 ~hat the directional charactexistic is apparent, there ~eing a sharp null behind the tap point and one or more broad nodes else-where, the princ~pal lobe being directed along the radius on which the open ends 74 and 76 lie. ~hus, when it is in a field free of multi-resonant ob~ects such as metallic pipes or similar conductinq surfaces, the antenna means 12 produces a dPPp null airectional pattern by ~hich the effect of spe-ci~ic undesired signals ma~ be eliminated.
The above-desc~i~ed se~ents 42 and 43 can ~e con-f~`gured with any practical number of elements, ~he greatPr t~e number of elements the smaller ~he dimensi~ns of the an-3r~56 tenna for a gi~en length of conductor. A typical configura-tion uses a total of forty-eight elem2nts disposed in two segments. This makes posslble an efficient antenna only 5"
by 6" and 3/16" thick and ha~ing a conductor approximately twenty-four feet long. Use of twelve radial elements pro-duces ~n excellent FM antenna starting at 80 l~HZ and operat-ing e~ficiently up through the high VHF range. Other con-figurations are feasible.
Altnough the configuration of the antenna means 12 is shown to be radial, there is no particular ad~antage to having either the central terminus of the segments or the outer periphery of the segments follow either ? circular, square or other geometrical shape, as long as the symmetry about the electrical center or tap point 72 is maintained, within 4. In some applica~ions, a square periphery (as shown) might be advantageous, in others an ellipse, or circle could suffice, depending upon the application or manufactur-- ing considerations.
The signal energy captured by the antenna means 12, may be coupled by suitably designed or s~lected signal transmission means, such as the above-described coupling trans-formers 22, 22', 24 and 24', to the input of a signal conver-sion device such as a television set.
It has been found in the antenna systems 10, 10' that undesirable stray coupling effects and the VSWR of the transmission me~ns 14, 14' can be minimized by connecting the tr~nsmission means 14 to the center of the antenna means 12. Thus, for example, in the embodiment shown in Figure .:
~ 3~ ~ ~
3, the inductors L' and L' are mounted on ~he board 42 at the center sf the array of conductors, and the shield 28 of the transmission line 16' is anchored to the board 42 in elec-trical contact with inductor L2 The antenna means 12 may in final assembly be pro-tected from moisture and impact by sealing with a cover mem-ber or plate 78. Receptors can also be equipped with a collar, not shown, to adapt them for outdoor mounting on a standard tubular antenna support mast. If used indoors, antenna means 12 can be supplied with leads 80, seen in Figure 5, laid in the Figure flat against their surfaces and allowins them to ~e placed inside picture frames or hidden behind drapes in locations which provide optimum reception of the available signal. In such an assembly, at least the receptor-to-trans-mission line coupling transformer 22 may be supplied in the sealed unit containing the receptor 12.
The present invention may be embodied in other speci--~ic forms without departing from its spirit or essential at-tributes, and accordingl~, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the inven~ion.
Claims
I claim:
1. A broad-band receiving antenna system compris-ing antenna means and transmission means for coupling said antenna means to a signal conversion device, said antenna means comprising a multi-resonant substantially non-radiating electrically responsive symmetrical electric dipole receptor responsive to signals in the VHF and UHF broadcast bands, and said transmission means comprising a transmission line, a first coupling transformer connected to said antenna means and said transmission line, and a second coupling transformer connected to said transmission line and adapted to be con-nected to a signal conversion device.
2. Apparatus in accordance with claim 1, wherein the primary winding of said first coupling transformer is connected to said antenna means as a loading coil at the elec-trical center of said antenna means, and said transmission line and said first and second coupling transformers are so connected that current in said primary winding produces sig-nals at the output of said second coupling transformer only by inductive coupling between respective secondary and pri-mary windings of said first and second coupling transformers.
3. Apparatus in accordance with claim 2, wherein the secondary winding of said first coupling transformer com-prises inductor means inductively coupled to said primary winding, and the finish of said primary winding is connected to said secondary winding at the center tap of said secondary winding.
