KR100573013B1 - Radar system using balance topology - Google Patents

Abstract

The present invention relates to a radar system using a balanced structure, which uses a balanced structure to cancel the leakage signals of the transmitting end to each other to increase the reception sensitivity, as well as to prevent the receiver from being saturated by the large leakage signal of the transmitting end and the receiving end. It is possible to obtain the ultra-small and high sensitivity of the radar system by preventing the noise figure from rising due to leakage power and sharing the transmit / receive antenna.

Radar, Balanced Structure, Leakage Signal, Ultra Small, High Sensitivity, Adaptive Radar, Reception Sensitivity

Description

Radar system using balance structure {RADAR SYSTEM USING BALANCE TOPOLOGY}             

1 is a circuit diagram showing a general radar system, (A) is a structure in which the transmitting and receiving antennas are shared, and (B) is a structure in which the transmitting and receiving antennas are separated.

2 is a circuit diagram schematically showing a radar system using a balance structure according to the present invention.

3 is a circuit diagram illustrating in detail a radar system using a balance structure according to the present invention.

4 is a graph showing the degree of leakage signal attenuation according to the mismatch of magnitude and phase between leakage signals in a radar system using a balance structure.

5 is a circuit diagram schematically illustrating another embodiment capable of correcting a mismatch of a balance signal in a radar system using a balance structure according to the present invention.

   -Explanation of symbols for the main parts of the drawings-

101: oscillator 102: power divider

103 power amplifier 104 antenna

105: low noise amplifier 106: mixer

107 filter 201 circulator

202: terminating resistor 301: balanced signal generator

302a: first coupler block 302b: second coupler block

303: power synthesizer 401: variable impedance

402: DSP ctrl: control signal

Rx: Receive Signal Tx: Transmit Signal

The present invention relates to a radar system using a balanced structure, and more particularly, by using a balanced structure to cancel the leakage signals of the transmitting end to each other to increase the reception sensitivity and to prevent the receiver from being saturated by the large leakage signal of the transmitting end. The present invention relates to a radar system using a balanced structure that prevents the receiving end from increasing the noise figure due to the leakage power of the transmitting end and shares the transmitting and receiving antennas so that the ultra-compact and high sensitivity characteristics of the radar system can be simultaneously obtained.

1 is a circuit diagram showing a general radar system, (A) is a structure in which the transmitting and receiving antennas are shared, and (B) is a structure in which the transmitting and receiving antennas are separated.

First, in the case of a radar system having a structure in which the transmit and receive antennas shown in FIG. 1A are shared, there is an advantage that the size of the entire system can be reduced because only one antenna 104 is used, but a circulator Since the isolation of transmission and reception of the power divider 102 is low at a very high frequency, a signal of a transmitting end having a high output power flows into the receiving end so that the reception sensitivity of the radar system is reduced, resulting in a weak reception signal. Makes it difficult to detect.

In addition, the low noise amplifier 105 or the mixer 106 constituting the receiving end is saturated to deteriorate the characteristics of the entire radar system.

In addition, the noise figure of the receiver becomes worse due to a large leakage signal of the transmitter.

In order to solve this problem, in the case of a high-power radar system, as shown in FIG.

As described above, when the transmitting antenna 104 and the receiving antenna 104 are separated, the isolation between the transmitting end and the receiving end is better than that of the case of using the circulator (not shown), the Lange coupler 201, or the power divider 102. The reception sensitivity is improved and the saturation of the receiver can be prevented, but the use of two antennas 104 increases the size of the radar system. Since the antenna 104 occupies the largest area in the radar system, This is a problem that makes implementation difficult.

In order to increase the isolation between the transmitting end and the receiving end while sharing the transmitting and receiving antennas for the miniaturization of the radar system, the conventionally proposed invention has the same magnitude as the transmitted signal leaked to the receiving end by using a vector modulator and is 180 degrees out of phase. I have further described a structure in which the signal is added to the receiving end through a coupler and added to the leakage signal of the transmitting end to cancel each other, so as to be disclosed in US Pat. No. 4,970,519 "Continuously Transmitting and Receiving Radar".

In this structure, when the frequency is increased, it becomes difficult to manufacture a high frequency vector modulator, so that it is difficult to make an accurate offset signal, and it is difficult to obtain high isolation at high frequencies, and it is complicated because there are many parts for manufacturing a radar system. There was a problem that the price is rising.

The present invention has been made to solve the above problems, and an object of the present invention is to cancel the leakage signals of the transmitter by using a balanced structure to increase the reception sensitivity as well as the receiver to be saturated by the large leakage signal of the transmitter. The present invention provides a radar system using a balanced structure that can prevent the receiver from increasing the noise figure due to leakage power of the transmitter and share the transmit / receive antenna so that the ultra small and high sensitivity of the radar system can be simultaneously obtained.

