JP2000286745A - Common antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a common antenna system with not a large size that can prevent a sneak path of a transmission signal to a receiver side without the use of a filter with high Q. SOLUTION: An antenna of the common antenna system 1 is used in common for transmission and reception but part of a transmission signal passing through a reception band filter is added to a received signal as an intrusion signal. The antenna of the common antenna system 1 is provided with an intrusion prevention means 10 consisting of a 1st directional coupler 11 that extracts part of the transmission signal given to a transmission band filter, a delay device 12 that delays the extracted transmission signal, a phase shifter 13 that adjusts the phase of the delayed transmission signal, an attenuator 14 that adjusts the amplitude of the transmission signal whose phase is adjusted, and a 2nd directional coupler 15 that applies the attenuated transmission signal to the output of the reception band filter as an intrusion elimination signal. The intrusion elimination signal has the same delay as, the same amplitude as and the opposite phase to those of the intruded signal and cancels the intruded signal in the received signal, thus eliminating the intruded signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting apparatus for transmitting a transmission signal from an antenna via a transmission band filter so that a reception signal received by the antenna is selectively extracted via a reception band filter. The present invention relates to a common antenna device used in common for reception and reception, in which a part of the transmission signal passes through a reception band filter and is added to the reception signal as a mixed signal.

[0002]

2. Description of the Related Art Conventionally, a common antenna device 2 of this kind is configured as shown in FIG. That is, the transmission signal SD is transmitted from the antenna 20 via the transmission band filter 21, and the reception signal RV is received by the same antenna 20 and is taken in via the reception band filter 22. Since the transmission signal SD and the reception signal RV have different frequencies, the frequencies passed by the transmission band filter 21 and the reception band filter 22 are also different. If the two frequencies are far apart, the transmission signal SD It hardly mixes into the signal RV.

[0003]

In the above-mentioned common antenna apparatus, when the frequency of the transmission signal SD and the frequency of the reception signal RV are largely apart, the transmission signal SD is not transmitted to the reception signal RV.
When the two frequencies are close to each other, the transmission signal SD is radiated from the antenna 20 via the path P0, but a part passes through the reception band filter 22 via the path P2. However, the signal RV passes through the reception band filter 22 together with the reception signal RV from the antenna 20, so that the transmission signal SD interferes with the reception signal. In order to prevent the transmission signal SD from sneaking into the reception side, the filter (particularly, the reception band filter 22) must have a high Q value, which is inevitably large.
There is a problem that insertion loss also increases.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a common antenna apparatus which can prevent a transmission signal from sneaking into a receiving side without using a filter having a high Q value and which is not large in size.

[0005]

According to the present invention, a transmission signal is output from an antenna via a transmission band filter, and a reception signal received by the antenna is received via a reception band filter. In the common antenna device, the antenna is used commonly for transmission and reception so that a part of the transmission signal passes through a reception band filter and is added to the reception signal as a mixed signal. A mixing prevention unit that extracts a part of the signal, generates a mixed removal signal having the same delay, the same amplitude, and the opposite phase as the mixed signal, adds the mixed signal to the reception signal passed through the reception band filter, and cancels and removes the mixed signal. Have.

Further, in the present invention, the mixing preventing means includes a first directional coupler for extracting a part of a transmission signal input to a transmission bandpass filter, and a transmission unit extracted by the first directional coupler. A delay unit for delaying the signal, a phase shifter for adjusting the phase of the delayed transmission signal, an attenuator for adjusting the amplitude of the phase-adjusted transmission signal, and receiving the transmission signal passing therethrough And a second directional coupler for adding to the received signal passed through the band filter.

In the embodiment of the present invention, the transmission signal SD is output from the antenna 20 via the transmission band filter 21, and the reception signal RV received by the antenna 20 is selectively extracted via the reception band filter 22. In order to make the antenna 2
0 is commonly used for transmission and reception, but the transmission signal S
Part of the signal D passes through the reception band filter 22 and the received signal RV
In the common antenna device which is added as a mixed signal to the received signal, a part of the transmission signal SD is extracted, a mixed signal having the same delay, the same amplitude, and the opposite phase as the mixed signal is generated, In addition to the signal RV, a mixing prevention unit 10 for canceling and removing the mixing signal is provided. in this case,
The mixing prevention means 10 includes a first directional coupler 1 that extracts a part of the transmission signal SD input to the transmission bandpass filter 21.
1, a delay unit 12 for delaying the transmission signal extracted by the first directional coupler, a phase shifter 13 for adjusting the phase of the delayed transmission signal, and an amplitude of the phase-adjusted transmission signal. And an attenuator 14 for adjusting the transmission signal passing therethrough and adding the transmission signal passing therethrough to the reception signal passing the reception band filter 22.
Directional coupler 15.

