JPH01133432A - Microwave receiver - Google Patents

Abstract

PURPOSE:To prevent the leakage of local oscillation and image disturbances by bringing the image frequency produced when RF signals are converted into a 1st IF signal nearer to the frequency of a 2nd IF signal obtained by converting the 1st IF signal. CONSTITUTION:RF signals are converted into the 1st IF signal after they are mixed with signals from a local oscillator 13 at a 1st mixer 12 and further converted into the 2nd IF signal after they are mixed with signals from the oscillator 13 at a 2nd mixer 15. Since the 2nd IF frequency and RF frequency used for satellite broadcasting are respectively 0.95-1.45GHz and 22.5-23GHz, the image frequency produced at the mixer 12 coincides with a 2nd IF frequency and, since it is separated from the RF frequency, hardly receives any image disturbance, when the local oscillation frequency and 1st IF frequency are respectively set at 10.775GHz and 11.725-12.225GHz. Moreover, since the local oscillation frequency is separated from the RF frequency, the leakage of the local oscillation can be suppressed easily.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention applies to the 22 GHz band (22 GHz band) distributed for broadcasting satellite service.
The present invention relates to a microwave receiving device using a frequency of 2.5 to 23.0 GH2).

Prior Art Satellite broadcasting using a frequency in the 12 GHz band has already been put into practical use. Satellite broadcasting using frequencies in the 22 GHz band is also being considered in the future.

Microwave receivers for satellite broadcasting in the 12GHz band,
For example, in Europe, the receiving frequency is 11.7~12.
5 GHz, a local frequency of 10.75 GHz, and an 11F frequency of 0.96 to 1.75 GHz are used.

In the microwave receiver for satellite broadcasting in the 22 GHz band, the IF
It is also being considered to set the frequency to a value that does not match or is close to the IF frequency of satellite broadcasting in the 12 GHz band.

FIG. 3 shows the configuration of a conventional microwave receiver for satellite broadcasting in the 22 GHz band. In FIG. 3, 1 is an RF amplifier, 2 is a mixer, 3 is a local oscillator, 4 is an IF amplifier, 6 is an RF input terminal, and 6 is an IF output terminal. Here, in order to match the IF frequency with the IF frequency of 12 GHz band satellite broadcasting, 0.95 to 1.45 GHz is selected. Then, since the receiving frequency is 22.6 to 23 GHz, the local oscillation frequency is selected to be 21.55 GH2.

Problems to be Solved by the Invention In the conventional microwave receiver for satellite broadcasting in the 22 GHz band as described above, the receiving frequency fR and the local frequency fL are not separated by 0.95 GHz l, and the station frequency for the receiving frequency is The ratio of the oscillation frequencies apart (fR-fL)/fR is 0.042, which is very small. Therefore, (1) it becomes difficult to suppress leakage of local oscillator signals from the RF input terminal 6; Also, the reception frequency is the image frequency (here 20.
1 to 20.6 GHz), so ■
It has problems such as being vulnerable to image disturbances and deteriorating the characteristics (conversion loss) of the mixer 2 because the image suppression ratio of the mixer 2 deteriorates. In particular, in a microwave receiving device configured with a microwave concentrator circuit, the no-load Q value of the fill cannot be high, so the filter band can be used to pass an RF multiplied signal, or to block an image signal or local oscillation signal. It was difficult to make the external characteristics steep, and local leakage and image interference were very important problems.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-frequency band microwave receiving apparatus that suppresses local oscillation leakage in a microwave receiving apparatus and is resistant to image interference.

Means for Solving the Problems The present invention provides a first mixer for converting an RF multiplied signal into a first IF multiplied signal, and a second mixer for converting the first IF multiplied signal into a second IF multiplied signal. and an image frequency corresponding to the RF multiplied signal frequency in the first mixer is close to or coincides with the frequency of the second IF signal.

According to the above-described structure, the present invention can separate the local oscillation frequency as well as the image frequency far from the reception frequency, so it is possible to easily create a high frequency band microwave receiving device that is resistant to local oscillation leakage and image interference. realizable.

