JPH07245516A - Antenna switching on-vehicle antenna - Google Patents

Abstract

PURPOSE:To form a new antenna as a combination of single antenna elements by separating electrically the antenna into plural antenna elements CONSTITUTION:A 1st television antenna 3 and a 2nd television antenna 4 is switched as a single antenna respectively and a balun 2 comprising coils L1, L2 is connected to the antennas 3, 4 and a 3rd reception signal is extracted from other terminals (b), (d) of the balun 2. It is considered that a new antenna being a 3rd antenna acting the 1st antenna 3 like a radiation pattern antenna and acting the 2nd antenna 4 like a ground pattern antenna is obtained through the action of the balun 2 suppressing passing of a common mode current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna-switching type vehicle-mounted antenna adapted to obtain a larger number of received signals than two antennas from two or more antennas.

[0002]

2. Description of the Related Art As a conventional antenna of this type, there is, for example, a window glass antenna device (Japanese Patent Application No. 5-324841) filed by the present applicant. FIG. 10 is an overall configuration diagram of a conventional window glass antenna device (Japanese Patent Application No. 5-324841).

This window glass antenna device 101 comprises a window glass 102 with an antenna in which a plurality of antennas are arranged on a window glass 102a of an automobile, and a switch means 104 for selecting a signal to be inputted to a wide band amplifier 103.

The window glass 102 with an antenna is provided with two systems of TV receiving antennas 105 and 106 and an AM / FM radio receiving antenna 107. These antennas 105, 106 and 107 are vehicle body grounded antennas. Further, the first television receiving antenna 105 is formed with a dedicated antenna pattern, and the second television receiving antenna 106 uses the anti-fog heater wire 108.

Received signals taken out from the power supply terminals 105a and 106a of the television receiving antennas 105 and 106 are supplied to the input terminals 104a and 104b of the switch means 104 through the power supply cables 105b and 106b.

The switch means 104 includes switching diodes D101 and D102 provided corresponding to the respective television receiving antennas 105 and 106, and resistors R101 to R101 for supplying a direct current to these diodes D101 and D102. It is composed of R104 and DC blocking capacitors C101 to C104. Terminal 104c,
104d is a switching control terminal.

Each of the resistors R101 to R104 is set to a high resistance value so as not to attenuate the received signal, and each capacitor C
The capacitance values of 101 to C104 are set so that the impedance becomes sufficiently low in the frequency band of the received signal.

The output 104e of the switch means 104 is supplied to the amplifier 103, and the reception signal amplified by the amplifier 103 is supplied to a television receiver (not shown) via the DC blocking capacitor C105.

According to this window glass antenna 101, the signal of the first television receiving antenna 105 or the second television receiving antenna 106 arranged on the window glass 101 is sent to the switch means 104 as the control signal 104c or 104.
In addition to inputting d alone to take out, the control signals 104c and 104d are simultaneously input to electrically couple the first antenna 102 and the second antenna 103 and take out a combined signal of these antennas. It was

[0010]

However, although a plurality of antennas could be electrically coupled to extract a composite signal, a plurality of antennas are electrically separated to form a new antenna as a combination of individual antenna elements. There was nothing I did. Therefore, an object of the present invention is to provide an antenna switching type vehicle-mounted antenna in which a plurality of antennas are electrically separated and a new antenna is formed as a combination of individual antenna elements.

[0011]

In order to solve the above problems, the present invention provides a set of coils for suppressing passage of a common mode current according to claim 1, wherein one end of one coil is a first coil.
Connected to the second antenna, one end of the other coil is connected to the second antenna, the other end of the other coil is grounded, and one of the first antenna, the second antenna, and the other end of the one coil is connected. It is characterized in that a changeover switch means for connecting one of them to the receiver side is provided.

[0012] In claim 2, a third antenna or more antennas are provided, and the changeover switch means is any one of these antennas and the other end of the one coil.
One can be switched to connect to the receiver side.

[0013]

According to the first aspect of the present invention, the reception signals of the first antenna or the second antenna composed of the vehicle body ground and the antenna wire are input to the receiver side, respectively, and the first antenna and the second antenna are connected. A reception signal of a new non-grounded antenna, which is composed of two antennas and is not based on vehicle body grounding, is input to the receiver side. That is, a new antenna can be obtained by electrically separating the first antenna and the second antenna and combining the single antenna elements.

According to the second aspect of the present invention, even with three or more antennas, a new antenna that is one more than the number of antennas can be obtained. In addition, as the new antenna, a new non-grounded antenna which is composed of the first antenna and the second antenna and does not depend on the vehicle body ground can be obtained.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, the vehicle-mounted antenna of claim 1 will be described. FIG. 1 is a circuit diagram of a main part of a first embodiment of an antenna switching type vehicle-mounted antenna according to the present invention.

