DE4321805A1 - Vehicle FM and TV broadcasting antenna system - combines phase shifted broadcast signals and selects signal for best reception using diversity control - Google Patents

Abstract

The FM antenna system has main and auxiliary antennae (11,12) to receive an FM transmission and output main and auxiliary FM signal respectively. A variable phase shifter combines the output signals with a set phase shift between them. The FM system operates with diversity reception (16) in which it selects a signal from the combined signal which will be received well. The main and the auxiliary signals are combined with a phase difference such that the directional characteristics of the combined signal deviate from the component signals. The TV antenna system also has two antennae which receive the broadcast and output two TV signals. These are combined with a given phase difference. They are also combined with a second, different, phase difference. A diversity unit selects the combined signal allowing best reception and feeds this to a TV receiver. USE/ADVANTAGE - Glass mounted vehicle antenna. Good reception of signals coming from all directions, whether horizontally or vertically polarised, without requiring modification of antenna.

Description

The invention relates to an FN (frequency modulated) transmission supply antenna device for use in motor vehicles for receiving FM transmissions or radio transmissions through diversity reception and on a TV (television or tele vision) transmission antenna device for use with Motor vehicles to receive TV broadcasts through Diversity reception.

Fig. 1 of the accompanying drawings shows a conventional FM transmission antenna device in an automobile, such as disclosed in Japanese Patent Laid-Open Publication No. 58-70646.

As shown in Fig. 1, the conventional FM transmission antenna device comprises an inverted T-shaped main antenna 202 for receiving FM transmissions and an auxiliary antenna 203 which has a double function as a defroster, the main and auxiliary antennas 202 , 203 are arranged on a glass pane 201 of a motor vehicle rear window. Signals from the main and additional antennas 202 , 203 are fed to a diversity radio receiver 204 .

The main antenna 202 has a large directional pattern with respect to horizontally polarized FM transmission waves in a horizontal plane orthogonal to the direction of travel of the motor vehicle. The additional antenna 203 has a large directional pattern in a horizontal plane in the direction of travel of the motor vehicle. Therefore, the diversity radio receiver 204 can effectively receive radio waves by selecting one of the output signals from the main and auxiliary antennas 202 , 203 whichever is higher regardless of the direction from which the radio waves reach the motor vehicle.

The conventional FN transmission antenna device shown in Fig. 1 enables the diversity radio receiver 204 to receive the one with the higher level from the signals of the main and auxiliary antennas 202 , 203 different directional image. However, the conventional FN transmission antenna device is not able to provide a sufficiently non-directional response to radio waves that come from different directions to the motor vehicle. Since the FM antenna device has a different directivity pattern, which depends on whether the received FN transmission radio wave is vertically or horizontally polarized, it is also unable to provide a necessarily undirected response to radio waves that come from different directions in one of the reach the motor vehicle at different polarization levels.

Fig. 2 of the accompanying drawings shows a conventional TV transmission antenna device in a motor vehicle such as that disclosed in Japanese Utility Model Laid-Open No. 63-129307, for example.

As shown in FIG. 2, the conventional TV transmission antenna device has four antennas 211 , 212 , 213 , 214 , which are arranged on a glass pane of a motor vehicle rear window 210 for receiving TV transmission waves. Heating wires 216 are also arranged on the glass pane 210 of the rear window of the motor vehicle.

TV signals received by antennas 211 , 212 , 213 , 214 are fed to a TV signal amplifier 217 . The TV signal amplifier 217 amplifies the supplied four television signals to a level high enough for processing the television signals by a diversity unit 218 . The amplified television signals are fed to the diversity unit 218 , which selects one of the four television signals, which has a highest S / N ratio, for example, and feeds the selected television signal to a TV receiver 219 . Therefore, the TV receiver 219 is fed with one of the four television signals received under the best conditions.

The conventional TV broadcast antenna device shown in Fig. 2 poses no problem in that any one of the television signals received by the four antennas 211 to 214 is of good quality. However, strict restrictions on the number, shape, size and direction of the antennas, which can be arranged in the limited area on the glass pane 210 of the rear window, can prevent all the television signals received by the four antennas 211-214 from being simultaneously of good quality . The four antennas 211 to 214 are also unable to provide an incorrect directional antenna pattern. If none of the television signals received by the four antennas 211 to 214 is of good quality, the TV receiver 219 is fed with a signal of comparatively good quality among the four television signals. However, since such a television signal of comparatively good quality has an S / N ratio which is below an acceptable value, the TV transmission antenna device cannot achieve good TV transmission reception.

The antenna directivity cannot be changed unless the shape, direction etc. of the antennas is modified. It is practically impossible to modify the shape, direction, etc. of the antennas 211 to 214 on the glass window 210 of the rear window each time the motor vehicle changes course and thus the direction from which the desired television signal reaches the motor vehicle of the motor vehicle changes.

It is therefore an object of the invention to transmit FM antenna device for use in motor vehicles to provide that is able to come from all directions FM transmission radio waves without modification of the antennas  configuration well received, regardless of whether you are polarized vertically or horizontally.

Another object of the invention is a TV broadcast supply antenna device for use in motor vehicles to provide that is able to come from all directions TV signals good regardless of the antenna configuration to recieve.

In one aspect of the invention is an FM broadcast antenna device for use with a force vehicle provided comprising: a main antenna for Receiving an FM broadcast to set off a main FM signal admit an additional antenna to receive the FM broadcast, to output an additional FM signal and a changeable one Phase shifter module to the main FM signal and the FM Additional signal always with a predetermined phase difference to combine between these signals.

Since the changeable phase shifter module that of the main FM main signal received and that of the add-on antenna received additional FM signal with a predetermined Combined phase difference between the two signals, it is possible by selecting a signal from the combined Signal, the main FM signal and the additional FM signal, which was always received in good conditions, one Execute diversity reception. Since the main FM signal and the additional FM signal with the phase difference between them can be combined in such a way that the directional character The characteristics of the combined signal differ from those of the Distinguish between the main and additional antennas, the FM Transmission antenna device from all directions on Motor vehicle incoming FM transmission radio waves well receive.

