KR100748992B1 - Circularly polarized radar apparatus - Google Patents

Abstract

A circularly polarized radar device is provided to prevent the waste of power by decreasing the loss of transmitted power and polarization loss, and to make the size small by reducing the influence of interference although two radar devices face each other. A circularly polarized radar device for obtaining a baseband signal by removing a transmitted leak signal without the loss of transmitted power is composed of a signal generator(301) generating two signals with phase difference of 180 degrees; first and second coupler blocks(302a,302b) receiving and transmitting two signals generated from the signal generator, to an antenna(403) and a mixer(106); the circularly polarized antenna receiving the signals from the first and second coupler blocks; a 90 degree-phase delay lag block(404) connected between the second coupler block and the input side of the antenna; a power combination unit(303) combining received signals input through the antenna and removing the received signal leaking from the first and second coupler blocks to a receiving stage; and the mixer receiving the signals from the first and second coupler blocks and mixing LO signals output from the first and second coupler blocks and a signal output from the power combination unit.

Description

Circularly Polarized Radar Apparatus

1A and 1B are block diagrams schematically showing a linearly polarized radar device having a balanced structure according to the prior art;

2 is a block diagram schematically showing a radar device according to an embodiment of the present invention;

3 is a view showing a specific configuration example of the radar device of FIG. And

FIG. 4 is a block diagram illustrating a case where a three-port device such as a circulator is used as the coupler block in the radar device of FIG. 2.

Explanation of symbols on the main parts of the drawings

105: low noise amplifier

106: mixer

107: filter

301: signal generator

302a: first coupler block

302b: second coupler block

303: power synthesis unit

402: branch line coupler

403: circularly polarized antenna

404: 90 degree phase delay block

405: combiner

The present invention relates to a circularly polarized radar device, and more particularly to a radar device having a transmission leakage signal canceller with a balanced structure.

1A and 1B are block diagrams schematically showing a linear polarization radar device having a balanced structure according to the prior art, and show a structure in which a transmitting and receiving antenna is shared. The radar device shown in FIG. 1A includes a balance signal generator 301 that generates a balance signal having a phase difference of 180 Hz, and one signal of the balance signal generated by the balance signal generator 301 through the antenna 104. Through the first coupler block 302a, the 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, and the antenna 104. A power combining unit 303 for synthesizing the received receiving signal Rx and the transmitting signal Tx leaked from the first to second coupler blocks 302a and 302b to the receiving end, and an output of the power combining unit 303 A low noise amplifier amplifies the signal through the low noise amplifier 105, the mixing of the signal of the balance signal generator 301 and the mixer 106 is composed of a receiver for outputting a baseband signal through the filter (107). At this time, since the balance signal generator 301 should use a balance signal having the same magnitude and different phases from each other by 180 Hz as an output signal of the transmitting end, 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 include a four-port coupler such as a directional coupler and a Lange coupler, a power divider or a circulator. It can be configured as a circulator. 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 magnitude and 180 ° phase difference, and outputs a transmission signal Tx amplified through 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 signal Tx leaked to the receiving end is the same in magnitude and has a phase difference of 180 ㅀ, it is canceled with each other when it is added by Wilkinson Power Combiner or T-Junction Combiner, which is a power synthesizer 303. 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.

The difference between FIG. 1A and FIG. 1B is that the power synthesizer 303 is used in the device of FIG. 1A, but the combiner is selected as a specific example to play this role in the device of FIG. In FIG. 1B, reference numeral 401 denotes a Lange coupler.

However, in the prior art device configured as described above, the signal entering the second coupler block 302b of the balance signal generator 301 is opposite in phase to the leakage signal generated by the first coupler block 302a. It only produces a leaky signal and the rest of the power is dissipated in the termination resistor, causing a loss of transmit power. In addition, in the radar device having such a structure, since only a linear polarized antenna can be used as an antenna, polarization loss occurs.

Accordingly, the technical problem of the present invention is to provide a circularly polarized radar device capable of reducing transmission and reception power loss as well as eliminating polarization loss and interference between radars, compared to a conventional radar device having a balanced structure.

In order to solve the above technical problem, a circularly polarized radar device according to an embodiment of the present invention includes: a signal generator for generating two signals having a phase difference of 180 degrees; First and second coupler blocks which receive two signals generated from the signal generator and send them to an antenna and a mixer; An antenna receiving signals from the first and second coupler blocks, the antenna being circularly polarized; A 90 degree phase delay block coupled between the second coupler block and the input of the antenna; A power synthesizer for adding received signals inputted through the antennas and removing received signals leaked from the first to second coupler blocks to a receiving end; A mixer configured to receive signals from the first and second coupler blocks, the mixer performing mixing by using a LO signal from the first and second coupler blocks and a signal from the power synthesizer; It is characterized in that the baseband signal is obtained by removing the transmission leakage signal without transmitting power loss.

The power amplifier may further include a power amplifier between the signal generator and the first and second coupler blocks, and a low noise amplifier between the power synthesizer and the mixer, respectively.

Further, each of the first and second coupler blocks may be any one selected from the group of quadrature couplers consisting of a directional coupler, a Lange coupler and a branch line coupler.

In addition, the circularly polarized antenna may be composed of two feed lines.