The on-vehicle antenna 1 includes a pair of coils 2 and
It is composed of a first television receiving antenna 3, a second television receiving antenna 4, three-contact changeover switch means 5, coupling capacitors C1 and C2, and power feeding terminals P1 and P2. Then, one end a of one coil L1 is connected to the connection terminal 3a of the first television receiving antenna 3 via the capacitor C1, and one end c of the other coil L2 is used for receiving the second television via the capacitor C2. It is connected to the connection terminal 4a of the antenna 4 and the other end d of the other coil L2 is grounded to the vehicle body. Further, the changeover terminal e of the changeover switch means 5 is connected to the connection terminal 3a of the first television receiving antenna 3, and the changeover terminal f of the changeover switch means 5 is connected to the connection terminal 4a of the second television receiving antenna. , The changeover terminal g of the changeover switch means 5 has the other end b of one coil L1.
, And the common terminal h of the changeover switch means 5 is connected to the power supply terminal P1. The power supply terminal P2 is grounded to the vehicle body.

The coil 2 is a so-called balun. Generally, a balun is an impedance converter used for balanced / unbalanced conversion, but the balun according to the present invention suppresses passage of an in-phase current, that is, a so-called float balun or a sorter balun. -A-balun). This coil (hereinafter referred to as balun) 2 does not particularly affect the current when the phase difference between the current flowing through the coil L1 and the current flowing through the coil L2 is 180 degrees, but the phase difference is 0 degrees (that is, in-phase). In the case of (current), it has the effect of suppressing the passage of current. In this embodiment, as the balun 2, a toroidal core (not shown) in which two wires are bifilar wound is used. However, the coil is not limited to the coil wound on the toroidal core, and the balun may be formed by, for example, an air core coil.

It is desirable that the inductance of each of the coils L1 and L2 be set within the range of 10 to 50 μH. In the present embodiment, as an example, both the coils L1 and L2 are set to 25 μH. As the toroidal core, a core material μs850 was used as an example.

2 to 4 are schematic explanatory views showing the relationship between the switch changeover terminal and the television receiving antenna. FIG. 2 shows the case where the changeover switch means 5 is connected to the changeover terminal e. In this case, only the reception signal of the television receiving antenna 3 is input to the power feeding coaxial cable 6 via the power feeding terminals P1 and P2.

FIG. 3 shows the case where the changeover switch means 5 is connected to the changeover terminal f. In this case, only the reception signal of the television receiving antenna 4 is input to the power feeding coaxial cable 6 via the power feeding terminals P1 and P2.

FIG. 4 shows the case where the changeover switch means 5 is connected to the changeover terminal g. In this case, the reception signal of the television receiving antenna 3 and the coil L1 are transmitted via the coil L1.
Both of them and the reception signal of the television receiving antenna 4 via 2 are input to the feeding coaxial cable 6 via the feeding terminals P1 and P2.

Moreover, since the in-phase current of the currents flowing through the coils L1 and L2 is suppressed, the television receiving antenna 3
And 4 are connected to the coaxial cable 6 in an electrically separated state. Therefore, the television receiving antenna 3 and the television receiving antenna 4 constitute one new antenna W as an independent element (pattern).

In the case of this antenna W, it is considered that the television receiving antenna 3 constitutes a radiation pattern and the television receiving antenna 4 constitutes a grounding pattern.

Therefore, in the case of the vehicle-mounted antenna 1, the vehicle-body grounded television reception single antenna 3, the vehicle-body grounded television reception single antenna 4, and the non-grounded television reception antennas 3 and 4 are used. It is possible to switch to a total of three types of new antennas W thus created.

Next, the on-vehicle antenna of claim 2 will be described. FIG. 5 is a circuit diagram of an essential part of a second embodiment of an antenna switching type vehicle-mounted antenna according to the present invention.

This on-vehicle antenna 11 is obtained by adding a television receiving antenna 12 to the on-vehicle antenna 1 of the first embodiment and changing the changeover switch means 5 to a changeover switch means 13 having four contacts. That is, the connection terminal 12a of the television receiving antenna 12 is connected to the fourth switching terminal i of the changeover switch means 13. The other television receiving antennas 3 and 4 and the switching terminals e, f and g are connected in the same manner as in the first embodiment, and the description thereof will be omitted.

