JPS62222709A - Antenna multicoupler circuit - Google Patents

Abstract

PURPOSE:To improve the working efficiency and to reduce the transmission loss by connecting a series resonance circuit resonated to a reception frequency to one input of an equivalent four terminal circuit network whose output is connected to a receiver and connecting the other input to a transmission line connecting an antenna and a transmitter. CONSTITUTION:A receiver 11 is connected to an output terminal 10of a cavity resonator 8 represented as an equivalent four terminal circuit network. Further, transmission lines 2, 3 connecting an antenna 1 and a transmitter 12 are connected to one terminal 5 of the input terminal 4 and a series resonance circuit 7 resonated to a reception frequency fr is connected between the other terminal 6 of the input terminal 4 and ground. A high frequency signal fr induced in the antenna 1 reaches the cavity resonator 8 via the line 2 and goes to the earth via the series resonance circuit 7. When the signal fr is inputted to the cavity resonator 8, it is excited and energy is sent to the output terminal 10 and given to the receiver 11 resultingly. That is, the high frequency signal fr induced in the antenna 1 flows in a closed loop consisting of the antenna 1, the line 2, the input of the cavity resonator 8 and the series resonance circuit 7 mainly and is not given to the transmitter 12 via the line 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antenna sharing circuit when a single antenna is used for both transmission and reception of communication devices having different transmission and reception frequencies.

[Prior art]

Radio stations that use the transmission system, which transmits and receives at the same time, often do not install dedicated antennas for both transmission and reception, but instead use a single antenna for both from an economical standpoint.
Particularly in mobile radio stations, it is common to use both antennas due to space constraints.

If the antenna is also used in such a system, the received radio waves may flow into the transmitter and attenuate the received radio waves, or the output of the transmitter may flow directly to the receiver, masking the received signal, or the receiver may or damage it.

Therefore, conventionally, for example, a common antenna circuit as shown in FIG. 5 has been constructed to eliminate the above-mentioned obstacles.

The figure shows the aircraft-mounted ATC (^lr Traff).
Control) This is a transponder antenna sharing circuit, and in the following explanation, this transponder will be used as an example. ATC) Lance Bonder used in our country has a receiving frequency of 103103O and a transmitting frequency of 11.
is generally set to 109109O.

In the figure, 28 is a transmitter, and the antenna 20 is
It is connected via a coaxial cable 23 with a length of λ1/4 (n+1), and the reception frequency +
, is connected to a series resonant circuit 25 that resonates. on the other hand,
The antenna 20 and receiver 27 are λz/4·(n+1)
A series resonant circuit 26 that resonates at the transmission frequency is connected between the input end of the band pass filter 26 and the ground.
are connected.

Here, λ1 and λ2 represent the wavelengths of the receiving frequency) and the transmitting frequency, respectively, and n represents a positive integer.

Regarding the antenna common circuit configured as described above, the operation at the time of reception will first be explained. A part of the high frequency signal induced in the antenna 20 flows to the communication device 27 via the coaxial cable 22 and the bandpass filter 26. The other side of the received signal reaches the transmitter 28 via the coaxial cable 23, but the length of the coaxial cable 23 is λ1/4·(n+1), and at one end there is a series cable that resonates at the receiving frequency +. Since the resonant circuit 25 is connected, the received signal is sent to the transmitter 28.
There is no inflow to. That is, as is well known, when one end of a λ/4 distributed constant line is terminated by the series resonant circuit 25, the impedance seen from the other end B becomes a high impedance of several ohms, and the receiver 27, which is normally installed at 50 ohms, This is because the impedance becomes extremely high compared to the input/output impedance of the bandpass filter 26. Therefore, the received high-frequency signal mainly flows to the receiver 821, and attenuation caused by the received signal flowing to the transmitter 28 does not pose a problem.

On the other hand, the high frequency signal from the transmitter 28 is sent to the coaxial cable 23
However, at this time, the series resonant circuit 25 does not resonate at the transmission frequency + and becomes high impedance, so no high frequency signal flows there. Also, this transmission high frequency signal tries to flow to the receiver 27, but since a series resonant circuit 24 that resonates with the transmission frequency tag is connected to one end C of the coaxial cable 22, it is similar to the case for the reception signal described above. Regarding the transmission frequency + t, the impedance seen from the other end A of the coaxial cable 22 is Ω.
Since the impedance is much higher than the impedance of the antenna (about 50Ω), the high frequency signal to be transmitted does not flow to the receiver 27, which prevents the reception from being masked or damage to the receiver. can.

