• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.528-536
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• 2010

A monopulse feeder gives the most important impact upon the radiation pattern characteristics of a multi-function radar or a tracking radar which uses the space feed. It is described that the triple-mode type monopulse feeder which possesses the optimum aperture illumination for three monopulse channels is designed and measured in this paper. The measured results show that the designed feeder has not only the characteristics of the optimum aperture illimination in each channel and also very low return loss over the 10 % of fractional bandwidth at X-band. This means that the feeder provides the antenna system with low sidelobe level and high monopulse slope characteristics.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.109-114
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• 2024

The effect of inter-channel coupling in multi-channel monopulse receiver is expected to increase by miniaturization trend of receiver. Therefore, in this paper, calibration method is proposed to compensation for inter-channel coupling in receiver of monopulse radar. And it can prevent distortion of angle information of target. Hardware configuration that consists of switch, directional coupler, matched load, ADC(Analog to Digital Converter), signal source of calibration is proposed to calibration. Total nine scattering parameters are obtained by controlling the switch and signal source of calibration. After that, method for restoring the undistorted signal is proposed using the mathematical relationship between the monopulse signal output from the antenna and the monopulse signal passing through the multi-channel receiver in the presence of inter-channel coupling.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.82-85
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• 1987

Electromagnetic waves from the satellite may be utilized to direct the tracking antenna toward the satellite. We design and fabricate the feed appropriate to the monopulse tracking technique which derive angle-error information on the basis of a single pulse. The feed consists of five cavity-backed turnstile elements mounted on a common ground plane. The turnstile dipole are connected to a set of five quadrature hybrids which convert the dual linear polarization into dual circular polarization. The five feed outputs are then processed in the monopulse comparator which is constructed in microstrip for compactness.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.115-121
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• 2012

In this paper, the design and fabrication of slot array in the broad wall of the waveguide for Ka-band monopulse radar are discussed. The aperture distributions are designed for the desired antenna gain, beamwidth and Side-lobe Level(SLL), and then slot parameters, such as lengths and offsets, are obtained for corresponding to each slot admittance in the equivalent circuit by using Elliot's array synthesis procedure. MWS-CST simulation shows the return loss below -10 dB, antenna gain above 32 dBi, 3 dB beamwidth of 3.7 degree and SLL of -20 dB. In order to demonstrate the expected results, the designed antenna is fabricated and measured.

• Journal of the Korea Society for Simulation
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• v.28 no.3
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• pp.75-82
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• 2019

A Satellite Communication (SATCOM), which is applied to various systems to communicate with other systems at the limited wired communication situation, is required to head at a stable point of the space, because this system uses a geostationary satellite. It is important to know satellite tracking heading angles such as elevation angle and azimuth angle for the immovable antenna's latitude, longitude, and altitude. Moreover, calculation of heading angle is critical for SATCOM antenna on a moving platform. In this study, a antenna heading angle calculation method is applied to compute elevation and azimuth angle for a SATCOM antenna and the heading angle simulation is executed for the Korea peninsula and surrounding areas. To verify this simulation, satellite tracking test is conducted using a SATCOM antenna which uses monopulse signal tracking method. The simulation is confirmed by comparing this test result with the simulation. And we make a suggestion for calculation of polarization angle of this antenna.

• 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.19 no.3
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• pp.363-370
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• 2016

This paper proposes a Ku-band multi-mode coupler and its monopulse tracking system, which can be applied to a unmaned aircraft vehicle(UAV) platform. In general, the carrier-to-noise(C/N) level of the beacon signal from a Ku-band commercial satellite is relatively weak compared to that of a military satellite because the Ku-band satellite has been designed for commercial services. Therefore, this paper proposes a coupler and its multi-mode monopulse tracking system satisfying the tracking accuracy under a low C/N environment and analyzes the tracking accuracy. After that, we perform a real satellite tracking test and compare the accuracy of the test with the analysis result before validating the performance of the architecture of the proposed satellite tracking system.

• Journal of the Korean Professional Engineers Association
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• v.42 no.6
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• pp.53-57
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• 2009

Antenna Tracking System has been required core technology with special tracking algorithm, and it can be achieved by program tracking, step tracking, optracking, and monopulse tracking as well. Depend on tracking requirement we might be able to apply eligible tracking method in accordance with Geostationary and Inclined Orbit Satellite. Further, we should deeply consider two important factors in order to act up to customer expectation in quality and system performance including competitive price therefore we need maximized endeavor to upgrade not only tracking system performance, but reduction of product through engineering skill and R&D investment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.4
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• pp.380-386
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• 2014

In this paper, a higher-order mode coupler using coaxial-structure waveguide for Ku-band monopulse satellite tracking is proposed. The proposed higher-order mode coupler is built in a coaxial structure for compactness and weight reduction, making it suitable for mobile tracking systems. The inner circular waveguide of coaxial-structure is used to extract the fundamental mode signal and the high-order mode signal is extracted from the four slots of the outer circular waveguide and then transmitted via given stepped rectangular waveguide structure. The simulated results show that proposed higher-order mode coupler covers 250 MHz(12.75 GHz ~ 13.00 GHz) bandwidth with return loss and insertion loss characteristics. The antenna patterns of fundamental mode and higher-order mode applicable to monopulse tracking are generated successfully. Designed higher-order mode coupler using coaxial waveguide structure for Ku-band is expected to be used for high precision monopulse satellite tracking systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.47-53
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• 2023

In this paper, We designed a waveguide-type feed structure that converts millimeter wave dual-polarized signals into monopulse signals and presented a manufacturing method. At millimeter-wave such as the W band, the size of the waveguide is very small, making it very difficult to manufacture complex structures. Therefore, because manufacturability is important for the waveguide-type feed structure in the millimeter-wave, electro forming and diffusion bonding were proposed and verified in this study. The designed monopulse feed structure consists of eight 180° hybrids that combine 90° hybrids and self-compensating phase shifters, and four OMTs to separate dual polarization. The designed feed structure was designed to facilitate electro forming and diffusion bonding, and the manufactured feed structure was verified through a network analyzer. It was confirmed that the two proposed production methods produce a monopulse signal well through the measured magnitude and phase of the port.