Therefore, in the case of the vehicle-mounted antenna 11, the vehicle-body-grounded television reception single antenna 3, the vehicle-body-grounded television reception single antenna 4, the vehicle-body-grounded television reception single antenna 12, and the non-grounded antenna. A total of 4 new antennas W, which are composed of the TV receiving antennas 3 and 4
You can switch to a seed antenna.

Even if an antenna other than the television receiving antenna 12 is further added, a new antenna which is one more than the number of antennas, that is, a non-grounded television receiving antennas 3 and 4 is added. A unique antenna W is obtained.

Next, a specific structure of the vehicle-mounted antenna 11 of the second embodiment will be described. FIG. 6 is an antenna pattern diagram of the second embodiment, and FIG. 7 is a dimensional diagram of the antenna pattern. If the antenna 12 is removed from the second embodiment, the antenna pattern becomes substantially the same as that of the first embodiment. or,
The size of the antenna pattern is an example, and the size is not limited to this.

The on-vehicle antenna 11 has a rear window glass 20.
And a television receiving antenna 12 which shares the upper anti-fogging heater 21 disposed in the left and right direction with the antenna, and a television receiving antenna 4 which is disposed above the left side of the antenna 12.
The television receiving antenna 3 disposed above the antenna 4 along the upper edge of the window glass 20 and the television receiving antenna 12 have a main part disposed on the upper right side and a part extending on the upper left side. The main antenna 21 for AM / FM provided and the sub-antenna 23 for AM / FM in which the lower anti-fog heater 22 is also used as an antenna are configured.

A connection terminal 3a for the television receiving antenna 3 and a connection terminal 4a for the television receiving antenna 4 are provided on the upper left side of the window glass 20, and the main antenna 21 for AM / FM is provided on the upper right side of the window glass 20. The connection terminal 21a is provided, and the connection terminal 23a of the AM / FM sub-antenna 23 is provided on the lower right side of the window glass 20.

That is, the vehicle-mounted antenna 11 is composed of a television diversity antenna including three television antennas 3, 4 and 12 and an AM / FM diversity antenna including two AM / FM antennas. It is an antenna with two diversity antennas. Since the structure of the diversity circuit is similar to that of the conventional diversity antenna, illustration and circuit description thereof are omitted.

Further, in the present embodiment, as the antenna, the one in which the antenna wire is arranged on the window glass is used, but the present invention is not limited to this antenna, and for example, it is attached to the film-like antenna attached to the window or the vehicle body. It is also possible to use a whip antenna.

Further, in the second embodiment, the television receiver antennas 3, 4 and 12 constitute a switchable vehicle-mounted antenna.
It is also possible to configure a switchable vehicle-mounted antenna with the M / FM receiving antennas 21 and 23.

Next, each circuit of the second embodiment will be described. First, the antenna and the changeover switch means will be described. FIG. 8 is a circuit diagram of the antenna and the changeover switch means. In the circuit diagram, the antennas 3, 4, 12 according to the present invention are shown.
Although the antennas 21 and 23 are omitted and the antennas 21 and 23 are omitted, the antennas 3 and 4 can be replaced with the antennas 21 and 23.

The on-vehicle antenna 11 has power supply terminals P1 and P2.
Is connected to a receiving amplifier 30 described later via. or,
The vehicle-mounted antennas 3, 4, 12 are provided on the rear window glass 20, and the balun 2, the changeover switch means 13, and the reception amplifier 30 are provided, for example, below a rear tray (not shown) in the vehicle compartment.

The connection between the antennas 3, 4, 12 and the balun 2 is as described above, and the changeover switch means 13 will be described. As the changeover switch means 13, specifically, a combination of four contact mechanical changeover switches S1 to S4 and diodes D1 to D4 is used. These switches S1 to S4
Is a known mechanical changeover switch configured to close only one of the four contacts. Further, the received signals at the time of switching are the diodes D1 to D corresponding to the respective switches S1 to S4.
It is input to the power supply terminals P1 and P2 via any one of the four. Further, capacitors C3, C4, C5 connected in series to the diodes D1, D2, D4 respectively are for passing the reception signal,
The resistors R1 to R8 are for bias. The resistor R9 is also for bias. Also, + B is at the open end of resistors R5 to R9.
A voltage is applied.

First, the switch S1 is closed (ON), S2.
When S4 is open (OFF), the anode side of the diode D1 has a low level and the anode sides of the diodes D2 to D4 have a high level, so that only the diode D1 is conductive. Therefore, only the signal received by the antenna 12 is fed to the power supply terminal P.
1 and P2.