[Problems with conventional technology]

In order to obtain the above effect, the length of each coaxial cable 21, 22 must be accurate. Coaxial cable 21.2
The actual length of 2 is calculated from the respective wavelengths λ1 and λ2 and the shortening rate depending on the material, but it is difficult to accurately determine the shortening rate, and there are variations in the presented nominal values, so there is no fixed value. isn't it. Therefore, the length of the coaxial cable cannot be determined with certainty. Therefore, in the past, it was necessary to prepare a large number of coaxial cables of different lengths for each product, select the appropriate one, install it, and adjust it repeatedly to select a coaxial cable that would produce a better effect than the specified one, which resulted in extremely poor work efficiency. It was something.

Therefore, it is impossible to satisfy the maximum functionality that the antenna common circuit can originally have, and it has been necessary to be satisfied as long as the antenna has an effect above a certain level.

Furthermore, the length of the coaxial cable 22.23 is also
In addition to the length required for the layout due to the arrangement of
/4 (n + 1) length must be considered, which is longer than the length for connection purposes only, and necessarily
This method has a problem in that the loss of the received high-frequency signal becomes large.

[Purpose of the invention]

The present invention was made to eliminate the drawbacks of the conventional antenna sharing circuit, and an object of the present invention is to provide an antenna sharing circuit with high working efficiency and low transmission loss.

[Structure of the invention]

In order to solve the above problem, this invention connects a series resonant circuit that resonates at the receiving frequency to one input terminal of an equivalent four-terminal network whose output terminal is connected to a receiver, and connects the other input terminal to one input terminal of an equivalent four-terminal network. The configuration is such that it is connected to a transmission line that connects the antenna and the transmitter.

[Effect]

According to the present invention, with the above configuration, the high frequency signal received by the antenna flows through the series resonant circuit and reaches the receiver via the four terminal network, but the output of the transmitter is A closed loop is not formed for the input end of the four-terminal network, and the signal flows only to the antenna and does not flow to the receiver.

〔Example〕

Hereinafter, embodiments of the invention shown in the drawings will be described in detail.

FIG. 1 is a block diagram showing a transponder using an antenna common circuit according to an embodiment of the present invention. In the figure, 8 is a cavity resonator equivalently represented by a four-terminal network, and a receiver 11 is connected to the output terminal 0. An antenna 1 and a transmitter 12 are connected to one side 5 of the input terminal 4.
A series resonant circuit 7 that resonates at the reception frequency + is connected between the other input terminal 4 and the ground.

To first explain the operation of this circuit during reception, the high frequency signal + induced in the antenna 1 reaches the cavity resonator 8 via the transmission line 2 and flows to the ground via the series resonant circuit 7. . The cavity resonator 8 is a parallel resonant circuit that resonates at the frequency (, J.

When input, it is excited and energy is transmitted to the output end 10, and as a result, it flows to the receiver 11. That is, the high frequency signal Jr induced by the antenna 1 is mainly transmitted through the antenna 1. Transmission line 2. The signal flows through a closed loop formed by the input side of the cavity resonator 8 and the series resonant circuit 7, and does not flow to the transmitter 12 via the transmission line 3. Therefore, no problematic attenuation of the received radio waves occurs.

On the other hand, the high frequency signal hole from the transmission line 3.
2 to the antenna 1. At this time, the flow attempts to flow from one side 5 of the input end 4 of the cavity resonator 8 through the input side of the cavity resonator 8 to the series resonant circuit 7, but the series resonant circuit 7 has a transmission frequency of +.

, the impedance is high due to non-resonance, and is much higher than the impedance of the antenna 1 which is about 50Ω or 75Ω in terms of -S, so almost no high frequency signal of + flows into the series resonant circuit 7. Furthermore, the cavity resonator 8
is non-resonant with respect to the frequency scattering hole, and even if some high-frequency signal of the frequency scattering hole flows on the input side, no energy is transmitted to the output side.

Therefore, it is possible to prevent a situation in which the transmission output flows to the receiver 11 and masks reception or damages the receiver 11.

