JP2003158464A - Low noise amplifier and low noise converter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide low noise amplifiers and a low noise converter which are inexpensive and have little influence of channel selection and a high performance characteristic about an input return loss characteristic and about an intra-band gain flatness characteristic. SOLUTION: Range couplers 11 and 12 respectively convert received right- handed (horizontal) polarization signal and left-handed (vertical) polarization signal into balanced signals, balanced low noise amplifiers 21 and 22 amplify the balanced signals, range couplers 13 and 14 convert respective balanced outputs of the balanced low noise amplifiers 21 and 22 into unbalanced signals, switching low noise amplifiers 113 and 114 amplify the unbalanced signals, either of the switching low noise amplifiers 113 or 114 selectively makes an output, a mixer 117 converts a polarization signal outputted from the either of them into an intermediate frequency signal and outputs the intermediate frequency signal to an IF amplifier 119.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low noise amplifier and a low noise converter using the same, and more particularly to a low noise amplifier and an intermediate frequency signal used in a satellite broadcast receiving system for amplifying a high frequency signal coming from a broadcasting satellite. Low noise converter to convert to

[0002]

2. Description of the Related Art FIG. 13 is a block diagram showing the structure of a conventional satellite broadcast receiving system. In FIG. 13, a 20 GHz band (19.7-) coming from a broadcasting satellite (not shown)
The frequency signal of 20.2 GHz) is received by the antenna 101. The antenna 101 includes a low noise converter 102.
Is installed, the frequency signal of the weak radio wave in the 20 GHz band from the broadcasting satellite is in the 1 GHz band (950 to 1450 M
(Hz) IF signal is frequency-converted and low-noise amplified, and given to the indoor receiver 104 to be connected next.

The indoor receiver 104 includes a DBS tuner 105, an FM demodulator 106, a video / audio circuit 107, and an RF modulator 108. The indoor receiver 104 processes the signal supplied from the coaxial cable 103 by each internal circuit, and the television 109
Give to.

FIG. 14 is a block diagram of the 2-input 1-output type low noise converter shown in FIG. The example shown in FIG. 14 is, for example, a low noise converter for receiving a US Ka band satellite signal, and has an input frequency of 19.7 to 20.2 G.
The incoming signal in the Hz band is perpendicular to the right-handed polarization signal and the left-handed polarization signal or the horizontal polarization signal by the orthogonal polarization separator of the feed horn (not shown) attached to the antenna 101 shown in FIG. After being separated into a polarized signal, it is picked up by the antenna probe and given to the input 1 and the input 2 of the low noise converter 102. Then, each signal is a low noise amplifier (LNA: Low Noise Ampl).
ifier) 111, 112 and low-noise amplified, and then supplied to switching low-noise amplifiers 113, 114.

Switching low noise amplifiers 113 and 114
Outputs by switching between inputs 1 and 2. This switching is performed by a 27 MHz pulse signal superimposed on the DC voltage applied to the power supply & control circuit 115 from the indoor receiver 104 connected to the output side of the low noise converter 102. That is, for example, when the pulse signal is ON, the input 1 is selected, and when it is OFF, the input 2 is selected. Therefore, the two switching low noise amplifiers 11
3, 114 are turned on and off by their respective toggle operations, and either one of the signals of input 1 and input 2 is selected.

Switching low noise amplifiers 113 and 114
The output signal selected in step B has the role of passing the desired frequency band and removing the signal in the image frequency band.
It passes through a PF (Band Pass Filter) 116. After that, the switching low noise amplifiers 113, 1
The output signal selected in 14 is mixed with the local oscillation signal of 18.75 GHz from the local oscillator 118 by the mixer 117, frequency-converted into an intermediate frequency signal of 1 GHz band (950 to 1450 MHz), and appropriate noise characteristics and gain characteristics are obtained. Is given to the intermediate frequency (IF) amplifier 119, and is output from the output terminal 120. Power is supplied to each circuit from the power / control circuit 115.