Further, the switch S2 is closed (ON), S1 and S
When S3 and S4 are open (OFF), the anode side of the diode D2 becomes low level and the diodes D1, D3 and D4
Since the anode side of is at a high level, only the diode D2 is conductive. Therefore, only the reception signal of the antenna 3 is input to the power supply terminals P1 and P2.

Further, the switch S3 is closed (ON), S1 and S
When S2 and S4 are open (OFF), the anode side of the diode D3 becomes low level and the diodes D1, D2 and D4
Since the anode side of is at a high level, only the diode D3 is conductive. Therefore, in this case, since the balun 2 is connected in series with the diode D3, the reception signals of the antenna 3 and the antenna 4 are input to the power supply terminals P1 and P2. Moreover, since the in-phase current of the currents flowing through the coils L1 and L2 is suppressed, it is considered that the antenna 3 functions as a radiation pattern and the antenna 4 functions as a ground pattern.

Further, the switch S4 is closed (ON), S1 to S
When 3 is open (OFF), the anode side of the diode D4 becomes low level and the anode sides of the diodes D1 to D3 become high level, so that only the diode D4 conducts.
Therefore, only the reception signal of the antenna 4 is fed to the power supply terminals P1, P
Entered in 2.

Instead of these switches S1 to S4, a high level or low level signal may be directly applied to the switch switching terminals S1a to S4a. In this case, the diode becomes conductive when a low level signal is applied. Also, a switching circuit using transistors instead of the diodes D1 to D4 may be used. Although these switch controls are actually performed by a diversity controller (not shown), they are not related to the present invention, and therefore illustration and description thereof will be omitted.

The circuit composed of the resistor R10 and the capacitors C6 and C7 is a power supply circuit having a noise prevention function when the power supply is turned on and off.

Next, the receiving amplifier 30 will be described. FIG. 9 is a circuit diagram of the receiving amplifier. The receiving amplifier 30 includes a trap circuit 31, a switching circuit 32, an amplifier circuit 33, and an AGC circuit 34.

The trap circuit 31 includes coils L10 and L1.
1 is a publicly known trap circuit for attenuating a predetermined frequency signal composed of 1 and capacitors C10 to C12.

The switching circuit 32 includes a diode D1.
0, D11 and resistors R11 to R13 are well-known switching circuits, and a low level voltage is applied to an input terminal P3 provided at one end of the resistor R11 and an input terminal P4 provided at one end of the resistor R13. If diode D
Both 10 and D11 become conductive, and the reception signal from the antenna is input to the amplifier circuit 33. On the other hand, when a high level voltage is applied to both terminals P3 and P4, the diodes D10 and D
Both 11 are non-conductive, and the received signal from the antenna is not input to the amplifier circuit 33.

The amplifier circuit 33 includes an NPN transistor Q1, a coupling capacitor C13 connected to the base side of the transistor Q1, and bias resistors R14 and R15.
A receiving signal passing capacitor C14, bias resistors R16 and R18 and a high frequency choke L12 connected to the collector side, and a bias resistor R1 connected to the emitter side.
7 and bypass capacitor C15, and capacitor C1
It is a known amplifier circuit configured by an output terminal P5 connected to the other end of the amplifier 4. A + B voltage is applied to the other ends of the resistor R14 and the high frequency choke L12. The output terminal P6 is a ground side terminal.

AGC (Auto Gain Controller)
ol) circuit 34 includes NPN transistors Q2 and Q3.
And noise prevention capacitors C16 and C17 connected to the base side of the transistor Q2 and a detection diode D1.
2, a backflow prevention diode D13 and a coupling capacitor C18, and bias resistors R19 and R2 connected between the collector of the transistor Q2 and the base of the transistor Q3.
0 and a noise prevention capacitor C19, and a bypass capacitor C connected to the emitter side of the transistor Q3.
It is a known AGC circuit composed of 20 and a high frequency choke L13. The emitter of the transistor Q2 is grounded, and the + B voltage is applied to the collector of the transistor Q3 and the cathode of the diode D13.

Further, by connecting the output terminal of the capacitor C11 and the anode of the diode D10, the trap circuit 31 and the switching circuit 32 are coupled, and the diode D
The switching circuit 32 and the amplifier circuit 33 are coupled by connecting the anode of 11 and the input terminal of the capacitor C13, and the amplifier circuit 33 and the AGC circuit 34 are connected by connecting the other end of the resistor R18 and the other end of the capacitor C18.
Are coupled, and the other end of the high frequency choke L13 and the diode D
By connecting the cathode side of 10, D11, AG
The C circuit 34 and the switching circuit 32 are coupled. Further, the changeover switch means 13 and the trap circuit 31 are coupled to each other via the power supply terminals P1 and P2.