In order to solve the above technical problem, a circular polarization radar device according to another embodiment of the present invention includes: a signal generator for generating two signals having a phase difference of 180 degrees; Three-port element type first and second coupler blocks which receive two signals generated from the signal generator and send them to an antenna; An antenna for receiving signals from the first and second coupler blocks, the antenna comprising: a circularly polarized antenna comprising two feed lines; A 90 degree phase delay block coupled between the second coupler block and the input of the antenna; A power synthesizer for adding received signals inputted through the antennas and removing received signals leaked from the first to second coupler blocks to a receiving end; A mixer configured to receive two signals generated from the signal generator as LO signals and perform mixing using signals from the power synthesizer; It is characterized in that the baseband signal is obtained by removing the transmission leakage signal without transmitting power loss.

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 invention, but is presented by way of example only.

2 is a block diagram schematically illustrating a radar apparatus according to an embodiment of the present invention. Referring to FIG. 2, the transmission leakage signal is removed due to a 180 degree phase difference in the power combining unit 303. The signal generator 301 generates a balance signal having a phase difference of 180 degrees. The two signals from the signal generator 301 are split into two signals through the first coupler block 302a and the second coupler block 302b and one of the split signals goes to the LO signal of the mixer 106. , The other is transmitted to the circularly polarized antenna 403. Circularly polarized antenna 403 consists of two feed lines. At this time, out of the first coupler block 302a of two signals transmitted to the antenna 403 passes through the 90 degree phase delay block 404 and enters the circularly polarized antenna 403. The signal propagated through the circularly polarized antenna 403 is fitted to the target (not shown) and is again introduced through the circularly polarized antenna 403, which is moved to and from the circularly polarized antenna 403 by a 90 degree phase delay block 404. The 180 degree phase will change. Therefore, when these signals are combined in the power combiner 303, the signals coming from the first coupler block 302a and the second coupler block 302b are combined in the same phase. The output signal of the power combiner 303 is amplified by the low noise amplifier 105, mixed with the LO signal from the first coupler block 302a and the second coupler block 302b in the mixer 106, and then filtered. Filtered by 107 and output as a baseband signal. Meanwhile, the 90 degree phase delay block 404 may select a 90 degree phase delay line as a specific device. The radar device of the present invention having such a configuration implements a balanced signal leakage signal eliminator using a 90 degree phase delay block 404 and a circular polarization antenna 403, thus greatly reducing the loss of transmission power in the radar device. Can be reduced. In addition, since the circular deviation is used, polarization loss that may occur when using linear polarization can be eliminated, and the two radar apparatuses do not interfere with each other even if they face each other.

3 is a diagram illustrating a specific configuration example of the radar device of FIG. 2. 2 and 3, a combiner 405 is used in the radar device of FIG. 3 as a device corresponding to the power synthesizer 303 of FIG. 2, and the first coupler block 302a of FIG. And a branch line coupler 402 is used as the element corresponding to the second coupler block 302b. Except for this difference, since the apparatus of FIG. 3 and the apparatus of FIG. 2 operate the same, duplicate descriptions of the operation are omitted.

FIG. 4 is a block diagram illustrating a case where a three-port device such as a circulator is used as the coupler block in the radar device of FIG. 2. 2 and 4, three-port elements 302a 'and 302b' are used as elements corresponding to the first coupler block 302a and the second coupler block 302b of FIG. It can be seen that the apparatus of 4 uses the one coming from the signal generator 301 rather than from the three-port elements 302a 'and 302b' as the LO signal entering the mixer 106. Except for these differences, the apparatus of FIG. 4 and the apparatus of FIG. 2 operate identically, and thus redundant description of the operation will be omitted.

According to the present invention as described above, since the transmission power loss and the polarization loss is reduced, the waste of power is prevented, and even if two radar devices face each other, the effect of interference is small, so that the device can be easily downsized. have.

Claims (5)

A signal generator for generating two signals having a phase difference of 180 degrees; First and second coupler blocks which receive two signals generated from the signal generator and send them to an antenna and a mixer; An antenna receiving signals from the first and second coupler blocks, the antenna being circularly polarized; A 90 degree phase delay block coupled between the second coupler block and the input of the antenna; A power synthesizer for adding received signals inputted through the antennas and removing received signals leaked from the first to second coupler blocks to a receiving end; A mixer configured to receive signals from the first and second coupler blocks, the mixer performing mixing by using a LO signal from the first and second coupler blocks and a signal from the power synthesizer; Circular polarization radar device having a baseband signal by removing the transmission leakage signal without transmitting power loss. The circularly polarized radar device of claim 1, further comprising a power amplifier between the signal generator and the first and second coupler blocks, and a low noise amplifier between the power synthesizer and the mixer, respectively. The circularly polarized radar device of claim 1, wherein each of the first and second coupler blocks is any one selected from the group of quadrature couplers consisting of a directional coupler, a Lange coupler, and a branch line coupler. The circularly polarized radar device according to claim 1, wherein the circularly polarized antenna consists of two feed lines. A signal generator for generating two signals having a phase difference of 180 degrees; Three-port element type first and second coupler blocks which receive two signals generated from the signal generator and send them to an antenna; An antenna for receiving signals from the first and second coupler blocks, the antenna comprising: a circularly polarized antenna comprising two feed lines; A 90 degree phase delay block coupled between the second coupler block and the input of the antenna; A power synthesizer for adding received signals inputted through the antennas and removing received signals leaked from the first to second coupler blocks to a receiving end; A mixer configured to receive two signals generated by the signal generator as LO signals and perform mixing using signals from the power synthesizer; Circular polarization radar device having a baseband signal by removing the transmission leakage signal without transmitting power loss.

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