• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.4
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• pp.368-373
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• 2021

This paper presents a method of independent pulse repetition frequency(PRF) generation and control for frequency phase calibration on mono-pulse radar at a remote location. In order to generate an independent PRF signal of 320[Hz], pulse width modulation(PWM) of 16-bit timer/counter was applied. For a precision control of PRF signal, 16-bit timer/counter interrupt was changed for each period. Therefore, average frequency of PRF could be controlled by 0.0001[Hz]. To calibrate a frequency phase of mono-pulse radar at a remote location, the proposed PRF generator with a precision control of frequency was used regardless of receiving PRF signal from a radar. For the verification of the proposed PRF generator, theoretical analysis and experimental results are included.

• 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 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.7
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• pp.720-728
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• 2011

In this paper, development of the monopulse secondary surveillance radar antenna which can be used for IFF system is presented. This antenna that is passive linear array is comprised of the row-feeder and several array-elements. The row-feeder provides sum, different and SLS(Sidelobe Supression) channels which are optimized the distribution of the power and phase ratio. The azimuthe sidelobe level of the sum channel beam pattern is -20 dBc or less. The SLS channel covers the sidelobe of the sum-chanel in the whole azimuth angle range. And the difference channel is used to perform the mono-pulse function, improves the detection accuracy in the azimuth direction. Meanwhile, the arrayelement makes shaped beam in the elevation angle, in order to eliminate the clutter and multipath effects from the ground. Performance of the antenna developed is verified by the measurement of S-parameters and far-field beam pattern, and satisfies all of the development specifications well.

• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.748-751
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• 2012

The performance of a monopulse estimator is depend on its monopulse ratio(MR) curve. To improve its performance, a mathematical expression of the MR curve that is associated with an array the parameters is needed. In this paper, we present a novel monopulse estimator that uses the inverse function of a MR curve for the Maximum Likelihood (ML)-based monopulse estimator. It is shown that the proposed method can extend the linear region of the MR curve, which in turn improve the estimation accuracy. Moreover, it's performance is compared with the ML-based method through simulation.

• 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.20 no.10
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• pp.1042-1049
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• 2009

Design and optimization of a broadband waveguide magic-T was performed for X-Band tracking radars. A multi-stepped conducting cylinder was used to enhance the bandwidth performance of the conventional waveguide magic-Ts. Particles swarm optimization in conjunction with genetic algorithm was employed to obtain the optimized geometrical parameters. The optimized design exhibits low reflection coefficient below -20 dB at all waveguide ports with frequency bandwidth of 12%. The transmission loss and difference are within 0.2 dB and 0.1 dB, respectively. Measured results are also shown to be in good agreement with the simulated results. Finally, the bandwidth performances for five and seven-stepped conducting cylinders are also investigated.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.6
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• pp.34-40
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• 2011

From the present paper researched about the Design of Image Rejection SSB Modulator for X-Band Monopulse RADAR using Waveguide Hybrid Coupler. Generally, SSB modulator mixes IF(RF) and LO signals, and then it converts to RF(IF) frequency band. In this case, in order to transmit one sideband from RF band, SSB modulator is demanded the removal of image and LO signal. The balanced mixer was designed using waveguide hybrid coupler and crystal mixer diode to mix LO and IF signal. And also the IF Amplifier was designed for IF(+) and IF(-) signal generation which have $90^{\circ}$ phase differences which are suitable in two crystal mixer diode inputs. In order to maintain a high electric reliability from high frequency band the waveguide and IF amplifier's case were manufactured with aluminum using deep brazing techniques. The test result of SSB modulator, LO and sideband signal rejection ratio were 14.2dB and 18.5dB respectively.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.5
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• pp.583-590
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• 2018

Cross eye technique was proposed as an angle deception jamming technique against monopulse radars. Tracking radars use monopulse or conical scan methods for angle estimation of a target. Thus, if we verify deception performance of cross eye technique against a conical scan radar, efficient jamming systems can be developed to disturb both monopulse radars and conical scan radars. In this paper, we propose a mathematical model for a conical scan radar and a cross eye system. Using the proposed model, angular deception performance of the cross eye technique against conical scan radar is analyzed.