Next, the operation of the receiving amplifier circuit 30 will be described. First, the case where a low level voltage is applied to the input terminals P3 and P4 will be described. In this case, the diodes D10 and D11 are both conductive, and the received signal is input to the amplifier circuit 33 via the trap circuit 31. Then, the received signal is amplified by the amplifier circuit 33, and the amplified received signal is input to the AGC circuit 34 via the resistor R18 and the capacitor C18.

Then, the amplified reception signal is detected by the diode D12, and a DC signal corresponding to the level of the reception signal is input to the base of the transistor Q2. Next, this signal is amplified by the transistors Q2 and Q3 and then input to the base side of the transistor Q1 via the switching circuit 32 to change the gain of the transistor Q1.

That is, since the gain of the transistor Q1 is lowered according to the level of the received signal output from the amplifier circuit 33, a received signal with little distortion can be obtained even in a strong electric field. Further, since the AGC circuit 34 is provided, the amplifier circuit 33 having a higher gain than the conventional one can be used, and the S / N ratio is also improved.

On the other hand, when a high level voltage is applied to the input terminals P3 and P4, the diodes D10 and D11 become non-conductive, and the received signal is not input to the amplifier circuit 33.

As described above, according to the present invention, four antennas can be obtained with three antenna patterns. In addition, a new non-grounded antenna that does not depend on the grounding of the vehicle body, that is, an antenna that is composed of the first antenna and the second antenna, that is, the antenna that is considered to include the radiation pattern and the ground pattern, is obtained as the fourth antenna. be able to. Therefore, it is possible to obtain a four diversity antenna suitable for space saving.

Further, since the changeover switch means is provided, only one receiving amplifier need be provided for each antenna.

Further, since a high gain amplifier can be used as the receiving amplifier, an amplifier having a good S / N ratio can be obtained.

[0057]

According to the first aspect of the present invention, the reception signals of the first antenna or the second antenna composed of the vehicle body ground and the antenna wire are input to the receiver side, respectively, and the first antenna is also used. A reception signal of a new non-grounded antenna that does not depend on the vehicle body grounding and is configured by the second antenna and the second antenna is input to the receiver side. That is, a new antenna can be obtained by electrically separating the first antenna and the second antenna and combining the single antenna elements.

According to the second aspect of the present invention, even with three or more antennas, a new antenna that is one more than the number of antennas can be obtained. In addition, as the new antenna, a new non-grounded antenna which is composed of the first antenna and the second antenna and does not depend on the vehicle body ground can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part of a first embodiment of an antenna switching type vehicle-mounted antenna according to the present invention.

FIG. 2 is a schematic explanatory view showing a relationship between a switch switching terminal of the vehicle-mounted antenna and the antenna (when switched to the first antenna).

FIG. 3 is a schematic explanatory view showing a relationship between a switch switching terminal of the vehicle-mounted antenna and the antenna (when switched to a second antenna).

FIG. 4 is a schematic explanatory view showing the relationship between the switch switching terminal of the vehicle-mounted antenna and the antenna (when the first and second antennas are combined).

FIG. 5 is a circuit diagram of a main part of a second embodiment of the vehicle-mounted antenna.

FIG. 6 is an antenna pattern diagram of the second embodiment of the vehicle-mounted antenna.

FIG. 7 is a dimension diagram of an antenna pattern of the second embodiment of the vehicle-mounted antenna.

FIG. 8 is a circuit diagram of the antenna and the changeover switch means of the vehicle-mounted antenna.

FIG. 9 is a circuit diagram of a reception amplifier of the vehicle-mounted antenna.

FIG. 10 is an overall configuration diagram of a conventional window glass antenna.

[Explanation of symbols]

 1, 11 In-vehicle antenna 2 One set of coil (balun) 3 First television receiving antenna 4 Second television receiving antenna 5, 13 Changeover switch means 12 Third television receiving antenna a, c One end of coil b, d other end of coil e, f, g, i switching terminal h common terminal L1, L2 coil W new antenna

Claims (2)

[Claims] 1. A set of coils for suppressing passage of in-phase current, wherein one end of one coil is connected to a first antenna, one end of the other coil is connected to a second antenna, and the other coil is connected. The other end of the coil is grounded, and changeover switch means for connecting any one of the first antenna, the second antenna and the other end of the one coil to the receiver side is provided. Antenna switching type car antenna. 2. A third antenna or more antennas are provided, and the changeover switch means switches any one of these antennas and the other end of the one coil to connect to the receiver side. An antenna switching type vehicle-mounted antenna according to claim 1, which is capable of