• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.1
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• pp.73-79
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• 2020

Modern radar system requires high spectral purity and low phase noise characteristics for very low RCS target detection and high resolution SAR (Synthetic Aperture Radar) image. This paper presents a new X-band high stable frequency synthesizer for high performance radar system, which combines DAS (Direct Analog Synthesizer) and DDS (Direct Digital Synthesizer) techniques, in order to cope with very low phase noise and high frequency agility requirements. This synthesizer offers more than 10% operating bandwidth in X-band frequency and fast agile time lower than 1 usec. Also, the phase noise at 10kHz offset is lower than -136dBc/Hz, which shows an improvement of more than 10dB compared to the current state of art frequency synthesizer. This architecture can be applied to L-band and C-band application as well. This frequency synthesizer is able to used in modern AESA (Active Electronically Scanned Array) radar system and high resolution SAR application.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1139-1147
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• 2011

In this paper, a design and fabrication of GaN power amplifier for the S-band frequency (400 MHz bandwidth) are presented. A combining path using ${\lambda}$/4 transmission line is implemented for GaN pallet amp. Both the combiner with suspended-type transmission structure for low-loss and the suspended stripline coupler with aperture coupling for auto gain control are realized for achieving high-power high-efficiency amplifier. Proposed power amplifier demonstrated a 5 kW peak output power, 27.8 % efficiency, 67 dB gain without ALC and a 4 kW peak output power, 25.5 % efficiency, 0.1 dB droop at 200 usec pulse width and 10 % duty with ALC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.196-206
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• 2012

AESA radar is able to instantaneously and adaptively position and control the beam, and such adaptive beam pointing of AESA radar enables to remarkably improve the multi-mission capability, compared with mechanically scanned array radar. AESA radar brings a new challenges, radar resource management(RRM), which is a technique efficiently allocating finite resources, such as energy and time to each task in an optimal and intelligent way. Especially radar beam scheduling is the most critical component for the success of RRM. In this paper, we proposed stochastic radar beam scheduling algorithm using simulated annealing(SA), and evaluated the performance on the multi-function radar scenario. As a result, we showed that our proposed algorithm is superior to previous dispatching rule based scheduling algorithm from the viewpoint of beam processing latency and the number of scheduled beams, with real time capability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.172-182
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• 2014

In this paper, is is presented the result of design and fabrication for X band T/R module using in active array radar. The high power RF circuit was fabricated using GaN element, so that high power and high efficiency was fulfilled comparing with the previous T/R module that have under 50 W output power for X band. Designed X band T/R module demonstrated 200 W(53 dBm) peak power, 20 us pulse width with 0.4 dB pulse droop and 20 % duty cycle. And it has characteristics of 26 dB receive gain and 4.5 dB noise figure. The structure was applied to prevent serious damage of receive path and GaN HPA by transmitting power during trasmit time of a pulse radar.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.12
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• pp.1380-1387
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• 2012

The transmit/receive(T/R) module is a key component in the active phased array system. The brick-type T/R module has been widely used and the miniaturization has been an important factor to get the flexibility of the system configuration. For the miniaturization, multi-function chips(MFC) having a common leg configuration are suitable to reduce the number of required MMICs and a high isolation between transmit and receive paths is necessary for the high gain T/R modules. In this work, we propose a bias timing scheme for the compact T/R module and show the optimum timing based on measurements, in order to improve the feed-back path loop problem and the consequent isolation problem of the common leg configuration. We have implemented high power(7 W/channel) and high T/R gain(35 dB transmit and 30 dB receive gains) within the half size($140{\times}80{\times}16mm^3$) of the conventional T/R modules.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.540-545
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• 2023