In addition, an object of the present invention is to provide a radar system that can achieve a higher transmit and receive isolation by correcting the mismatch of the balance signal using a DSP (Digital Signal Processor) when manufacturing a balanced structure.

A radar system according to an embodiment of the present invention for realizing the above object comprises: a balance signal generator for generating a balance signal having a phase difference of 180 °; A first coupler block comprising one of a four-port coupler such as a directional coupler and a Lange coupler and a power divider or a circulator, and radiating one of the balance signals generated by the balance signal generator through an antenna; A second coupler block comprising one of a four-port coupler such as a directional coupler and a Lange coupler and a power divider or a circulator, and terminating one of the balance signals generated by the balance signal generator with a terminating resistor to ground; ; A power synthesizer for synthesizing the received signal inputted through the antenna and the transmitted signal leaked from the first to second coupler blocks to the receiving end; A low noise amplification of the output signal of the power synthesis unit, and mixing and filtering the signal of the balance signal generator, characterized in that consisting of a receiving end for outputting a baseband signal.

A radar system according to another embodiment of the present invention for achieving the above object comprises: a balance signal generator for generating a balance signal having a phase difference of 180 °; A first coupler block comprising one of a four-port coupler such as a directional coupler and a Lange coupler and a power divider or a circulator, and radiating one of the balance signals generated by the balance signal generator through an antenna; A second coupler block comprising one of a four-port coupler such as a directional coupler and a Lange coupler and a power divider or a circulator to terminate one of the balanced signals generated by the balanced signal generator with variable impedance to ground; ; A power synthesizer for synthesizing the received signal inputted through the antenna and the transmitted signal leaked from the first to second coupler blocks to the receiving end; A receiver for low noise amplifying the output signal of the power synthesizer, mixing and filtering the signal of the balance signal generator, and outputting the baseband signal as a baseband signal; And a DSP for monitoring the DC offset signal from the mixed signal at the receiving end to adjust the variable impedance by an external control signal.

In the present invention, the balance signal generator is characterized by consisting of any one of a structure for generating a balance signal using an oscillator and a balun (Balun) to generate a balance signal itself in an oscillator such as a differentially coupled oscillator, a balance oscillator.

delete

In the present invention, the terminating resistor is characterized by having the same impedance as the antenna.

In the present invention, the power synthesizer is characterized in that it is any one of a three-port synthesizer such as a Wilkinson combiner and a T-junction combiner.

According to the present invention, one of the balance signals having a 180 ° phase difference generated by the balance signal generator is applied to the antenna and radiated, and the other signal whose phase is opposite to that of the signal is terminated in the termination resistance or the variable impedance. The transmitted signal leaked from the second coupler block to the receiving end is canceled when added to the power synthesizer due to the phase difference of 180 ° so that only the received signal received through the antenna is amplified by the low noise amplifier at the receiving end and passed through the mixer. It is converted into a baseband signal and output.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. This embodiment is not intended to limit the scope of the present invention, but is presented by way of example only and the same parts as the conventional configuration using the same reference numerals and names.

2 and 3 are circuit configuration diagrams showing a radar system using a balance structure according to the present invention.

As shown here, a balance signal generator 301 for generating a balance signal having a phase difference of 180 °, and a first coupler for radiating one of the balance signals generated by the balance signal generator 301 through the antenna 104. A block 302a, a second coupler block 302b for terminating the other signal of the balance signal generated by the balance signal generator 301 with the terminating resistor 202 at ground, and receiving received via the antenna 104 The power combining unit 303 for synthesizing the signal Rx and the transmission signal Tx leaked from the first to second coupler blocks 302a and 302b to the receiving end and the output signal of the power combining unit 303 with low noise Low noise amplification through the amplifier 105 is mixed with the signal of the balance signal generator 301 and the mixer 106 is composed of a receiving end for outputting a baseband signal through the filter 107 (baseband signal).

At this time, since the balance signal generator 301 should use a balance signal having the same magnitude and 180 ° out of phase with each other as an output signal of the transmitter, an oscillator capable of generating a balanced output itself, for example, a differential mutual coupling oscillator Differential Cross-Coupled Oscillator or Balanced Oscillator may be used, and in the case of a single-ended oscillator, a balanced signal may be generated by using a balun.

Also, the first to second coupler blocks 302a and 302b may include a 4-port coupler such as a directional coupler, a Lange coupler, and a power divider as shown in FIG. 3. It may be configured as a divider or a circulator 201.

The power synthesizer 303 may be a three-port synthesizer such as a Wilkinson Power Combiner and a T-Junction combiner.

The operation of the radar system thus constructed is as follows.

That is, the balance signal generator 301 generates a balance signal having the same size and a phase difference of 180 °, and outputs a transmission signal Tx amplified by a balance power amplifier (not shown) for high output.