4. Apparatus in accordance with claim 3, wherein said primary and secondary windings of said first coupling transformer are quadrifilar wound.
5. Apparatus in accordance with claim 3, wherein said primary winding and said coils of said secondary winding of said first coupling transformer are guadrifilar wound from conductors of equal length.
5. Apparatus in accordance with claim 5, wherein said primary winding and said coils are wound on a core having a pair of spaced bores therein, and said coils comprising conductors received in said bores.
7. Apparatus in accordance with claim 1, wherein the primary winding of said first coupling transformer is connected to said antenna means at the electrical center of said antenna means and the secondary winding of said first coupling transformer comprises a pair of series-connected coils, the finish end of said primary winding being connected to the center tap of said coils, and said transmission line being of the parallel type and comprising a pair of like con-ductors, one of said conductors being connected to the start and the other of said conductors being connected to the finish of said secondary winding, and said second coupling transformer comprising a primary winding, said conductors being connected, respectively to the start and finish of said primary winding, a secondary winding inductively coupled to said primary wind-ing and providing an input for the load, and a conductor be-tween a center tap or said primary winding of said second coupling transformer and the finish of said secondary wind-ing of said second coupling transformer.
8. Apparatus in accordance with claim 5, wherein said primary and secondary windings of said second coupling transformer are quadrifilar wound.
9. Apparatus in accordance with claim 1, wherein the primary winding of said first coupling transformer is connected to said antenna means as a loading coil at the elec-trical center of said antenna means and the secondary wind-ing of said first coupling transformer comprises a second coil, the finish end of said primary winding being connected to the start of said second coil, said transmission line being of the coaxial type having a center conductor and conductive shield, said second coupling transformer comprising a pri-mary winding connected between said center conductor and said shield and a secondary winding inductively coupled to said primary winding, said center conductor being connected to the junction between said primary and said secondary wind-ings of said first coupling transformer, and said shield being connected to the finish of said secondary winding of said first coupling transformer.
10. Apparatus in accordance with claim 9, wherein said secondary winding of said second coupling transformer comprises inductor means inductively coupled to said primary winding.
11. Apparatus in accordance with claim 9, wherein said coupling transformers are autotransformers.
12. Apparatus in accordance with claim 10, wherein said primary and secondary windings of said second coupling transformer are quadrifilar, trifilar or bifilar wound.
13. A broad-band receiving antenna system comprising antenna means and transmission means for coupling said antenna means to a load, said antenna means comprising a multi-resonant substantially non-radiating electrically responsive symmetrical electric dipole receptor responsive to signals in the VHF
and UHF broadcast bands, and said transmission means comprising a transmission line and a coupling transformer connected to said antenna means and said transmission line, said coupling transformer having its primary winding connected to said an-tenna means as a loading coil at the electrical center of said antenna means, the secondary winding of said coupling transformer comprising a series-connected coil inductively coupled to said primary winding, and the finish of said pri-mary winding being connected to the start of said secondary winding.
14. For use in an antenna system comprising antenna means and transmission means for coupling the antenna means to a load, a coupling transformer comprising a primary winding adapted to be connected to antenna means as a loading coil, and a secondary winding inductively coupled to said primary winding and adapted to be connected to a transmission line, said secondary winding comprising llke-wound coils connected in series, the finish of said primary winding being connected to the junction of said coils of said secondary winding.
15. Apparatus in accordance with claim 14, wherein said primary winding and said coils are interwound.
16. Apparatus in accordance with claim 15, wherein said primary winding and said coils are interwound from con-ductors of equal length.
17. Apparatus in accordance with claim 16, wherein said primary winding and said coils are wound on a ferroxide core having a pair of openings therein.
1. A broad-band receiving antenna system compris-ing antenna means and transmission means for coupling said antenna means to a signal conversion device, said antenna means comprising a multi-resonant substantially non-radiating electrically responsive symmetrical electric dipole receptor responsive to signals in the VHF and UHF broadcast bands, and said transmission means comprising a transmission line, a first coupling transformer connected to said antenna means and said transmission line, and a second coupling transformer connected to said transmission line and adapted to be con-nected to a signal conversion device.