[0007]

In a multi-input / output type low noise converter such as the 2-input 1-output type shown in FIG.
When the channel is selected from the indoor receiver 104 and the ON / OFF operations of the switching low noise amplifiers 113 and 114 are repeated, the switching low noise amplifier 11
The input and output impedances of 3 and 114 fluctuate, and the load fluctuations are the input impedance of the low noise amplifiers 111 and 112 preceded by this and the return loss value required by the customer, which is -20 dB or less (VSWR voltage standing wave ratio). 1.22
The following) cannot be satisfied. For example, it is empirically known that the circuit of the related art shown in FIG. 14 can realize the input / output return loss of about −10 dB to −15 dB as a standard value.

The input 1 and the input 2 of the low noise converter 102 separate the polarization signals connected to the preceding stage (right-handed polarization signal and left-handed polarization signal, or horizontal polarization signal and vertical polarization signal). The switching low noise amplifier 113, which has an effect on the demultiplexer that acts on the signal) as a load, for example, the signal of the input 1 is applied is turned off, and the input 1
It is conceivable that when the return loss of 1 is deteriorated, the output return loss of the duplexer connected to the selected input 2 is also adversely affected. The same applies to the opposite case.

For the same reason as described above, the gain flatness characteristic in the reception band (19.7 to 20.2 GHz) cannot satisfy 0.25 dBpp or less required by the customer.
For example, in the conventional technique shown in FIG. 14, 0.5 dBpp
It is empirically known that the degree is realized as a standard value. However, the product specification value is 1 dBpp
Is the mainstream.

Therefore, a main object of the present invention is to provide a low noise amplifier and a low noise converter which are low in price, have little influence of channel selection, and have high performance with respect to input return loss characteristics and in-band gain flatness characteristics. Is to provide.

[0011]

SUMMARY OF THE INVENTION The present invention is a low noise amplifier for amplifying a right-handed (horizontal) polarized signal and a left-handed (vertical) polarized signal received, each of which has a balanced input and a balanced output. The first and second balanced low-noise amplifiers for amplifying the right-handed (horizontal) polarized signal and the left-handed (vertical) polarized signal, and the received right-handed (horizontal) polarized signal and left-handed (vertical) polarized signal. ) First and second lunge couplers for converting the polarized signals into balanced signals and supplying the balanced signals to the first and second balanced low-noise amplifiers, respectively.

Another invention is a low noise converter which amplifies the received right-handed (horizontal) polarized signal and left-handed (vertical) polarized signal by a low noise amplifier and selectively outputs the amplified signals. First and second balanced low-noise amplifiers having balanced inputs and balanced outputs for amplifying right-handed (horizontal) polarized signals and left-handed (vertical) polarized signals, and received right-handed (horizontal) polarized signals.
First and second balanced couplers for converting a polarized signal and a left-handed (vertical) polarized signal into balanced signals and giving them to the first and second balanced low-noise amplifiers, and the first and second balanced type Third and fourth lunge couplers for converting each balanced output of the low noise amplifier into an unbalanced signal;
And the first and second switching low noise amplifiers for amplifying the signal from the fourth lunge coupler and selectively outputting from either one, and the bias output from any of the first and second low noise amplifiers. And a frequency conversion circuit for converting a wave signal into an intermediate frequency signal and outputting the intermediate frequency signal.

The first and second switching low noise amplifiers each have a balanced input, and
Fifth and sixth lunge couplers for converting the unbalanced outputs of the third and fourth lunge couplers into a balanced output, and frequency conversion circuits for converting the balanced outputs of the first and second switching low noise amplifiers into an unbalanced output 7th and 8th to give to
And the lunge coupler of.

The first to eighth lunge couplers are
Each of the lines includes a central line formed on a substrate, a plurality of coupling lines formed in parallel on both sides of the central line, and a bridge selectively electrically coupling the plurality of coupling lines. One side of the coupled line side is a balanced input, and the other side of the coupled line side is a balanced output.