The amplified transmission signal Tx is input to a Lange coupler of the first to second coupler blocks 302a and 302b, respectively. At this time, the first coupler block 302a is connected to the antenna 104 so that the balance signal is radiated through the antenna 104 and the signal reflected from the target object is again input through the antenna 104. The second coupler block 302b is terminated to the ground by a termination resistor 202 having the same impedance as that of the antenna 104 so that the balance signal is not radiated.

However, due to isolation characteristics of the Lange coupler of the first to second coupler blocks 302a and 302b, the transmission signal Tx is attenuated to some extent, but because the isolation is low, the large transmission signal Tx leaks to the receiver. Will flow into the. Since the transmission signals Tx leaked to the receiver are the same in magnitude and 180 ° out of phase, they are canceled when added by a Wilkinson Power Combiner or T-Junction Combiner. Only the reception signal Rx remains.

Accordingly, the signal input to the receiving end is eliminated the transmission signal Tx leaked from the transmitting end and only the receiving signal Rx reflected from the target object remains, which is amplified by the low noise amplifier 105 of the receiving end and the mixer 106. The baseband signal is converted into a baseband signal through the filter 107 and output through the filter 107.

4 is a graph showing the degree of leakage signal attenuation according to the mismatch of magnitude and phase between leakage signals in a balanced structure.

As shown here, the smaller the difference between the phase and magnitude of the two leakage signal powers, the more isolation there is. Therefore, this mismatch can be reduced when manufactured in the form of MMIC (Microwave Monolithic Integrated Circuit). However, when fabricating in a hybrid form, there is a problem that isolation characteristics may deteriorate because a lot of mismatches may occur.

In particular, since different components are connected to the part where the antenna is connected and the part terminated by the terminating resistor, a large number of mismatches may occur, so as to correct this, instead of the terminating resistor 202 as shown in FIG. 5. The variable impedance 401 is connected to the DSP, and a mismatch of elements or other combinations is monitored by a DC control signal (Ctrl) by an external control signal (Ctrl) by monitoring a DC offset signal output from the mixer 106. The variable impedance 401 may be varied using a processor 402 to correct mismatch components to match the same impedance as the antenna 104.

As described above, the present invention not only improves the reception sensitivity by canceling the leakage signals of the transmitting end with each other using a balanced structure, but also prevents the receiver from being saturated by the large leakage signal of the transmitting end and makes the receiving end noisy due to the leakage power of the transmitting end. It is possible to share the transmit and receive antennas without preventing the exponent from increasing, so that the ultra-small and high sensitivity of the radar system can be simultaneously obtained.

Claims (6)

A balance signal generator for generating a balance signal having a phase difference of 180 °; A first coupler block comprising one of a four-port coupler such as a directional coupler and a Lange coupler and a power divider or a circulator, and radiating one of the balance signals generated by the balance signal generator through an antenna; A second coupler block comprising one of a four-port coupler such as a directional coupler and a Lange coupler and a power divider or a circulator, and terminating one of the balance signals generated by the balance signal generator with a terminating resistor to ground; ; A power synthesizer for synthesizing the received signal inputted through the antenna and the transmitted signal leaked from the first to second coupler blocks to the receiving end; A receiver for low-noise amplifying the output signal of the power synthesizer, mixing and filtering the signal of the balance signal generator and outputting it as a baseband signal. Radar system using a balanced structure, characterized in that consisting of. A balance signal generator for generating a balance signal having a phase difference of 180 °; A first coupler block comprising one of a four-port coupler such as a directional coupler and a Lange coupler and a power divider or a circulator, and radiating one of the balance signals generated by the balance signal generator through an antenna; A second coupler block comprising one of a four-port coupler such as a directional coupler and a Lange coupler and a power divider or a circulator to terminate one of the balanced signals generated by the balanced signal generator with variable impedance to ground; ; A power synthesizer for synthesizing the received signal inputted through the antenna and the transmitted signal leaked from the first to second coupler blocks to the receiving end; A receiver for low noise amplifying the output signal of the power synthesizer, mixing and filtering the signal of the balance signal generator, and outputting the baseband signal as a baseband signal; DSP that monitors the DC offset signal from the mixed signal at the receiving end and adjusts the variable impedance by an external control signal Radar system using a balanced structure, characterized in that consisting of. The balance signal generator according to claim 1 or 2, wherein the balance signal generator is any one of a structure that generates a balance signal by using an oscillator and a balun that generate a balance signal in an oscillator such as a differentially coupled oscillator or a balance oscillator. Radar system using a balance structure, characterized in that made. delete The radar system using a balance structure of claim 1, wherein the termination resistor has the same impedance as the antenna. 3. The radar system according to claim 1 or 2, wherein the power synthesizer is one of a three-port synthesizer such as a Wilkinson combiner and a T-junction combiner.

Images