Embodiment FIG. 1 shows a first embodiment of a microwave receiving apparatus according to the present invention.

In FIG. 1, 11 is an RF amplifier, 12 is a first mixer, 13 is a local oscillator, 14 is an 11F amplifier, 15 is a second mixer, 16 is a second IF amplifier, 17 is an RF input terminal, 18 is an IF output terminal. Here, set the second IF frequency to 0.96 to 1.45 GH so that it matches the IF frequency of the microwave receiver for 12 GHz band satellite broadcasting.
I have selected z. Then, the reception frequency is 22.6~2
Since it is 3GHz, the local frequency is 10,7745GH
z, 11th F frequency is 11.725~12.225G
Hz, the image frequency of the first mixer 12 is 0.95
~1.45GHz.

The image frequency of the second mixer 16 is 9.325~e,
a2tsGHz.

In the embodiment shown in FIG. 1 above, the image frequency of the first mixer 12 is 0.95 to 1.45 GHz, which is the same as the 21st F frequency, and is completely different from the receiving frequency of 22.5 to 2-3 GHz. This simplifies the configuration of the image signal blocking filter, and makes it possible to configure a receiving device that is extremely resistant to image interference.

At the same time, since the image processing of the first mixer 12 becomes easier, the conversion loss characteristics of the first mixer 12 can be improved.

■Local frequency 10.775GHz compared to receiving frequency
Since they are separated by a large distance, the configuration of the local oscillator signal blocking filter is easy), and it becomes easy to suppress local oscillator leakage from the RF input terminal 17.

■ 11th F amplifier 14, second mixer 15, second IF
The configuration and frequency relationship of the amplifier 16 and local oscillator 13 are similar to those of the 12 GHz band microwave receiver for satellite broadcasting, so many of the circuits used in the 12 GHz band microwave receiver for satellite broadcasting can be used for 22 GHz band satellite broadcasting. It can be used in microwave receiving equipment, and its practical effects are extremely large.

For example, if a waveguide WR42 corresponding to the receiving frequency is used as the RF input terminal 17, the cutoff frequency of this waveguide is approximately 14 GHz. By simply using the waveguide as a tube, this waveguide acts both as an image signal blocking filter and as a local oscillation signal blocking filter, making it possible to construct a receiving device that is resistant to image interference and has little local oscillation leakage.

FIG. 2 shows a second embodiment of the microwave receiving apparatus according to the present invention, and the same parts as in FIG. 1 are given the same numbers and will be described. In FIG. 2, 11 is an RF amplifier, 12 is a first
19 is a first local oscillator, 14 is an 11F amplifier, 16 is a second mixer, 20 is a second local oscillator,
16 is the second IF amplifier, 17 is the RF input terminal, and 18 is the I
This is the F output terminal. Reception frequency (22.5~23GHz
) is converted by the first mixer 12 to a frequency (11,-r ~ 12.2 GHz) that matches the receiving frequency (11,7 ~ 12.2 GHz) of 12 GHz band satellite broadcasting, and then converted by the second mixer 12. 15, the IF frequency (0.95 to 1.4
5GHz) matching frequency (0,95~1.45GHZ)
z).

In the embodiment shown in FIG. 2 above, (1) the image frequency of the first mixer 12 is 0.9 to 1.4 GHz, which is close to the second IF frequency, and is completely distant from the receiving frequency of 22.5 to 23 GHz; The configuration of the image signal blocking filter is simplified, and a receiving device that is extremely resistant to image interference can be configured. At the same time, since the image processing of the first mixer 12 becomes easier, the conversion loss characteristics of the first mixer 12 can be improved.

■ The local oscillator frequencies of the first local oscillator 19 and the second local oscillator 20 are both 10 GHz relative to the reception frequency.
Since it is far away from the band, it becomes easy to configure a local oscillator signal blocking filter, and it becomes easy to suppress local oscillator leakage from the RF input terminal 17.