2. Apparatus in accordance with claim 1, wherein the primary winding of said first coupling transformer is connected to said antenna means as a loading coil at the elec-trical center of said antenna means, and said transmission line and said first and second coupling transformers are so connected that current in said primary winding produces sig-nals at the output of said second coupling transformer only by inductive coupling between respective secondary and pri-mary windings of said first and second coupling transformers.
3. Apparatus in accordance with claim 2, wherein the secondary winding of said first coupling transformer com-prises inductor means inductively coupled to said primary winding, and the finish of said primary winding is connected to said secondary winding at the center tap of said secondary winding.
4. Apparatus in accordance with claim 3, wherein said primary and secondary windings of said first coupling transformer are quadrifilar wound.
5. Apparatus in accordance with claim 3, wherein said primary winding and said coils of said secondary winding of said first coupling transformer are guadrifilar wound from conductors of equal length.
5. Apparatus in accordance with claim 5, wherein said primary winding and said coils are wound on a core having a pair of spaced bores therein, and said coils comprising conductors received in said bores.
7. Apparatus in accordance with claim 1, wherein the primary winding of said first coupling transformer is connected to said antenna means at the electrical center of said antenna means and the secondary winding of said first coupling transformer comprises a pair of series-connected coils, the finish end of said primary winding being connected to the center tap of said coils, and said transmission line being of the parallel type and comprising a pair of like con-ductors, one of said conductors being connected to the start and the other of said conductors being connected to the finish of said secondary winding, and said second coupling transformer comprising a primary winding, said conductors being connected, respectively to the start and finish of said primary winding, a secondary winding inductively coupled to said primary wind-ing and providing an input for the load, and a conductor be-tween a center tap or said primary winding of said second coupling transformer and the finish of said secondary wind-ing of said second coupling transformer.
8. Apparatus in accordance with claim 5, wherein said primary and secondary windings of said second coupling transformer are quadrifilar wound.
9. Apparatus in accordance with claim 1, wherein the primary winding of said first coupling transformer is connected to said antenna means as a loading coil at the elec-trical center of said antenna means and the secondary wind-ing of said first coupling transformer comprises a second coil, the finish end of said primary winding being connected to the start of said second coil, said transmission line being of the coaxial type having a center conductor and conductive shield, said second coupling transformer comprising a pri-mary winding connected between said center conductor and said shield and a secondary winding inductively coupled to said primary winding, said center conductor being connected to the junction between said primary and said secondary wind-ings of said first coupling transformer, and said shield being connected to the finish of said secondary winding of said first coupling transformer.
10. Apparatus in accordance with claim 9, wherein said secondary winding of said second coupling transformer comprises inductor means inductively coupled to said primary winding.
11. Apparatus in accordance with claim 9, wherein said coupling transformers are autotransformers.
12. Apparatus in accordance with claim 10, wherein said primary and secondary windings of said second coupling transformer are quadrifilar, trifilar or bifilar wound.
13. A broad-band receiving antenna system comprising antenna means and transmission means for coupling said antenna means to a load, said antenna means comprising a multi-resonant substantially non-radiating electrically responsive symmetrical electric dipole receptor responsive to signals in the VHF
and UHF broadcast bands, and said transmission means comprising a transmission line and a coupling transformer connected to said antenna means and said transmission line, said coupling transformer having its primary winding connected to said an-tenna means as a loading coil at the electrical center of said antenna means, the secondary winding of said coupling transformer comprising a series-connected coil inductively coupled to said primary winding, and the finish of said pri-mary winding being connected to the start of said secondary winding.
14. For use in an antenna system comprising antenna means and transmission means for coupling the antenna means to a load, a coupling transformer comprising a primary winding adapted to be connected to antenna means as a loading coil, and a secondary winding inductively coupled to said primary winding and adapted to be connected to a transmission line, said secondary winding comprising llke-wound coils connected in series, the finish of said primary winding being connected to the junction of said coils of said secondary winding.