[0008] According to such a configuration, the mixing preventing means adds the mixed signal, which is the same signal as the transmitted signal component mixed in the received signal but has the opposite phase, to the received signal. The transmission signal component mixed in the signal is canceled by the mixing removal signal, and a reception signal in which the transmission signal component is suppressed is obtained.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing an example of a common antenna device according to the present invention.
A common antenna device 1 shown in FIG. 1 includes an antenna 20, a transmission band filter 21, and a reception band filter 2 which are conventionally provided.
In addition to the above, a mixing preventing means 10 is provided between the input terminal of the transmission band filter 21 and the output terminal of the reception band filter 22. The transmission signal SD (for example, microwave) passes through the transmission band filter 21 and the path P0 and is radiated into the air from the antenna 20. A part of the transmission signal SD is transmitted through the path P1.
And a mixed signal that passes through the receiving band filter 22 and is mixed into the received signal. The mixing preventing means 10 generates, from the transmission signal, a mixing removal signal having the same delay, the same amplitude, and the opposite phase as the mixing signal passed through the reception band filter 22, and adds the mixed signal to the reception signal RV passed through the reception band filter 22. Offset.

The mixing preventing means 10 includes a first directional coupler 11 for extracting a part (AdB) of a transmission signal input to a transmission bandpass filter, and a transmission section extracted by the first directional coupler 11. A delay unit 12 for delaying the signal, a phase shifter 13 for adjusting the phase of the delayed transmission signal, an attenuator 14 for adjusting the amplitude of the phase-adjusted transmission signal, and a transmission signal passing therethrough Is combined with the reception signal passed through the reception band filter 22 as a mixed removal signal (coupling amount Bd
B) and a second directional coupler 15 to be used. The coupling amounts A and B by the first and second directional couplers 11 and 15 and the phase shifter so that the component of the transmission signal included in the reception signal passing through the second directional coupler 15 is minimized. 1
3 and the amount of attenuation by the attenuator 14 are adjusted.

As a result of the above-mentioned adjustment, if the amplitude deviation and the phase deviation between the transmission signal component from the path P1 and the phase signal component from the path P2 are d and θ, respectively (the delay amount is determined by the difference The suppression amount K of the transmission signal component is given by the following equation (1): K = 10 log (1 + 10 ^{d /} 10−2 × 10 ^{d / 20} × COS θ) (1) expressed. Therefore, if the amplitude deviation d and the phase deviation θ are reduced, the suppression amount K can be increased, and the amount of the transmission signal wrapping around the reception signal can be reduced. It is not necessary to increase the Q value of the filters 21 and 22 in accordance with the reduction of the wraparound, and the filters 21 and 22 can be reduced in size and loss. As is clear from the comparison between FIGS. 1 and 2, it is easy to replace the conventional common antenna device 2 with the common antenna device 1 of the present invention by adding the mixing preventing means 10.

[0012]

As described in detail above, in the common antenna device, the transmission signal is output from the antenna via the transmission band filter, and the reception signal received by the antenna is selectively extracted via the reception band filter. For this reason, the antenna is commonly used for transmission and reception, but a part of the transmission signal passes through a reception band filter and is added to the reception signal as a mixed signal. Therefore, in the common antenna apparatus of the present invention, the mixing preventing means extracts a part of the transmission signal, generates a mixing removal signal having the same delay, the same amplitude, and the opposite phase as the mixing signal, and The mixed signal is canceled out in addition to the received signal that has passed. As a result, the transmission signal component mixed in the reception signal is canceled by the mixing removal signal, and a reception signal in which the transmission signal component is suppressed is obtained. Therefore, in response to the suppression of the transmission signal component, it is possible to prevent the transmission signal from sneaking into the receiving side without using a filter having a high Q value, and it is possible to provide a common antenna apparatus that is not large in size. .

Further, in the present invention, the mixing preventing means includes: a first directional coupler for extracting a part of a transmission signal input to a transmission bandpass filter; A delay unit for delaying the signal, a phase shifter for adjusting the phase of the delayed transmission signal, an attenuator for adjusting the amplitude of the phase-adjusted transmission signal, and receiving the transmission signal passing therethrough With the configuration including the second directional coupler for adding the reception signal passed through the band-pass filter, the conventional common antenna device can be easily replaced with the common antenna device of the present invention.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a common antenna device according to the present invention.

FIG. 2 is a block diagram showing a conventional example of a common antenna device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 common antenna device 10 mixing prevention means 11 first directional coupler 12 delay device 13 phase shifter 14 attenuator 15 second directional coupler 20 antenna 21 transmission band filter 22 reception band filter

Claims (2)

[Claims] A transmission signal is output from an antenna via a transmission band filter, and a reception signal received by the antenna is selected and extracted via a reception band filter so that the antenna is common to transmission and reception. In a common antenna device in which a part of the transmission signal passes through a reception band filter and is added to the reception signal as a mixed signal, a part of the transmission signal is extracted, and the same delay and the same amplitude as the mixed signal are extracted. A common antenna apparatus comprising: a mixing preventing unit that generates a mixing removal signal having an opposite phase, and cancels and removes the mixing signal in addition to the reception signal that has passed through the reception band filter. 2. The mixing device according to claim 1, wherein the first directional coupler extracts a part of the transmission signal input to the transmission bandpass filter, and delays the transmission signal extracted by the first directional coupler. A delay unit that gives a delay, a phase shifter that adjusts the phase of the delayed transmission signal, an attenuator that adjusts the amplitude of the phase-adjusted transmission signal, and a transmission signal that passes through the reception band filter. The common antenna apparatus according to claim 1, further comprising a second directional coupler for adding the received signal to the received signal.