Of the plurality of coupled lines, the outermost coupled line is selected to have a length that is approximately half that of the central line, and the other coupled lines are selected to have substantially the same length as the central line. Is characterized by.

Furthermore, a waveguide for deriving a right-handed (horizontal) polarized signal and a left-handed (vertical) polarized signal is included, and the end of the coupled line serving as a balanced input serves as a feeding portion of the waveguide. It is characterized by being done.

The frequency conversion circuit includes a local oscillation circuit that outputs a local oscillation signal, a harmonic signal of the local oscillation signal from the local oscillation circuit, and a bias signal output from any one of the first and second low noise amplifiers. And a mixer circuit for mixing the wave signal and outputting an intermediate frequency signal.

The frequency conversion circuit further includes a local oscillation circuit that outputs a local oscillation signal, a multiplication circuit that multiplies the local oscillation signal from the local oscillation circuit, a local oscillation signal that is multiplied by the multiplication circuit, and the first and the first oscillation signals. And a mixer circuit that mixes the polarized signal output from any one of the two low noise amplifiers and outputs an intermediate frequency signal.

Further, a control circuit for outputting a selection signal in response to an externally applied pulse signal is included, and the first and second switching low noise amplifiers are switched according to the selection signal from the control circuit. To do.

Further, it includes a control circuit for outputting a selection signal according to a value of a control voltage given from the outside, and the first and second switching low noise amplifiers are switched according to the selection signal from the control circuit. Characterize.

[0021]

1 is a block diagram showing a low noise converter according to an embodiment of the present invention. In FIG. 1, in this embodiment, instead of the low noise amplifiers 111 and 112 shown in FIG.
A balanced low noise amplifier 21 to which 1 and 13 are connected, and a balanced low noise amplifier 22 to which the lunge couplers 12 and 14 are connected at the input and output thereof are provided. The balanced low-noise amplifiers 21 and 22 have a balanced input and a balanced output, respectively, and have a characteristic that the input reflection loss is small and the attenuation in the band can be reduced because the input reflection is small.

One input end of each of the input-side lunge couplers 11 and 12 is connected to each of the inputs 1 and 2, and the other input end is terminated by 50Ω terminating resistors R1 and R2. One output terminal of each of the range couplers 11 and 12 is connected to one input terminal of the balanced low noise amplifiers 21 and 22, and the other output terminal is connected to the other input terminals of the balanced low noise amplifiers 21 and 22. It One of the input ends of the output-side lunge couplers 13 and 14 is connected to one of the output ends of the balanced low-noise amplifiers 21 and 22, and the other input end is connected to the balanced low-noise amplifier 2.
1 and 22 are connected to the other output end of the lunge coupler 1
One of the outputs of 3 and 14 is terminated by the terminating resistors R3 and R4, and the other output end is the switching low noise amplifier 113,
It is connected to the input terminal of 114. Other configurations are shown in FIG.
Is the same as.

Also in this embodiment, one of the two switching low noise amplifiers 113 and 114 is turned on and the other is turned off to select either the input 1 signal or the input 2 signal. This control is performed by the output terminal 120.
When the 27 MHz signal superimposed on the DC voltage supplied from the indoor receiver 104 is ON, the switching low noise amplifier 113 on the input 1 side is operated and the switching low noise amplifier 114 on the input 2 side is stopped. Performed by. For this purpose, the power supply & control circuit 11
5 is O of 27MHz given from the indoor receiver
Rectify and smooth N and OFF signals and convert to DC level,
Low noise amplifier 1 for switching DC level ON / OFF signals by comparing with a reference voltage with a comparator
It is given to 13,114.

In this way, the lunge couplers 11, 12, 1
By combining 3 and 14 and the balanced low noise amplifiers 21 and 22 and arranging them in front of the switching low noise amplifiers 113 and 114, the input return loss characteristics of the low noise amplifier seen from the input 1 and the input 2 are significantly increased. The switching low noise amplifiers 113 and 114 are turned on and off.
The effect of load fluctuation due to FF is reduced by the balanced low-noise amplifier 2
It is possible to prevent the deterioration of the input return loss characteristic and the deterioration of the in-band gain flatness of the low noise amplifier because the noises 1 and 22 are difficult to receive.