■ 11th F amplifier 14, second mixer 15, second IF
The configuration and frequency relationship of the amplifier 1e and the second local oscillator 2o are the same as those of the 12 GHz band microwave receiver for satellite broadcasting, so many of the circuits used in the 12 GHz band microwave receiver for satellite broadcasting are compatible with the 22 GHz band microwave receiver. It can be used in microwave receivers for satellite broadcasting, and its practical effects are extremely large.

For example, if a waveguide WR42 corresponding to the receiving frequency is used as the RF input terminal 17, the cutoff frequency of this waveguide is approximately 14 GHz. By simply using the waveguide as a tube, the waveguide acts both as an image signal blocking filter and as a local oscillation signal blocking filter, making it possible to configure a microwave receiving device that is resistant to image interference and has little local oscillation leakage.

Note that in the embodiments shown in FIGS. 1 and 2 above, the RF amplifier 11 and the 11th F amplifier 14 are used in the configuration circuit of the microwave receiving device, but these amplifiers are not necessarily necessary for the microwave receiving device. Instead, one or both of these two amplifiers 11.14 may be missing.

Furthermore, the 11th F frequency and the 2nd IF frequency are 12GH
Reception frequency and IF of microwave receiver for Z-band satellite broadcasting
Set the frequency to match or be close to the first one.
In the example shown in the figure, 11,725~12,225GHz
and 0.95-1.45 GHz, and in the example of FIG. 2, 11.7-12.2 GHz and 0.95-
Although 1.45 GHz is used, it is not necessarily necessary to use these frequencies.
GHz) and IF frequency (0.95~1.75GHz
), partially overlap, or be close to the
It is sufficient if it is used in a microwave receiving device for Z-band satellite broadcasting.

Effect of the invention As described above, the present invention has the following effects.

(1) Since the interval between the image frequency and the receiving frequency can be widened, a receiving device that is resistant to image interference can be constructed.

(2) Since the interval between the image frequency and the reception frequency can be widened, the image signal generated by the first mixer can be subjected to image recovery processing, thereby preventing deterioration of the conversion loss characteristics of the first mixer. In particular, this image recovery processing is an effective means when the first mixer is a single-end type that can be configured with one mixer diode.

(3) Since the interval between the local oscillation frequency and the reception frequency can be widened, it becomes easy to suppress local oscillation leakage from the RF input terminal. In particular, even if you just use a waveguide as the RF input terminal,
Local leakage can be suppressed by utilizing the high-pass fill characteristics of the waveguide.

(4) The configuration and frequency relationship of the 11th F amplifier, second mixer, second IF amplifier, and local oscillator are 12GH
Since it is almost the same as the Z-band microwave receiver for satellite broadcasting, many of the circuits used in the 12GHz-band microwave receiver for satellite broadcasting can be used in the 22GHz-band microwave receiver for satellite broadcasting. can be used rationally and cost can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a microwave receiving device according to a first embodiment of the present invention, FIG. 2 is a block diagram of a microwave receiving device according to a second embodiment of the present invention, and FIG. 3 is a block diagram of a microwave receiving device according to a second embodiment of the present invention. FIG. 2 is a block diagram of a receiving device. 11...RF amplifier, 12...First mixer, 13.19.20...Local oscillator, 1
4...11th amplifier, 15...2nd
mixer, 16... second IF amplifier, 17...
...RF input terminal, 18...IF output terminal. Name of agent: Patent attorney Toshio Nakao and 1 other person! −
1 [Summer Lda) 1 Figure 2 Figure 3 21.556H1 Bureau Ryo 1t1 Takama

Claims (4)

[Claims] (1) A first mixer that converts an RF signal into a first IF signal; and a second mixer that converts the first IF signal into a second IF signal; A microwave receiving device characterized in that an image frequency corresponding to the frequency of the RF signal in the mixer is close to or coincides with the frequency of the second IF signal. (2) The microwave receiving device according to claim 1, wherein the frequency of the RF signal is in the 22 GHz band, and the frequency of the first IF signal is around 12 GHz. (3) The microwave receiving device according to claim 1, characterized in that a waveguide is used as an input line for the RF signal. (4) The microwave receiving device according to claim 1, wherein the local oscillator of the first mixer and the local oscillator of the second mixer oscillate at the same frequency.