If the FM main and auxiliary antenna essentially the have the same directional characteristics, or if only that combined signal and the main FM signal are sufficient  FM transmission radio waves coming in all directions capture, so the main FM signal alone directly one Diversity radio receivers are fed and it is not necessary, the additional FN signal to the diversity radio receiver feed. The diversity radio receiver can send a signal select the main FM signal and the combined signal, whichever has a higher level on reception.

In another aspect of the invention, one is FM transmission antenna device for use with a Motor vehicle provided, comprising a main antenna for Receiving an FM broadcast to cancel a main FM signal give an additional antenna to receive the FM transmission, to output an additional FM signal, a changeable one Phase shifter module to the main FM signal and the FM Additional signal with a predetermined phase difference to combine between these signals, and a Diversity circuit for effecting diversity reception an output signal from the changeable phase shift module and to change the phase difference if the Level of one of the changeable phase shifter module generated combined signal lower than a vorbe is the right value.

The directional characteristics of the combined signal from the changeable phase shifter module are changed by the phase difference of the changeable phase shifter module is changed. Therefore, the diversity circuit can Phase difference automatically to an optimal value at Set signal reception.

In another aspect of the invention, one is TV broadcast antenna device for use with a Motor vehicle provided, comprising: a first antenna for Receiving a television broadcast to a first television output signal, a second antenna to receive the TV broadcast to extract a second TV signal ben, a first changeable phase shifter module  Output of the first and second television signals with one predetermined phase difference between these signals, a first combining circuit for combining the one of the first changeable phase shifter module with the first predetermined phase difference output first and second television signal and to output the combined first and second television signals as a first combi nated signal, a second changeable phase shifter module for outputting the first and second television signals with a second predetermined phase difference between them Signals, a second combining circuit for combining of the second changeable phase shifter module with the second predetermined phase difference, he output and second television signal and to output the combi nated first and second television signal as a second combined signal, and a diversity unit to make one the first and second combined signals for the better Select signal reception and the selected combined Feed the signal to a TV receiver.

If the first and second phase difference are like this that the directional characteristics of the first and second combined signal complement each other, then assign either the first combined signal or the second combined signal regarding from all rich of upcoming television broadcasts sufficient Reception gain on. The diversity unit chooses for bes seren signal reception the combined signal and carries it to the TV receiver.

The diversity unit can be a device for receiving the first television signal and / or the second television signal in addition to the first and second combined signals include an optimal signal from the received Selects signals and feeds them to the TV receiver.

The diversity unit can get an optimal signal from the first and second combined signal and the first  and / or select the second television signal and switch it off feed selected signal to the TV receiver. Due to the Directional characteristics of the first and second combined Signal by the directional characteristics of the first and second television signal allows an overlap ver equally weak sensitive directions a good one Television broadcast reception.

In another aspect of the invention, one is TV broadcast antenna device for use with a Motor vehicle provided, comprising a first antenna for Receiving a television broadcast to a first television output signal, a second antenna to receive the TV broadcast to broadcast a second TV signal give a changeable phase shifter module for output of the first and second television signals with a vorbe agreed phase difference between these signals, one Combining circuit for combining the change from the ble phase shifter module with the predetermined phases difference output first and second television signal and to output the combined first and second Television signal as a combined signal, and one Diversity circuit for changing the phase difference in order optimize the combined signal when the combined Signal is not suitable for good signal reception.

The of the changeable phase shifter module with the Phase difference output first and second television signals are combined by the combining circuit. If a combined signal as not suitable for a good one TV signal reception determined by the diversity circuit was changed, the diversity circuit changed in the possible phase shifter module set phase difference, to optimize the combined signal. If changed the conditions for receiving television broadcasts have changed, such as after a movement of the motor vehicle, the diversity circuit changes the phase difference to to maintain the conditions for good signal reception.

The above and other objectives, details and advantages of the present invention will be apparent from the following detailed description of preferred embodiment Forms of the invention become clear when these in Ver can be read with the attached drawings.

Fig. 1 is a schematic view - partially in block form - of a conventional FM transmission antenna device in a motor vehicle;

Fig. 2 is a schematic view - partially in block form - of a conventional TV transmission antenna device in a motor vehicle;

Fig. 3 is a block diagram of an embodiment of an FM transmission antenna device in an automobile according to the present invention;

Fig. 4 is a circuit diagram of an FM main antenna matching circuit or FM auxiliary antenna matching circuit in the FM transmission antenna device shown in Fig. 3;

Fig. 5 is a circuit diagram of another FM main antenna matching circuit or FM auxiliary antenna matching circuit;

Fig. 6 is a circuit diagram of another FX main antenna matching circuit or FM auxiliary antenna matching circuit;

Fig. 7 (A) is a circuit diagram of one of the phase control circuits in the FM transmission antenna device shown in Fig. 3;

Fig. 7 (B) is a diagram illustrating the operation of the phase control circuit shown in Fig. 7 (A);

Fig. 8 (A) is a circuit diagram of the other phase control circuit in the FM broadcast antenna device shown in Fig. 3;

Fig. 8 (B) is a diagram illustrating the operation of the phase control circuit shown in Fig. 8 (A);

Fig. 9 is a diagram showing the operation of a variable phase shifter module in the FM transmission antenna device shown in Fig. 3;

Fig. 10 is a block diagram of another embodiment of an FM transmission antenna device according to the present invention in a motor vehicle;

Fig. 11 (A) and 11 (B), the operation of the embodiment shown in Figure 10 FM transmission antenna device constitute de diagrams.