FIG. 2 shows the lunge coupler shown in FIG.
(A) is a layout diagram of the lunge coupler, and (b) shows a symbol. FIG. 3 is a diagram showing a connection state between the lunge coupler of FIG. 2 and an input waveguide.

As shown in FIG. 2 (a), in the runge coupler 10, a strip-shaped central line 31 is formed by a microstrip having a length of approximately λ / 4 on the front surface of a substrate having a full-surface ground electrode formed on the back surface. The coupling lines 32 and 33 called fingers having substantially the same length are arranged in parallel along both sides thereof, and the coupling lines 34 and 35 having approximately half the length are further arranged outside in parallel. There is. Central railroad 3
1 and one end side of the coupling line 34 are electrically connected,
The connecting portion serves as one input end 1 and the other end of the coupled line 32 serves as the other input end 3.

The central line 31 and the other end of the coupling line 35 are electrically connected to each other, and the connecting portion serves as the other output end 4, and the one end of the coupling line 33 serves as one output end 2. Then, the respective tip portions of the coupled lines 34 and 35 are coupled by the bridge 41, and the coupled lines 32 and 3 are coupled.
One end side of 3 is connected by a bridge 42, and the other end side is connected by a bridge 43.

The lunge coupler 10 shown in FIG. 2A is shown in FIG.
It is represented by the symbol shown in (b). Then, as shown in FIG. 3, the substrate 36 is extended to the substrate opening surface 50 of the input waveguide, and the microstrip line is pulled out from the input end 1 of the lunge coupler 10 to form the feeding portion 37.

Here, as a specific example of the lunge coupler 10, as shown in FIG. 3, a dielectric constant of 2.65 and a substrate thickness of 0.
Each coupled line was formed on a double-sided board having a thickness of 61 mm and a copper foil thickness of 50 μm, and the dimensions of each part were W = 0.37 mm and W1 =
The settings were 1.65 mm, S = 0.22 mm, and L = 4.19 mm.

FIG. 4 shows simulation results of input / output return loss and gain characteristics of the balanced type low noise amplifier using the lunge coupler shown in FIG. In FIG. 4, S2
1 is a gain characteristic, 19.7 GHz to 20.2 GHz
The flatness characteristic of gain within the band of 0.03 dBpp is shown, S11 is the input return loss, and -24d
B is shown below, S22 is an output return loss, and shows below -22 dB.

FIG. 5 is a balanced low noise amplifier 2 shown in FIG.
The simulation results of the input / output return loss and the gain characteristic when the lunge couplers 13 and 14 and the switching low noise amplifiers 113 and 114 are connected to the output sides of 1 and 22 are shown.

In FIG. 5, the flatness of the gain characteristic of S21 is suppressed to 0.15 dBpp. Further, the input return loss of S11 is suppressed to −22.8 dB or less. Furthermore, the output return loss of S22 is 23.2 dB.
The following shows the target input / output return loss-20d.
Below B, the gain flatness of 0.25 dBpp is satisfied.

FIG. 6 is a block diagram showing a low noise converter according to another embodiment of the present invention. This embodiment is a switching low noise amplifier 113, 1 shown in FIG.
Instead of 14, the switching balance type low noise amplifiers 19 and 20 in which the lunge couplers 15 and 17 are connected to the input side and the lunge couplers 16 and 18 are connected to the output side are connected. The inputs 1 and 3 of the lunge coupler 15 are connected to the outputs 2 and 4 of the runge coupler 13 in the preceding stage, and the outputs 2 and 4 thereof are
Are connected to the balanced inputs of the switching balanced low noise amplifier 19, and the inputs 1 and 3 of the lunge coupler 17 are connected to the outputs 2 and 4 of the preceding stage lunge coupler 14, and their outputs 2 and
4 is connected to the balanced input of the switching balanced low noise amplifier 20.

