• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.1
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• pp.94-102
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• 2018

In this paper, the wideband mono-pulse radar using AGC and limiter is designed. The output response characteristics of the mono-pulse radar using AGC and limiter are analyzed, respectively. In addition, the output response for jamming input signals is analyzed. The range tracking loop in the mono-pulse radar has robust output response to the noise jamming input signal. Although the output settling response of the AGC-based mono-pulse radar is larger than that of the limiter-based mono-pulse radar, the AGC-based mono-pulse radar has robustness to the noise jamming input signal due to feedback loop.

• Journal of Convergence for Information Technology
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• v.10 no.6
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• pp.14-18
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• 2020

In this paper, when two sets of cross-eye jammer antennas are installed vertically to jam a monopulse radar, the jamming effects according to the jammer's phase difference, amplitude ratio, and radar angle of engagement are analyzed. The phase difference and amplitude ratio of the cross-eye jammer can be adjusted in the jammer, but since the angle of engagement is relatively determined by the radar, it is very important to respond to changes in the angle of engagement. The orthogonally deployed jammer antennas can be considered as a good way to increase the jamming effect while minimizing the hardware configuration, and the jamming effect is analyzed while changing the angle of inclination from 0° to 360°. This jammer greatly improves the jamming effects at the angles of incidence 45°~135° and 225°~315°, compared to a single jammer. And it is expected to be useful in the design of cross-eye jammers for military aircraft and ships.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.3
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• pp.410-413
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• 2012

This study describes the performance comparison to solve angle ambiguity needed to angle of arrival estimation in 2D radiometer. There are three algorithms to solve its ambiguity such as phase-comparison monopulse method, digital beam-forming method and least square error of the phase difference in 2D radar interferometer. To estimate two direction angles, phase-comparison monopulse method is sequentially applied to azimuth and elevation direction. To analyze the performance of these methods, probability of solving angle ambiguity and execution time have been chosen as performance indexes. Through the Monte Carlo simulation, we have verified that phase-comparison monopulse method is most effective in real-time signal processing application.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1248-1258
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• 2010

In this paper, a method for simultaneously realizing the sum and difference patterns which are required in the monopulse radar sensor systems, is presented by using single taper array antenna with rectangular microstrip patches. The widths of patches are first determined by the voltage weights which are synthesized for the fundamental array factor patterns to be applied to the monopulse operation by using the sidelobe levels(SLLs) control technique. As the bi-directionally series-fed technique is applied and the lengths of connecting lines between patches are appropriately adjusted, the single array generates two phase-shifted beams which activates out-of-phase and in-phase ports of a $180^{\circ}$ hybrid coupler to synthesize the sum and difference patterns. The simulated results on the configuration designed at 9.5 GHz are compared with measured results showing the validity of the proposed method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.577-580
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• 2016

One of the effective jamming methods to disturb monopulse radars is a wavefront distortion. Most well-known wavefront distortion is the cross eye technique which uses two transmitters. The cross eye can make angle error regardless of monopulse radar structure but high accuracies of phase and amplitude between two transmitters should be needed to make large angle error. Thus, the accuracies of phase and amplitude are essentially required performance parameters for implementation of wavefront distortion systems and the required values of accuracy is dependant on amount of angle error. In this paper, we derive expressions for minimum required values of phase difference and amplitude ratio according to amount of angle error and analyze the results.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.365-372
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• 2013

The multibeam surveillance radar is a state-of-art of 3D radar technology. It applies the stacked beams realized by a digital beamformer. In this paper, a hybrid compensation technique on elevation angle errors for low elevation angle targets over the sea in multipath radar environments is proposed. The proposed method can be applied to stacked beam radars. Double null algorithm based on maximum likelihood method in 3-D beamspace domain works well unless the phase difference between the two rays(direct and specular path) is close to $0^{\circ}$ and the magnitude of reflection coefficient is close to 0. To overcome these problems, we propose a hybrid compensation technique which uses the selective double null algorithm and the beam-ratio compensation technique for low-elevation errors on a log scale. Results of computer simulation show that the proposed method outperform conventional monopulse method and double null algorithm only under various multipath environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.999-1002
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• 2017

For a target echo containing interference, it is very difficult to improve the performance of a monopulse radar with spatial domain processing, because the statistical property of interference cannot be exclusively obtained. This paper proposes a monopulse system that has a generalized sidelobe canceller(GSC) filter-based time domain processor as a preprocessor prior to conventional monopulse spatial processing. We analytically show the procedure of time-space signal processing running in the system, and assess its performance through simulation. In particular, the performance dependence on the number of taps in the main channel filter and the estimation error in Doppler frequency are assessed by comparison with those of existing systems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.11
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• pp.69-76
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• 2010

From the present paper we researched about the design of 4-Way Wilkinson divider with waveguide to stripline transition which used to split the LO signal with equi-amplitude and equi-phase in the X-Band Monopulse radar RF front-end. The monopulse radar front end operating in the X-Band is composed of 3 waveguide reception mixers which down convert sum, azimuth and elevation signal to IF and one SSB waveguide mixers which generate X-Band test signal. It is required the 4-way divider with low loss, equi amplitude and equiphase splitting the LO signal to provide the LO signal to each mixer consisting RF frontend. In this paper we designed and fabricated the 4-Way Wilkinson divider with waveguide transition to divide the LO signal into equi-amplitude and equi-phase. The fabricated Wilkinson divider have the insertion loss 6.8dB, VSWR 1.06~1.28, and phase balance maximum 4.5degree for each output ports.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.27-32
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• 2018

In this paper, W-band transceiver module for compact radar has been designed and fabricated. Utilizing proposed microstrip-to-waveguide transition, the error between design and implementation is reduced. The proposed transition provides less than 1 dB insertion loss per transition and reliability for fabrication. In order to apply compact radar with dual-polarized monopulse directly, W-band transmitter with 28 dBm output power is designed and developed. Also, 6 channels of receiver module with low noise figure 13.5 dB and maximum 17 dBm input P1dB is developed. Proposed W-band transceiver module is expected compact radar application for dual-polarized monopulse signal processing system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.235-244
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• 2014

This paper describes the subarray channel configuration and calibration method for airborne AESA radar antenna. AESA radar demonstrator was designed and implemented for the digital beam-forming performance test of the 12 channel subarray structure. Magnitude and phase difference can be exist between the manufactured subarray channel. In this paper, calibration method for the subarray difference error was suggested. We measured digital monopulse slope in the subarray channel and verified the channel calibration effect. To verify the subarray channel operation, digital monopulse channel was compared with analog monopulse channel performance. AESA radar demonstrator was tested in the ground far field test range. Emulated single target was generated to test the detection and tracking performance of the demonstrator with the same waveform and search pattern. We verified that the detection and tracking performance of the 12 subarray digital monopulse channel was similar with the conventional analog monopulse channel. Also, ABF(Adaptive Beam-Forming) function for the sidelobe jammer was tested and effective operation was verified.