AESA radar is able to instantaneously and adaptively position and control the beam, and this enables to have interleaved mode in modern airborne AESA radar which can maximize situational awareness capability. Interleaved mode provides two or more modes simultaneously, such as Air to Air mode and Sea Surface mode by time sharing technique. In this interleaved mode, performance degradation is inevitable, compared with single mode operation, and effective resource allocation is the key component for the success of interleaved mode. In this paper, we identified performance evaluation items for each mode to analyze interleaved mode performance and proposed effective resource allocation methodology to achieve graceful performance degradation of each mode, focusing on detection range. We also proposed beam scheduling techniques for interleaved mode.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.580-586
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• 2023

AESA radar is able to instantaneously and adaptively position and control the beam, and this enables to greatly improve multi-target tracking capability with high accuracy in comparison to traditional mechanically-scanned radar system. This paper is primarily concerned with the development of an efficient methodology for multi-target managenent with the context of multi-target environment employing AESA radar. In this paper, targets are stratified into two principal categories: currently displayed targets and non-display targets, predicated upon their relative priority. Displayed targets are subsequently stratified into TOI (target of interest), HPT (high priority target), and SAT (situational awareness target), based on the requisite levels of tracking accuracy. It also suggests rules for determining target priority management, especially in air-to-air mode including interleaved mode. This proposed approach was tested and validated in a SIL (system integration lab) environment, applying it to AESA radars mounted on aircraft.

• Journal of the Korea Society of Computer and Information
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• v.29 no.3
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• pp.117-125
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• 2024

In this paper, implement and propose an Active Electronically Scanned Array (AESA) radar integration analysis system which specialized for radar development by using heterogeneous media. Most analysis systems are used to analyze and improve the cause of defects, so they help the test easier. However, previous log analysis systems that operate only based on text are not intuitive and difficult to find the information user want at once if there is a lot of log information. so when an equipment defect occurs, there are limitations in analyzing the cause of defect. Therefore, the analysis system in this paper utilizes heterogeneous media. The media defined in this paper refers to recording text-based data, displaying data as image or video and visualizing data. The proposed analysis system classifies and stores data that transmitted and received between radar devices, radar target detection and Tracking algorithm data, etc. also displays and visualizes radar operation results and equipment defect information in real time. With this analysis system, it can quickly provide information what user want and assistance in developing high quality radar.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.573-582
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• 2010

In this paper, X-band transceiver for high resolution wideband SAR systems is designed and fabricated. Also as a technique for enhancing the performance, error compensation algorithm is presented. The transceiver for SAR system is composed of transmitter, receiver, switch matrix and frequency generator. The receiver especially has 2 channel mono-pulse structure for ground moving target indication. The transceiver is able to provide the deramping signal for high resolution mode and select the receive bandwidth for receiving according to the operation mode. The transceiver had over 300 MHz bandwidth in X-band and 13.3 dBm output power which is appropriate to drive the T/R module. The receiver gain and noise figure was 39 dB and 3.96 dB respectively. The receive dynamic range was 30 dB and amplitude imbalance and phase imbalance of I/Q channel was ${\pm}$0.38 dBm and ${\pm}$3.47 degree respectively. The transceiver meets the required electrical performances through the individual tests. This paper shows the pulse error term depending on SAR performance was analyzed and range IRF was enhanced by applying the compensation technique.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.241-249
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• 2022

This paper discusses the design of a ground clutter prevention fence for a radar wind profiler (RWP). The design point of the clutter fence is to improve the quality of the received signal by removing the non-weather clutter coming from the side. In this paper, a clutter prevention fence composed of a metallash mesh around the RWP is proposed, and the phase center of the antenna, the length, and height of the down fence, and the height and slop of the top fence through M&S are designed. The designed ground clutter prevention fence and 256 active phase array antennas were used as basic data. The effectiveness of the design was confirmed by a simulation. The side lobe in the ±90° direction was reduced by more than 30dB depending on the presence or absence of the designed ground clutter prevention fence. The fence was manufactured by 3D modeling, and the clutter shielding performance of approximately 20dB or more on the side of the antenna (±90°) was confirmed by applying it to the currently operated RWP.