Fig. 12 is a block diagram of an embodiment according to the invention a television transmitting antenna means in a motor vehicle;

Fig. 13 is a block diagram of a changeable phase shifter module in the TV broadcast antenna device shown in Fig. 12;

Fig. 14 is a circuit diagram of an RF switch in the variable phase shifter module shown in Fig. 13;

Fig. 15 (A) is a circuit diagram of a phase control circuit in the variable phase shifter module shown in Fig. 13;

Fig. 15 (B) is a diagram illustrating the operation of the phase control circuit shown in Fig. 15 (A);

Fig. 16 (A) is a circuit diagram of another phase control circuit in the changeable phase shifter module shown in Fig. 13;

Fig. 16 (B) is a diagram illustrating the operation of the phase control circuit shown in Fig. 16 (A);

Fig. 17 is a diagram showing the manner in which signals are combined;

Fig. 18 is a block diagram of another embodiment according to fiction, a TV transmission antenna device in a motor vehicle; and

Fig. 19 (A) to 19 (F) are diagrams showing the quantitative together sat directivity images which were obtained by modifi ed phase differences.

As shown in Fig. 3, an embodiment of the invention from an FM transmission antenna device in a motor vehicle comprises an inverted T-shaped main antenna 11 which is arranged on a glass pane 10 of a rear window of a motor vehicle, an additional antenna 12 which is on the glass pane 10 of the rear window is arranged and has a double function as rear window heating or defrosting heating wires, an FM main antenna adaptation circuit 13 , an additional FM antenna adaptation circuit 14 , a changeable phase shifter module 19 and a diversity radio receiver 16 .

A signal received by the main antenna 11 FM main signal 11a is supplied to the FM main antenna matching circuit. 13 A signal received by the auxiliary antenna 12 FM additional signal 12a is supplied to the FM external antenna matching circuit fourteenth

FIG. 4 shows the main FM antenna matching circuit 13 or additional FM antenna matching circuit 14 . As shown in Fig. 4, the FM main antenna matching circuit 13 or FM auxiliary antenna matching circuit 14 has an input terminal 21 , an output terminal 22 and a tuning control terminal 35 to which a tuning voltage Vs is applied.

The FM main antenna matching circuit 13 or additional FM antenna matching circuit 14 also has a DC blocking capacitor 23 for blocking a DC component supplied to the input terminal 21 , a first resonator with variable capacitance 29 , a second resonator with variable capacitance 36 and tuning voltage application resistors 37 , 38 for applying Tuning voltages to the first or second resonator with variable capacitance 29 , 36 .

The first variable capacitance resonator 29 includes a coil 24 , a capacitor 26 , a pair of variable capacitance diodes 27 , 28 , a ground resistor 41 to allow the tuning voltage Vs to be applied to the variable capacitance diodes 27 , 28 may, and a capacitor 42 for grounding the connection between the first and second resonators with variable capaci ity 29 , 36 by a predetermined impedance.

The second variable capacitance resonator 36 includes a coil 31 , a capacitor 32, and a pair of variable capacitance diodes 33 , 34 .

The DC blocking capacitor 23 , the first resonator with variable capacitance 29 and the second resonator with variable capacitance 36 are connected in series between the input and output terminals 21 , 22 .

The variable capacitance diodes 27 , 28 each have cathodes which are connected to the tuning control terminal 35 through the resistor 37 . The variable capacitance diodes 33 , 34 each have cathodes connected to the tuning control terminal 35 through the resistor 38 . Resistor 41 applies a constant bias to the four variable capacitance diodes 27 , 28 , 33 , 34 .

When a tuning voltage (DC voltage) from the diversity radio receiver 16 via phase control circuits in the variable phase shifter module 19 to the tuning control terminals 35 of the FM main or additional antenna matching circuit 13 , 14 is applied, the FM transmission antenna device selects one of a particular transmission station transmitted FM transmission signal. The FM main and additional antenna matching circuits 13 , 14 serve to cancel the reactance components of the antennas 11 , 12 and a reactance component of the diversity radio receiver 16 and also to convert the impedances of the antenna 11 and the diversity radio receiver 16 .

An output signal from the FM main antenna adaptation circuit 13 is supplied via a DC blocking capacitor 39 a to an input terminal of the diversity radio receiver 16 and a phase control circuit 17 in the changeable phase shifter module 19 .

An output signal from the FM additional antenna matching circuit 14 is supplied via a DC blocking capacitor 39 b to a phase control circuit 18 in the variable phase shifter module 19 .

Output signals from the phase control circuits 17 , 18 are combined with one another at a node 20 with a phase difference (described below). A combined signal SP generated at the node 20 is fed to a further input terminal 16 b of the diversity radio receiver 16 . The tuning voltage Vs is also applied to the phase control circuits 17 , 18 .

The FM main antenna matching circuit 13 or FM additional antenna matching circuit 14 can have a circuit arrangement as shown in FIG. 5 or 6. Each of the circuit arrangements shown in FIGS. 5 and 6 has an input terminal 21 , an output terminal 22 , a capacitor 23 and a tuning control terminal 35 which are identical to those shown in FIG. 3. The circuit arrangement shown in FIG. 5 has a variable capacitance resonator 72 , which is composed of a variable capacitance diode 70 and a coil 71 , and a variable capacitance resonator 75 , which consists of a variable capacitance diode 73 and one Coil 74 is composed. The circuit arrangement shown in FIG. 6 has a variable capacitance resonator 80 , which is composed of a coil 78 and a variable capacitance diode 79 , and a variable capacitance resonator 84 , which consists of a coil 82 and a variable capacitance diode 83 is composed, and a resonator with changeable capacitance 88 , which is composed of a coil 86 and a diode with variable capacitance 87 .