Transmission frequency used for transponder (wa is 1090M)
llz, the reception frequency is 103103O, and the difference between them is 60MHz. If there is a difference of 60Ml1z, the impedance of the series resonator 7 will clearly change between when it resonates and when it does not resonate, and as mentioned above, for the receiving frequency + r, the impedance of the series resonator 7 changes clearly between the antenna ■, the transmission line 2, and the cavity resonance. The input side of the transmitter 8 and the series resonant circuit 7 form a closed loop, and the transmitter 12, the transmission line 3.degree. 2, and the antenna 1 form a closed loop for transmission frequency apertures.

FIG. 2 shows an embodiment in which a parallel two-wire coupler 14 is used instead of the cavity resonator 8 in FIG.
is connected to the receiver via a bandpass filter 13. In this case, since the bandpass filter 13 can eliminate the transmission frequency +, the transmission line 3 of the transmitter 12 may be connected to one end 15 on the input side of the parallel two-wire splicer 14.

Cavity resonator as an equivalent four-terminal network8. Although the explanation has been given using the parallel two-wire coupler 14 as an example, the same effect as in the above embodiment can also be obtained using a high frequency tuning circuit as shown in FIG. 3, an attenuator constructed of resistors as shown in FIG. 4, etc. I can,
In short, anything can be used as long as it can be equivalently represented by a four-terminal network.

Although the present invention is applied to a transponder antenna sharing circuit above, the present invention is not limited to this.
It can be used in all circuits that selectively shunt signals having different frequencies, and has a wide range of applications.

〔Effect of the invention〕

By configuring the invention as described above, the present invention can be connected in series with an equivalent four-terminal network, such as a cavity resonator or a parallel two-wire coupler, without using a coaxial cable that requires a precise length. A shared antenna circuit can be realized with a resonant circuit. Therefore, the trial and error work of selecting or replacing a coaxial cable as appropriate from a large number of coaxial cables, as in the past, is eliminated, and work efficiency can be improved. moreover,
The length of the transmission line of the antenna common circuit can be determined simply by considering the layout, so it can be shortened and transmission loss can be reduced.

That is, according to the present invention, a device that is easy to manufacture and requires low transmission loss, such as an antenna common circuit or other similar functions, can be provided at low cost.

[Brief explanation of drawings]

Figures 1 to 4 show embodiments of the present invention; Figure 1 is a block diagram of an antenna sharing circuit using a cavity resonator, and Figure 2 is a block diagram of an antenna sharing circuit using a parallel two-wire coupler. FIG. 3 is a block diagram of the antenna common circuit, FIG. 3 is a diagram showing a high frequency tuning circuit, and FIG. 4 is a diagram showing an attenuator. FIG. 5 is a block diagram of a conventional antenna sharing circuit. 1.2 (1-----1----Antenna 2, 3
-----------Transmission line 7.24.25--
・−−−−−−−−Series resonant circuit 8−・−・・−−−−
- one cavity resonator 11, 27------- receiver 12,
2 L-------1 transmitter 13.26-・-・-・-
---Band pass filter 14-----m--
・- Parallel two-line coupler agent Patent attorney Masaru Takayama l Figure % 2 figure ・ Bird 3 figure Beauty 4 figure Bird 5 figure

Claims (3)

[Claims] (1) Connect the output end of an equivalent four-terminal network to the receiver, one input end of the four-terminal network to the transmission line connecting the antenna and the transmitter, and the other input end to the receiving frequency. An antenna shared circuit, characterized in that the antenna is connected to the other input/output end of the transmitter via an equivalent series resonant circuit that resonates. (2) When the equivalent four-terminal network is a resonator that resonates at the reception frequency, the output end of the resonator is connected to the receiver, and one of the input ends of the resonator is connected to the antenna. Claim 1, wherein the antenna is connected to the other input/output end of the transmitter via an equivalent series resonant circuit that resonates at the reception frequency, and the other input end is connected to the transmission line connecting the transmitter.
Antenna sharing circuit described in section. (3) The four-terminal network is a cavity resonant circuit that resonates with the receiving frequency, and its output end is connected to the receiver, one of the input ends of the cavity resonant circuit is connected to the antenna, and the other input end is connected to the receiver. are connected via an equivalent series resonant circuit that resonates at the receiving frequency, and the output end of the transmitter is connected to either one of the input ends of the cavity resonant circuit. Antenna sharing circuit described in Section 2.