The output side lunge coupler 16 has its inputs 1,
3 is connected to the balanced output of the switching balanced low noise amplifier 19, and the input 1 and 3 of the lunge coupler 18 are connected to the balanced output of the switching balanced low noise amplifier 20.
The output 4 of the lunge coupler 16 is connected to the input of the BPF 116, the output 2 is connected to the terminating resistor R4, the output 4 of the lunge coupler 18 is also connected to the input of the BPF 116, and the terminating resistor R6 is connected to the output 2.

FIG. 7 shows simulation results of input / output return loss and gain characteristics in the embodiment of FIG. In FIG. 7, the flatness of the gain characteristic of S21 is 0.05 dB.
The input return loss of pp and S11 is -26 dB or less, S
The output return loss of 22 is -25 dB or less. In this way, the switching balanced low noise amplifier 19,
By providing 20, the input / output return loss is further improved as compared with FIG.

FIG. 8 is a diagram showing another embodiment of the lunge coupler, and FIG. 8A is a layout diagram of the lunge coupler.
(B) shows a symbol.

The runge coupler shown in FIG. 8 is obtained by increasing the number of coupled lines to 6 fingers to widen the band, in addition to the 4-finger runge coupler shown in FIG. That is, as shown in FIG. 8A, the coupled lines 32, 33, 3 called fingers having substantially the same length along both sides of the central line 31.
4, 35 are arranged in parallel, and further coupled lines 36, 37 having a length of about half are arranged outside in parallel. The central line 31 and one end side of the coupling line 34 are electrically connected, the connecting portion is one input end 1, and the other ends of the coupling lines 32 and 36 are electrically connected,
This connecting portion serves as the other input end 3. Further, the center line 31 and the other end side of the coupling line 35 are electrically connected, the connecting portion is the other output end 4, and one ends of the coupling lines 33 and 37 are electrically connected, The connecting portion is one output terminal 2. This lunge coupler is represented by the symbol shown in FIG.

The respective tip portions of the coupled lines 36 and 37 are coupled by a bridge 41, and the coupled lines 32 and 33 are coupled.
One end side of which is connected by a bridge 42 and the other end side of which is connected by a bridge 43.
One end of the line 31 is coupled by the bridge 44, and the other ends of the line 31 and the coupling line 34 are coupled by the bridge 45.

FIG. 9 is a diagram showing still another embodiment of the lunge coupler, (a) is a layout diagram of the lunge coupler, and (b) shows symbols.

The lunge coupler shown in FIG. 9 has the number of coupling lines increased to 8 fingers to further widen the band. That is, as shown in FIG. 9A, coupling lines 32, 33, 34, 35, 36, 37 called fingers having substantially the same length are arranged in parallel along both sides of the central line 31. Further, coupled lines 38 and 39 having a length of about half are arranged in parallel outside. Central railroad 31
And one end sides of the coupled lines 34 and 38 are electrically connected to each other, and the connected portion is one input end 1 and the coupled line 3
The other ends of 2 and 36 are electrically connected to each other, and this connecting portion serves as the other input end 3. Further, the central line 31 and the other ends of the coupled lines 35 and 39 are electrically connected to each other, and the connected portion is the other output end 4, and the coupled lines 33 and 3 are connected.
One end side of 7 is electrically connected, and the connecting portion is one output end 2. This lunge coupler is shown in Fig. 9.
It is represented by the symbol shown in (b).

The respective tip portions of the coupled lines 38 and 39 are coupled by a bridge 41, and the coupled line 33 is further coupled.
And 36, coupled lines 32 and 33, line 31 and coupled line 3
4, coupling lines 32 and 37 are bridges 42 and 4 respectively
They are connected by 3,44,45.

FIG. 10 is a block diagram of a low noise converter according to still another embodiment of the present invention. In this embodiment, a harmonic mixer 130 is provided instead of the mixer 117 shown in FIG. 1, and the other configuration is the same as the low noise converter of FIG.