The phase control circuit 17 shown in Fig. 3 has a circuit arrangement as shown in Fig. 7 (A). The phase control circuit 17 comprises a coil 43 with an inductance L ₁ and a diode with variable capacitance 44 with a coupling capacitance C ₁ . A signal S ₁ that has passed through the phase control circuit 17 leads in phase as shown in FIG. 7 (B) to a maximum value of π. In Fig. 7 (B), f ₁ denotes a frequency given according to the equation L ₁ C ₁ = (2πf ₁ ) ^-2 . An output signal S1 from the main FM antenna matching circuit 13 is supplied to an input terminal 46 and is output from an output terminal 47 out of phase with the phase of the signal at the input terminal 46 . The tuning voltage Vs generated by the diversity radio receiver 16 is applied to the output terminal 47 . Since the voltage applied to the output terminal 47 tuning voltage Vs 45 can not pass through a DC-blocking capacitor, the diode is biased with changed derbarer capacitance 44 through a resistor 50 in blocking direction. As the frequency of a selected FM transmission signal increases, the tuning voltage Vs. When the applied tuning voltage Vs becomes higher, the coupling capacitance C _{1 of} the variable capacitance diode 44 becomes smaller and the frequency f ₁ becomes higher, with the result that the curve in Fig. 7 (B) moves to the right. The distance that the curve travels in Fig. 7 (B) changes depending on the size of the tuning voltage Vs.

The amount by which the tuning voltage Vs changes depending on the change in the selected frequency is set such that the phase feed X ₁ remains constant based on the graph of FIG. 7 (B). As the frequency of a selected FM transmission signal becomes smaller, the curve in Fig. 7 (B) moves to the left. If the coupling capacitance C _{1 of} the variable capacitance diode 44 is selected in the range from 10 pF to 40 pF, it is prevented that the capacitance C _{3 of} the DC blocking capacitor 45 interferes with the phase control. If the resistance value R _{1 of} the resistor 50 is chosen to be approximately 100 kΩ, the signal S1 input from the input terminal 46 is prevented from passing through the resistor 50 to the output terminal 47 .

The phase control circuit 18 shown in FIG. 3 has a circuit arrangement as shown in FIG. 8 (A). The phase control circuit 18 comprises a coil 48 with an inductance L ₂ and a diode with variable capacitance 49 with a coupling capacitance C ₂ . A signal S2 supplied to an input terminal 51 , which has passed through the phase control circuit 18 , continues in phase as shown in FIG. 8 (B) to a maximum value of π and is output from an output terminal 52 . In Fig. 8 (B), f ₂ denotes a frequency given according to the equation L ₂ C ₂ = (2πf ₂ ) ^-2 . When the tuning voltage Vs is applied to the output terminal 47 , the coupling capacitance C _{2 changes} with the coupling capacitance C ₁ ; the frequency f _{2 also} varies, with the curve moving to the right or left in Fig. 8 (B). The amount by which the tuning voltage Vs changes depending on the change in the selected frequency is set such that the phase lag X ₂ remains constant based on the graph of FIG. 8 (B).

The phase control circuit 17 can have the circuit arrangement shown in FIG. 8 and the phase control circuit 18 the circuit arrangement shown in FIG. 7. Both Pha sen control circuits 17 , 18 may have a circuit arrangement which causes a supplied input signal to lead or lag in phase. The output signal S2 from the additional FM antenna matching circuit 14 can be supplied not only to the phase control circuit 18 , but also to the diversity radio receiver 16 . The supply of the output signal S2 also to the diversity radio receiver 16 is effective in that good signal reception is achieved if the main FM antenna 11 and the additional FM antenna 12 have different directional characteristics.

The diversity radio receiver 16 is arranged such that it selects a reception signal of better quality from the reception signals which have been fed to its input terminals 16 a, 16 b. The diversity radio receiver 16 is also arranged so that it can supply the tuning voltage Vs, which can be applied to a local oscillator or local oscillator, from the input terminal 16b to external circuits.

The operation of the FM transmission antenna device will described below.

The user of the FM transmission antenna device operates the diversity radio receiver 16 to select a desired FM transmission station. The diversity radio receiver 16 generates a tuning voltage Vs which is applied to the variable capacitance diodes 27 , 28 , 33 , 34 in the main FM antenna matching circuit 13 . The capacitances of the variable capacitance diodes 27 , 28 , 33 , 34 are varied such that an FM transmission signal of a frequency f _x1 from the selected FM transmission station passes through the FM main antenna matching circuit 13 without any losses. The FM antenna signal adjustment circuit 13 output by the FM main antenna is supplied via the capacitor 39 to the phase control circuit 17 and the diversity radio receiver 16 . The tuning voltage Vs is also applied to the FM additional antenna matching circuit 14 , which operates in the same way as the FM main antenna matching circuit 13 and _applies an output signal S2 of frequency f _x1 to the phase control circuit 18 .

The phase control circuit 17 causes the input signal S1 to frequency X ₁ in phase with the frequency f _x1 as shown in Fig. 7 (B). The phase control circuit 18 causes the input signal S2 to lag in phase with the frequency f _x1 as shown in Fig. 8 (B) by X ₂ . If the signals S1, S2 supplied to the phase control circuits 17 , 18 are in phase, the output signals of the phase control circuits 17 , 18 are shifted by X _D = X ₁ + X ₂ phases.

If a frequency f _x2 that is higher than the frequency f _x1 is selected, the tuning voltage Vs is increased by a predetermined amount and the capacitances C ₁ , C _{2 are} reduced, the frequencies f ₁ , f ₂ increasing. Therefore, the curves in Figs. 7 (B) and 8 (B) are shifted to the right by an interval. The signal output by the phase control circuit 17 continues to advance in phase by X ₁ , the signal output by the phase control circuit 18 continues to follow in phase by X ₂ . Therefore, the phase difference X _D between these signals remains the same as when the frequency f _{x1 is} selected. Due to the effect that the variable capacitance diodes 44 , 49 have on the tuning voltage Vs, the phase difference X _D remains essentially constant with respect to all frequencies in the FM frequency band that can be selected from the diversity radio receiver 16 . The signal output from the variable phase shifter module 19 is supplied to the diversity radio receiver 16 as a combined signal Sp which is generated by combining the signals from the phase control circuits 17 , 18 with the phase difference X _D.

Fig. 9 shows a vector representation of the signal Sp. In Fig. 9, a vector V (S1) has a direction represented by the phase of the signal S1 and a length represented by the level of the signal S1; a vector V (S2) has a direction represented by the phase of signal S2 and a length represented by the level of signal S2. A combined vector V (S1 + S2) is generated by combining the vectors V (S1), V (S2) with the phase difference X _D. The combined vector V (S1 + S2) corresponds to the combined signal Sp and is generated at node 20 .