15. Apparatus in accordance with claim 14, wherein said primary winding and said coils are interwound.
16. Apparatus in accordance with claim 15, wherein said primary winding and said coils are interwound from con-ductors of equal length.
17. Apparatus in accordance with claim 16, wherein said primary winding and said coils are wound on a ferroxide core having a pair of openings therein.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US903,056 | 1978-05-05 | ||
| US05/903,056 US4318109A (en) | 1978-05-05 | 1978-05-05 | Planar antenna with tightly wound folded sections |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1143056A true CA1143056A (en) | 1983-03-15 |
Family
ID=25416868
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000327075A Expired CA1143056A (en) | 1978-05-05 | 1979-05-07 | Broad-band antenna systems |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4318109A (en) |
| JP (1) | JPS5547701A (en) |
| CA (1) | CA1143056A (en) |
| DE (1) | DE2918055A1 (en) |
| FR (1) | FR2425161A1 (en) |
| GB (1) | GB2020488A (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2236745T3 (en) * | 1995-08-09 | 2005-07-16 | Fractal Antenna Systems Inc. | ANTENAS RESONADORES AND ELEMENTS OF FRACTAL LOAD. |
| US20060119525A1 (en) * | 2004-08-24 | 2006-06-08 | Nathan Cohen | Wideband antenna system for garments |
| US7019695B2 (en) | 1997-11-07 | 2006-03-28 | Nathan Cohen | Fractal antenna ground counterpoise, ground planes, and loading elements and microstrip patch antennas with fractal structure |
| US6452553B1 (en) * | 1995-08-09 | 2002-09-17 | Fractal Antenna Systems, Inc. | Fractal antennas and fractal resonators |
| US20050231426A1 (en) * | 2004-02-02 | 2005-10-20 | Nathan Cohen | Transparent wideband antenna system |
| US6104349A (en) * | 1995-08-09 | 2000-08-15 | Cohen; Nathan | Tuning fractal antennas and fractal resonators |
| US6445352B1 (en) * | 1997-11-22 | 2002-09-03 | Fractal Antenna Systems, Inc. | Cylindrical conformable antenna on a planar substrate |
| FR2781587B1 (en) * | 1998-07-21 | 2000-09-08 | Dassault Electronique | ADVANCED READER FOR NON-CONTACT BADGES |
| KR100322119B1 (en) | 1998-07-31 | 2002-05-09 | 윤종용 | Planar broadband dipole antenna for linearly polariged waves |
| CN101188325B (en) | 1999-09-20 | 2013-06-05 | 弗拉克托斯股份有限公司 | Multi-level antenna |
| WO2001054225A1 (en) * | 2000-01-19 | 2001-07-26 | Fractus, S.A. | Space-filling miniature antennas |
| ATE364911T1 (en) * | 2001-10-16 | 2007-07-15 | Fractus Sa | LOADED ANTENNA |
| US9755314B2 (en) | 2001-10-16 | 2017-09-05 | Fractus S.A. | Loaded antenna |
| JP2006510321A (en) * | 2002-12-22 | 2006-03-23 | フラクタス・ソシエダッド・アノニマ | Multiband monopole antenna for mobile communication devices |
| EP1709704A2 (en) | 2004-01-30 | 2006-10-11 | Fractus, S.A. | Multi-band monopole antennas for mobile communications devices |
| US8738103B2 (en) | 2006-07-18 | 2014-05-27 | Fractus, S.A. | Multiple-body-configuration multimedia and smartphone multifunction wireless devices |
| RU2564694C1 (en) * | 2014-03-31 | 2015-10-10 | Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Южный федеральный университет" (Южный федеральный университет) | Transceiving oblique polarization antenna array formed by 2·n-pairs of codirectional v-shaped vibrators |
| RU2562145C1 (en) * | 2014-03-31 | 2015-09-10 | Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Южный федеральный университет" (Южный федеральный университет) | Transceiving all-band oblique polarization antenna array formed by 2*n-pairs of monoplane v-shaped vibrators |