In FIG. 10, the local oscillator 118 is shown in FIG.
The local oscillation signal of 9.375 GHz, which is 1/2 of the 18.75 GHz local oscillation frequency shown in (3), is oscillated and given to the harmonic mixer 130. The harmonic mixer 130 doubles the local oscillation signal of 9.375 GHz to 18.75.
The GHz harmonic signal and the high frequency signal from the BPF 116 are mixed to output an intermediate frequency signal.

In this embodiment, the frequency of the local oscillation signal oscillated by the local oscillator 118 can be lowered, so that it is easy to realize.

FIG. 11 is a block diagram of a low noise converter according to still another embodiment of the present invention. In this embodiment, the local oscillator 118 is 9.3 as in FIG.
A local oscillation signal of 75 GHz is oscillated, and the local oscillation signal is multiplied by 18.75 GHz, which is doubled by the multiplication circuit 131, applied to the mixer 117, mixed with a high frequency signal from the BPF 116, and an intermediate frequency signal is output. .

FIG. 12 is a block diagram of a low noise converter according to still another embodiment of the present invention. In the embodiment shown in FIG. 1, from the indoor receiver 104 to the output terminal 12
Although the switching low noise amplifiers 113 and 114 are switched depending on whether the 27 MHz signal superimposed on the DC voltage supplied to 0 is ON or OFF, in this embodiment, the supplied DC voltage is 10 to 10, for example.
Input 14 is selected at 14V and input 2 is selected at 16 to 20V. For this purpose, the power supply & control circuit 115 compares the supplied DC voltage with the reference signal by the comparator, and supplies the selection signals of the inputs 1 and 2 to the switching low noise amplifiers 113 and 114.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[0048]

As described above, according to the present invention, by disposing the lunge couplers at the input and output of the low noise amplifier, the input return loss characteristics seen from the two inputs can be greatly improved.

Moreover, the switching low noise amplifier O
Since the balanced low-noise amplifier is less likely to be affected by the load fluctuation due to N and OFF, deterioration of the input return loss characteristic of the low-noise amplifier and deterioration of the gain flatness within the band can be prevented.

Since the lunge coupler is composed of a microstrip line on the substrate and the bridge is composed of a metal conductor, a high-performance input return can be performed without providing an external component such as a waveguide isolator in front of the input waveguide. Loss characteristics and in-band gain flatness can be obtained, which can be realized at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing a low noise converter according to an embodiment of the present invention.

FIG. 2 is a diagram showing the lunge coupler shown in FIG.

FIG. 3 is a diagram showing a connection state between the lunge coupler of FIG. 2 and an input waveguide.

FIG. 4 is a diagram showing a simulation result of input / output return loss and gain characteristics of a balanced low noise amplifier using the lunge coupler shown in FIG.

FIG. 5 is a diagram showing simulation results of input / output return loss and gain characteristics when the lunge couplers 13 and 14 and the switching low noise amplifiers 113 and 114 are connected to the outputs of the balanced low noise amplifiers 21 and 22 shown in FIG. Is.

FIG. 6 is a block diagram showing a low noise converter according to another embodiment of the present invention.

7 is a diagram showing simulation results of input / output return loss and gain characteristics in the embodiment of FIG.

FIG. 8 is a view showing another embodiment of the lunge coupler.

FIG. 9 is a view showing still another embodiment of the lunge coupler.

FIG. 10 is a block diagram of a low noise converter according to still another embodiment of the present invention.

FIG. 11 is a block diagram of a low noise converter according to still another embodiment of the present invention.

FIG. 12 is a block diagram of a low noise converter according to still another embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration of a conventional satellite broadcast receiving system.

14 is a block diagram of the 2-input 1-output type low noise converter shown in FIG.

[Explanation of Codes] 11-18 Lung coupler, 19, 20 Switching balanced low-noise amplifier, 21, 22 Balanced low-noise amplifier, 31 lines, 32-39 Coupling line, 41-45
Bridge, 113,114 switching low noise amplifier, 115 power supply & control circuit, 116 BPF, 117
Mixer, 118 local oscillator, 119 intermediate frequency amplifier circuit, 120 output terminal, 130 harmonic mixer, 131 multiplication circuit.