By optimizing the phase difference X _D with respect to the directional characteristics of the main FM signal, the combined signal Sp has complementary directional characteristics, which leads to the same advantage as if the antenna configuration were modified to have complementary antenna directivity patterns.

In the above embodiment, the two phase control circuits 17 , 18 are used to generate the phase difference X _D. However, the phase difference X _D can be generated by changing the phase of, for example, only the received signal S1. In such a modification, only one phase control circuit is used, and the output signal S2 from the auxiliary FM antenna matching circuit 14 is supplied to the diversity radio receiver as it is in combination with the output signal of the phase control circuit 17 . The variable capacitance diodes in the above embodiment can be replaced with other variable reactance elements. In the above embodiment, while the tuning voltage Vs is applied to the phase control circuits 17 , 18 , any signal that varies depending on the selected frequency can be applied to the phase control circuits 17 , 18 . The circuit arrangement of the phase control circuits can be modified depending on the type of signal used.

Fig. 10 shows another embodiment of an FM transmission antenna device according to the invention in a motor vehicle. The parts shown in FIG. 10, which are identical to those shown in FIG. 3, are identified by the same reference numerals.

The FM transmission antenna device shown in FIG. 10 effects diversity reception, in which only a combined signal Sp supplied via a coaxial cable 60 is used. A diversity radio receiver 61 has a diversity circuit 62 which supplies the phase control circuit 17 in the changeable phase shifter module 19 with a phase control signal Pc to rotate the directional characteristics of an supplied FM transmission signal to rotate as shown in Figs. 11 (A) and 11 (B) to achieve directional characteristics shown. Signals having the directional characteristics shown in Figs. 11 (A) and 11 (B) are applied as temporally successive signals to the diversity radio receiver 16 which compares the supplied signals. Either the FM main antenna matching circuit 13 or the FM additional antenna matching circuit 14 is dispensed with. In this embodiment, since the number of wires used in the FM transmission antenna device can be reduced, the circuits and wires of the FM transmission antenna device can be easily attached to the glass sheet 10 of the automobile rear window. The diversity radio receiver 61 shown in FIG. 3 can be an ordinary diversity radio receiver. However, the diversity radio receiver 61 should be a combination of an ordinary diversity radio receiver and the diversity circuit 62 that generates the phase control signal.

Fig. 12 shows an embodiment of a TV transmission antenna device according to the invention in a motor vehicle.

As shown in FIG. 12, the TV transmission antenna device has a first antenna 130 and a second antenna 131 , both of which are provided for receiving television transmissions, the first and second antennas 130 , 131 on a glass pane 110 of a motor vehicle rear window are arranged. An output signal, ie a first television signal, S11 from the first antenna 130 is fed to changeable phase shifter modules 132 , 133 and a TV signal amplifier 134 ; an output signal, ie a second television signal, S12 from the second antenna 131 is also the changeable phase shifter modules 132 , 133 and the TV signal amplifier 134 leads. The signals S11, S12 comprise television signals in frequency ranges, which include a UHF range, a VHF-H range and a VHF-L range. The TV signal amplifier 134 amplifies the supplied signals to a level high enough for a diversity unit 136 to process them. The diversity unit 136 performs signal processing, such as signal selection, and supplies a TV receiver 137 with a good quality signal.

The changeable phase shifter module 132 has, for example, a circuit arrangement as shown in FIG. 13. In FIG. 13, RF switches 140 , 141 , 142 have a common input terminal 173 , which is connected to the first antenna 130 , and RF switches 143 , 144 , 145 have a common input terminal, which is connected to the second antenna 131 . The RF switches 140-145 have corresponding output terminals connected to corresponding phase control circuits 147 , 148 , 149 , 150 , 151 , 152 . The RF crossovers 140 , 145 are used with respect to television signals in the UHF range, the RF crossovers 141 , 144 with reference to television signals in the VHF-H range and the RF crossovers 142 , 143 with reference to television signals in the VHF-L area.

The RF switches 140 , 141 , 142 have, for example, a circuit arrangement as shown in FIG. 14. The RF switches 140 , 141 , 142 comprise corresponding PIN diodes 156 , 157 , 158 , to which corresponding bias resistors 160 , 161 , 162 and corresponding capacitors 164 , 165 , 166 are connected. The capacitors 164 , 165 , 166 are connected via corresponding output terminals 168 , 169 , 170 to the corresponding phase control circuits 147 , 148 , 149 . The PIN diodes 156 , 157 , 158 have corresponding cathodes, which are connected via a capacitor 172 to the input terminal 173 , which is fed with the television signals from the first antenna 130 . A ground resistor 174 is connected to ground and the node between capacitor 172 and PIN diodes 156 , 157 , 158 . The RF switches 143 , 144 , 145 have the same circuit arrangement as shown in FIG. 14. When a band selection signal Bs for a frequency range containing the frequency of a channel selected by the TV receiver 137 (see FIG. 12) is generated in the TV receiver 137 , the PIN diodes 156 , 157 , 158 alternatively biased and made conductive by the generated band selection signal Bs.

The entire frequency range of television broadcast signals is divided into three frequency ranges by using the RF crossovers 140 , 141 , 142 , since the entire frequency range is a wide range from the VHF range to the UHF range, ie 50 MHz to 800 MHz, with one unused or empty signal range of about 300 MHz between the UHF and VHF range and also with an unused signal range of about a few 10 MHz between the VHF-H range and the VHF-L range. The TV transmission antenna device can process television signals with high accuracy in each of the divided frequency ranges.