| RU2617794C2 (en) * | 2015-08-25 | 2017-04-26 | федеральное государственное автономное образовательное учреждение высшего образования "Южный федеральный университет" (Южный федеральный университет) | Send-receive positioning and long-distance module antenna array of mobile multi-function longtime heart monitoring and ergometry hardware and software complex |
| RU2617796C2 (en) * | 2015-08-25 | 2017-04-26 | федеральное государственное автономное образовательное учреждение высшего образования "Южный федеральный университет" (Южный федеральный университет) | Positioning and long-distance module oblique polarization antenna array of mobile multi-function longtime heart monitoring and ergometry hardware and software complex |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US760463A (en) * | 1904-05-24 | Guglielmo marooni | ||
| US2021734A (en) * | 1932-05-14 | 1935-11-19 | Int Communications Lab Inc | Transmission line network for radio receiving antennae |
| US2039988A (en) * | 1935-09-30 | 1936-05-05 | Jr Walker Coleman Graves | Radio antenna unit |
| US2166750A (en) * | 1936-02-15 | 1939-07-18 | Rca Corp | Antenna |
| US2648001A (en) * | 1946-04-11 | 1953-08-04 | Us Navy | Ring type antenna |
| US2761140A (en) * | 1952-04-23 | 1956-08-28 | George B Ashton | Antenna |
| US2780808A (en) * | 1953-12-15 | 1957-02-05 | Marvin P Middlemark | High frequency antennas |
| US2821710A (en) * | 1954-08-06 | 1958-01-28 | George H Ferriman | Television antenna |
| US2875441A (en) * | 1954-10-14 | 1959-02-24 | James A Mcgrane | Twin multiple loop television antenna |
| US3050730A (en) * | 1959-07-09 | 1962-08-21 | Sylvania Electric Prod | Broadband plate antenna |
| US2990547A (en) * | 1959-07-28 | 1961-06-27 | Boeing Co | Antenna structure |
| GB927051A (en) * | 1959-10-07 | 1963-05-22 | Rudolf Guertler | Improvements in or relating to antennas for high frequencies |
| US3231894A (en) * | 1960-06-23 | 1966-01-25 | Sony Corp | Zigzag antenna |
| US3344425A (en) * | 1966-06-13 | 1967-09-26 | James E Webb | Monopulse tracking system |
| US3465344A (en) * | 1967-01-26 | 1969-09-02 | Sylvania Electric Prod | Single antenna dual frequency band signal coupling system |
| US3454951A (en) * | 1967-05-05 | 1969-07-08 | North American Rockwell | Spiral antenna with zigzag arms to reduce size |
| US3541475A (en) * | 1968-06-12 | 1970-11-17 | Rca Corp | Line terminating circuits |
| US3587105A (en) * | 1968-09-12 | 1971-06-22 | Warren E Neilson | Picture framed antenna |
| US3689929A (en) * | 1970-11-23 | 1972-09-05 | Howard B Moody | Antenna structure |
| US3716861A (en) * | 1971-03-22 | 1973-02-13 | J Root | Serpentine antenna mounted on a rotatable capacitive coupler |
-
1978
- 1978-05-05 US US05/903,056 patent/US4318109A/en not_active Expired - Lifetime
-
1979
- 1979-05-04 DE DE19792918055 patent/DE2918055A1/en not_active Withdrawn
- 1979-05-07 JP JP5484079A patent/JPS5547701A/en active Pending
- 1979-05-07 FR FR7911486A patent/FR2425161A1/en not_active Withdrawn
- 1979-05-07 CA CA000327075A patent/CA1143056A/en not_active Expired
- 1979-05-08 GB GB7915930A patent/GB2020488A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| FR2425161A1 (en) | 1979-11-30 |
| JPS5547701A (en) | 1980-04-04 |
| US4318109A (en) | 1982-03-02 |
| DE2918055A1 (en) | 1979-11-15 |
| GB2020488A (en) | 1979-11-14 |
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