Continued front page    F-term (reference) 5C025 AA20 DA04                 5J067 AA01 AA04 CA35 CA64 CA87                       FA20 HA25 HA29 HA32 HA33                       KA00 KA32 KA44 KA68 KS19                       LS01 LS02 QA04 SA13 TA01                       TA03                 5K062 AA09 AB01 AD04 AE05 BA02                       BC10 BE08

Claims (8)

[Claims] 1. A low noise amplifier for amplifying a right-handed (horizontal) polarized signal and a left-handed (vertical) polarized signal received, each of which has a balanced input and a balanced output, First and second balanced low-noise amplifiers for amplifying a polarization signal and a left-handed (vertical) polarization signal, and the received right-handed (horizontal) polarization signal and left-handed (vertical) polarization signal, respectively. A low noise amplifier, comprising: a first and a second lunge coupler for converting the signal into a balanced signal and giving it to the first and second balanced low noise amplifiers. 2. A low noise converter which amplifies a right-handed (horizontal) polarized signal and a left-handed (vertical) polarized signal which are received and selectively outputs the amplified signal, each of which has a balanced input and a balanced output. The first and second balanced low-noise amplifiers for amplifying the right-handed (horizontal) polarized signal and the left-handed (vertical) polarized signal, and the received right-handed (horizontal) polarized signal and left-handed polarized signal First and second lunge couplers for converting (vertical) polarized signals into balanced signals and giving the balanced signals to the first and second balanced low noise amplifiers; and the first and second balanced low noise amplifiers Third and fourth lunge couplers for converting the respective balanced outputs of the first and second lunge couplers into an unbalanced signal, and a first and second amplifier for amplifying and selectively outputting the signals from the third and fourth lunge couplers. Second
And a frequency conversion circuit for converting the polarization signal output from any of the first and second low noise amplifiers into an intermediate frequency signal and outputting the intermediate frequency signal. Low noise converter. 3. The first and second switching low noise amplifiers each have a balanced input, and further include fifth and fifth converters for converting unbalanced outputs of the third and fourth lunge couplers to a balanced output. And a seventh and an eighth lunge coupler for converting the balanced outputs of the first and second switching low noise amplifiers to an unbalanced output and supplying the unbalanced outputs to the frequency conversion circuit. The low noise converter according to claim 2. 4. The first to eighth lunge couplers,
Each includes a central line formed on a substrate, a plurality of coupling lines formed in parallel on both sides of the central line, and a bridge selectively electrically coupling the plurality of coupling lines. The coupled line side on one side of the line is a balanced input, and the coupled line side on the other side is a balanced output.
The low noise converter according to claim 1. 5. Among the plurality of coupling lines, the outermost coupling line is selected to have a length that is substantially half that of the central line, and the other coupling lines are selected to have substantially the same length as the central line. The low noise converter according to claim 4, wherein 6. A waveguide for deriving the right-handed (horizontal) polarized signal and the left-handed (vertical) polarized signal, wherein an end of the coupled line serving as the balanced input is the waveguide. 5. A low noise converter according to claim 4, characterized in that it is connected to the power supply of the tube. 7. The frequency conversion circuit includes a local oscillation circuit that outputs a local oscillation signal, a harmonic signal of the local oscillation signal from the local oscillation circuit, and one of the first and second low noise amplifiers. The low noise converter according to claim 2, further comprising: a mixer circuit that mixes the output polarized signal and outputs the intermediate frequency signal. 8. The frequency conversion circuit includes a local oscillation circuit that outputs a local oscillation signal, a multiplication circuit that multiplies the local oscillation signal from the local oscillation circuit, a local oscillation signal that is multiplied by the multiplication circuit, and the local oscillation signal. The first
3. The low noise converter according to claim 2, further comprising: a mixer circuit that mixes the polarized signal output from any one of the second low noise amplifiers and outputs the intermediate frequency signal.