The phase control circuit 147 for UHF signals has a circuit arrangement as shown in Fig. 15 (A). The phase control circuit 147 comprises a coil 176 with an inductance L ₁ and a diode with variable capacitance 177 with a coupling capacitance C ₁ . A signal S11 which has passed the phase control circuit 147 leads in phase as shown in Fig. 15 (B) up to a maximum value of π. In Fig. 15 (B), f ₁ denotes a frequency given according to the equation L ₁ C ₁ = (2πf ₁ ) ^-2 . A signal S11 supplied by the first antenna 130 is supplied to an input terminal 178 and output by an output terminal 179 , whereby it is approximately X ₁ ahead of the phase at the input terminal 178 . A tuning voltage (DC voltage) Vs corresponding to the frequency of a selected television signal is applied to the output terminal 179 . Since the tuning voltage Vs cannot pass a DC blocking capacitor 175 , the variable capacitance diode 177 is reverse biased by a resistor 180 . As the frequency of a selected UHF television signal increases, the tuning voltage Vs increases. When the applied tuning voltage Vs becomes higher, the coupling capacitance C _{1 of} the variable capacitance diode 177 becomes smaller and the frequency f ₁ increases, with the result that the curve in Fig. 15 (B) moves to the right. The distance that the curve travels in Fig. 15 (B) changes depending on the size of the tuning voltage Vs. The amount by which the tuning voltage Vs changes depending on the change in the selected frequency is set such that the phase feed X ₁ remains constant based on the graph of FIG. 15 (B). When the frequency of a selected television signal becomes lower, the curve moves to the left in Fig. 15 (B).

If the coupling capacitance C _{1 of} the variable capacitance diode 177 is selected in the range from 10 pF to 50 pF, the capacitance C _{3 of} the DC blocking capacitor 175 is prevented from interfering with the phase control. If the resistance value R _{1 of} the resistor 180 is chosen to be about 100 kΩ, the signal S11 input from the input terminal 178 is prevented from passing through the resistor 180 to the output terminal 179 without being phase controlled.

Each of the phase control circuits 148 , 149 for VHF-H, VHF-L signals has a circuit arrangement as shown in Fig. 15 (A). However, the constants L ₁ , C ₁ are chosen so that the frequencies are in the VHF-H, VHF-L range and the phase advance X _{1 is} maintained.

The phase control circuit 152 has a circuit arrangement as shown in Fig. 16 (A). The phase control circuit 152 includes a coil 181 with an inductor L ₂ and a variable capacitance diode 182 with a coupling capacitance C ₂ . A signal S12 supplied to an input terminal 183 , which has passed through the phase control circuit 152 , follows in phase up to a maximum value of π as shown in FIG. 15 (B) and is output from an output terminal 184 . In Fig. 15 (B), f ₂ denotes a frequency given according to the equation L ₂ C ₂ = (2πf ₂ ) ^-2 . The output signal S12 of the second antenna 131 is supplied to the input terminal 183 and output from the output terminal 184, which is opposite to the phase at the input terminal 183 lags by about _x2. When the tuning voltage Vs is applied to the output terminal 184 , the coupling capacitance C _{2 changes} with the coupling capacitance C ₁ ; the frequency f _{2 also} varies, whereby the curve in Fig. 15 (B) moves to the right or left. The amount by which the tuning voltage Vs varies depending on the change in the selected frequency is set such that the phase lag X ₂ remains constant based on the graph of FIG. 15 (B). Thus, output signals from the phase control circuits in the changeable phase shifter module 132 are combined with one another with a phase difference X _D1 = X ₁ + X ₂ at a node 153 and output as a combined signal SP11 from the changeable phase shifter module 132 .

Each of the phase control circuits 150 , 151 for VHF-H, VHF-L signals has the circuit arrangement shown in Fig. 16 (A). However, the constants L ₂ , C ₂ are chosen so that the frequencies are in the VHF-H, VHF-L ranges and the phase lag X _{2 is} maintained.

If a sufficient phase difference can be generated by one of the phase control circuits 147 , 148 , 149 that produce a phase lead or the phase control circuits 150 , 151 , 152 that generate a phase lag, the other phase control circuits can be omitted. Therefore three phase control circuits can be omitted. Both the phase control circuits 147 , 148 , 149 and the phase control circuits 150 , 151 , 152 can have a circuit arrangement for generating a phase lead or a phase lag. If the amount by which the coupling capacitance of the variable capacitance diodes varies is sufficiently large, each group of phase control circuits 147 , 148 , 149 and phase control circuits 150 , 151 , 152 can be replaced by one or two phase control circuits.

The changeable phase shifter module 133 has the same arrangement as the changeable phase shifter module 132 . However, output signals from the phase control circuits in the changeable phase shifter module 133 have a phase difference X _D2 , which is a combination of X _D1 and π / 4, for example. The phase difference X _D2 can be expressed as X _D2 = (X ₁ + π / 8) + (x ₂ + π / 8), where (X ₁ + π / 8) generated one from a UHF phase control circuit in the variable phase shifter module 133 Phase advance and (X ₂ + π / 8) represents a phase lag generated by a further UHF phase control circuit in the changeable phase shifter module 133 . The other phase control circuits in the variable phase shifter module 133 are also arranged to generate a phase difference X _D2 .

If only the combined signals SP11, SP12 output by the changeable phase shifter modules 132 , 133 can provide sufficient directional characteristics, it is not necessary to supply the signals S11, S12 to the TV signal amplifier 134 and the diversity unit 136 . Such a modification simplifies the wiring of the TV transmission antenna device. In addition, two output signals from the changeable phase shifter module 132 can be combined in an additional combining circuit according to a suitable combining process.

The operation of the TV broadcast antenna device will described below.

Phase differences X _D1 , XD ₂ are chosen such that combined signals SP11, SP12 have complementary Richtcha characteristics. After the phase differences X _D1 , X _{D2 have been} selected, they are kept at constant values in the corresponding changeable phase shifter modules 132 , 133 .

When the TV receiver 137 is operated so that it selects a television signal having a frequency f _x1 in the UHF range, a band selection signal Bs for UHF signals is fed via the resistor 160 to the RF switches 140 , 141 , 142 . The PIN diode 156 is made conductive, the PIN diodes 157 , 158 remain non-conductive. A signal S11 output by the first antenna 130 is fed to the input terminals of the RF switches 140 , 141 , 142 . The signal S11 passes the conductive PIN diode 156 , but is blocked by the non-conductive PIN diodes 157 , 158 . The signal S11, which has passed the PIN diode 156 , is supplied via the capacitor 164 and the output terminal 168 of the input terminal 178 of the phase control circuit 147 for UHF signals.

The phase control circuit 147 causes the input signal of frequency f _x1 to lead X ₁ in phase. When a frequency f _{x2 is} selected that is higher than the frequency f _x1 , the tuning voltage Vs applied to the phase control circuit 147 is increased. As the applied tuning voltage Vs increases, the coupling capacitance C _{1 of} the variable capacitance diode 177 decreases and the frequency f ₁ increases. Therefore, the curve in Fig. 15 is shifted to the right. The television signal of the selected frequency runs exactly at X ₁ in phase at all times.

A signal S12, which has passed the RF crossover 145 , which has been made conductive by the band selection signal Bs for UHF signals, is supplied to the phase control circuit 152 for UHF signals. Since the RF switches 143 , 144 have been made non-conductive, they block the signal S12. Only the television signal of the frequency f _x1 among the television signals, which are contained in the phase control circuit 152 supplied signal 512 is output from the phase control circuit 152 after having been delayed in phase by exactly one of X ₂ different value.

The signals are vectorially combined at node 153 as shown in FIG. 17. The signal S11, which is advanced by X ₁ , corresponds to a vector V (S11). The vector V (S11) has a direction represented by the phase of the signal S11 and a length represented by the level of the signal S11. A vector V (S12) corresponding to the signal S12 also has a direction which is represented by the phase of the signal S12 and a length which is represented by the level of the signal S12. When the two signals S11, S12 are combined with one another with a phase difference X _D1 = X ₁ + X ₂ , a combined signal corresponding to a vector V (S11 + S12) is generated. The combined signal SP11 is output by the changeable phase shifter module 132 .

Likewise, a combined signal SP12, which was generated by combining signals with a phase difference X _D2 = X _D1 + π / 4, is output by the variable phase shifter module 133 . Since the combined signals SP11, SP12 have the corresponding predetermined phase differences X _D1 , X _D2 , one of the signals has a sufficient signal reception gain with respect to television signals reaching the motor vehicle from any direction.

The two combined signals SP11, SP12 and the signals S11, S12 are amplified by the TV signal amplifier 134 and fed to the diversity unit 136 . In Fig. 12, the signals amplified by the TV signal amplifier 134 are denoted by S12A, S11A, SP11A, SP12A. The diversity unit 136 selects one with the highest signal level from the supplied signals S11, S12, SP11, SP12 and feeds the selected signal to the TV receiver 137 . The TV receiver 137 can thus receive the desired television signal under good conditions.

Fig. 18 shows a further execution according to the invention form a television transmitting antenna means in a motor vehicle. The TV transmission antenna device has a changeable phase shifter module 132 A, which has the same circuit arrangement as the changeable phase shifter module 132 shown in FIG. 12. A combined signal SP11, which is generated by combining signals with a phase difference X _D1 and is output by the variable phase shifter module 132 A, is amplified by a TV signal amplifier 134 A and then fed to a diversity circuit 191 . When the level of the input combined signal SP11 is below a vorbe agreed level 191 sends the diversity circuit, a phase control signal to the variable phase shifter module 132 is A. Based on the phase control signal, the pre-voltage in the reverse direction, the Barer to the diodes with Variegated capacity 177 , 182 is varied to change the phase difference X _D1 . In this way, the composite directivity image of the combined signal SP11 is successfully modified as shown in Figs. 19 (A) to 19 (F).

It is assumed that the directivity pattern of the combined signal generated with the phase difference X _D1 is inclined with respect to the direction of travel of the motor vehicle at an initial angle R as shown in FIG. 19 (A). When a television signal of a frequency f _{x1 reaches} the motor vehicle from the front left at substantially 45 ° to the direction of the motor vehicle, the level of the combined signal SP11 is small, depending on the size of an induced voltage level LA. When the signal level is below a predetermined signal level in the diversity circuit 191 , the diversity circuit 191 outputs the phase control signal to the phase difference X _D1 to generate successive, as in Figs. 19 (B), 19 (C) , 19 (D), 19 (E) and 19 (F) shown to vary directional images. In Figs. 19 (B) and 19 (C), the level of the combined signal SP11 is low because the induced voltage level LA is low. As shown in Fig. 19 (D), when the level of the combined signal SP11 is equal to or exceeds the predetermined signal level, the output of the phase control signal can be stopped.

A combined signal SPN generated with the directivity image shown in FIG. 19 (D) is supplied to the television receiver 137 , which thus receives the television signal under good conditions. When the direction from which the television signal of frequency f _{x1 reaches} the motor vehicle subsequently changes when the motor vehicle is moving, the diversity circuit 191 varies the phase difference to keep the level of the combined signal above the predetermined signal level.

In the embodiment shown in FIG. 18, the tuning voltage Vs output from the TV receiver 137 is transmitted to the diversity circuit 191 via a single transmission cable 192 ; The combined signal SPN is also fed to the TV receiver 137 via the transmission cable 192 . Only a changeable phase shifter module 132 A is used, and it is not necessary for the signals S11, S12 from the antennas 130 , 131 to be supplied to the diversity circuit 191 . Therefore, the wiring of the TV transmission antenna device is relatively simple, and the TV transmission antenna device itself has a comparatively simple arrangement.

Except where the television signals are too weak to be received well, the level of the combined signal SPN should exceed a predetermined level by sequentially combining output signals for all phase differences in the variable phase shifter module 132A . Combining output signals to provide each of the directional images shown in Figs. 19 (A) to 19 (F) is equivalent to using as many different antennas as the number of such directivity images. When using two antennas, it is consequently easy to achieve the same signal reception as with the conventional antenna device with four antennas.

The variable capacitance diodes in the embodiments shown in FIGS. 12 and 18 can be replaced with other variable reactance elements. As an indication for determining whether the combined signal in the diversity unit or circuit is acceptable or not, an S / N ratio or the like can be used better than the signal level.

In the FM transmission antenna devices shown in FIGS. 3 and 10, the directional images determined by the configurations of the main and additional antenna are simply supplemented without varying their configuration for good reception of horizontally or vertically polarized radio waves coming from all directions. Therefore, if transmissions of motor vehicles of the same type are received with radio waves of different polarization levels, the same advantages as by changing the antenna configuration can be achieved simply by changing the phase difference.

The diversity circuit in the FM transmission antenna device shown in Fig. 10 can automatically vary the phase difference. Therefore, motor vehicles of the same type that are equipped with the FM transmission antenna device can be used abroad without modifications. The FM transmission antenna device is highly practical because it can immediately change the directional pattern as often as desired because the antenna configuration and direction are not mechanically changed.

The TV transmission antenna device shown in FIG. 12 can generate combined signals that have complementary directional characteristics by presetting a suitable phase difference without changing the number, shape, size and direction of the antennas. The TV transmission antenna device is thus able to receive television signals well.

The diversity unit in the TV transmission antenna device shown in FIG. 12 can select an optimal signal from the first and second combined signal and the first and / or second television signal. A coverage of the directional characteristics of the first and second television signals allows good television broadcast reception. The TV broadcast antenna device can generate television signals that have three or more directional characteristics when using two antennas.

In the case of the TV transmission antenna device shown in FIG. 18, if a combined signal is determined to be unsuitable for good television signal reception by the diversity circuit, the diversity circuit varies the phase difference set in the changeable phase shifter module, thereby thereby the combined signal to optimize. As a result, the TV broadcast antenna device can receive TV signals well even if the conditions for receiving TV broadcasts have changed upon movement of the automobile. A change in the directional characteristics of the combined signals is equivalent to using as many different antennas as the number of directional characteristics that can be combined. Since it is not necessary to set an appropriate phase difference in advance, which is the case with the FM transmission antenna devices shown in FIGS. 3 and 10, the TV transmission antenna device shown in FIG. 18 is very practical. Insofar as it is not necessary for the first and second television signals to be applied to the TV receiver as in the TV transmission antenna device shown in Fig. 12, the wiring between the TV receiver and other circuits is simplified. The TV broadcast antenna device shown in Fig. 18 is simple as a whole because it uses only one changeable phase shifter module.

Although what has currently been described as the before has been described drafted embodiments of the invention is considered to understand that the invention in other special Shapes can be done without the essentials Deviate features of the invention. The present Embodiments are therefore considered in all respects as the Serving representation and viewed as not limiting. The scope of the invention is illustrated by the appended An  say better than from the previous description shown.

An FM transmission antenna device for use with a motor vehicle has a main antenna for reception an FM broadcast to output a main FM signal, an additional antenna to receive the FM broadcast to Output additional signal, and a changeable phase shift module for combining the main FM signal and the FM Additional signal with a always predetermined phase difference between these signals. The changeable phase shifter module combines the FM received from the main antenna Main signal and the FM signal received by the additional antenna Additional signal with a predetermined phase difference between this. The FM transmission antenna device can thus effecting diversity reception by sending out a signal the combined signal, the main FM signal and the FM Additional signal selects whichever under good loading conditions was received. Since the main FM signal and FM additional signal with the phase difference between them can be combined with each other in such a way that the directional character characteristics of the combined signal from those of the main and additional antenna may differ, the FM transmission antenna neneinrichtung from all directions to the motor vehicle incoming FM transmission radio waves well received.

Claims (5)

1. FM transmission antenna device for use in a motor vehicle, comprising:
a main antenna for receiving an FM broadcast to output a main FM signal,
an auxiliary antenna for receiving the FM broadcast to output an auxiliary FM signal, and
a changeable phase shifter module to always combine the main FM signal and the additional FM signal with a predetermined phase difference between these signals. 2. FM transmission antenna device for use in a motor vehicle, comprising:
a main antenna for receiving an FM broadcast to output a main FM signal,
an additional antenna for receiving the FM transmission in order to output an additional FM signal,
a changeable phase shifter module to combine the main FM signal and the additional FM signal with a predetermined phase difference between these signals, and
a diversity circuit for causing diversity reception of an output signal from the variable phase shifter module and for changing the phase difference when the level of a combined signal generated by the variable phase shifter module is lower than a predetermined value. 3. A TV broadcast antenna device for use in a motor vehicle, comprising:
a first antenna for receiving a television broadcast to output a first television signal,
a second antenna for receiving the television broadcast to output a second television signal,
a first changeable phase shifter module for outputting the first and second television signals with a predetermined phase difference between these signals,
a first combining circuit for combining the first and second television signals output by the first changeable phase shifter module with the first predetermined phase difference and for outputting the combined first and second television signals as a first combined signal,
a second changeable phase shifter module for outputting the first and second television signals with a second predetermined phase difference between these signals,
a second combining circuit for combining the first and second television signals output from the second changeable phase shifter module with the second predetermined phase difference and for outputting the combined first and second television signals as a second combined signal, and
a diversity unit to select one of the first and second combined signals for better signal reception and to supply the selected combined signal to a TV receiver. 4. TV transmission antenna device according to claim 3, characterized in that the diversity unit means includes, in addition to the first and second combined signal the first television signal or / and to receive the second television signal and order from the received signals to select an optimal signal and feed the TV receiver. 5. A TV broadcast antenna device for use in a motor vehicle, comprising:
a first antenna for receiving a television broadcast to output a first television signal,
a second antenna for receiving the television broadcast to output a second television signal,
a changeable phase shifter module for outputting the first and second television signals with a predetermined phase difference between these signals,
a combining circuit for combining the first and second television signals output from the changeable phase shifter module with the predetermined phase difference and for outputting the combined first and second television signals as a combined signal, and
a diversity circuit for changing the phase difference to optimize the combined signal when the combined signal is not suitable for good signal reception.