An 3D radar system can detect the distance, azimuth, and altitude of targets. The radar acquires target information using an electronic or mechanically steered narrow antenna pattern. It calculates the target altitude using the detected information. In addition, angular accuracy is improved by applying various methods such as monopulse. The radar angular accuracy is affected by external factors such as multipath effects that are caused by various factors such as the radar installation environment and the flight altitude of the target. Radar systems apply various methods to improve the detection accuracy degradation caused by multipath effects. The squinted sum monopulse method can reduce the detection errors of the radar in a marine environment with a high frequency of multipath effects. The radar utilizes a different monopulse pattern that calculates an angular error with a sum pattern steered upwards of the detection beam. This is a method of minimizing the influence of the multipath received signal incident downward through a difference pattern in which the gain falls sharply below the detection beam. In this study, the effect of the squinted sum monopulse method was verified through simulation, and the effect was confirmed by applying it to an early warning radar installed in a sea environment condition.
It is essential for the near-field receiving measurement to make beam pattern and check the performance of a active phased array antenna system. Also, we could obtain compensation value for mono-pulse function through the near-field receive test, however, if the radar has many frequency channel, the test would take long time and hard effort. So it is needed that frequency channels are selected for measurement and calculates the values for other frequency channels to improve efficiency in development and manufacture. In this case, the phase variations in sum and del channels would be checked. The phase measurement includes un-linear characteristic because of wrapping effect. Generally, radars have similar path length in sum and del channel, but if a radar has a electrical length gap between sum and del channel, errors could occur by phase's wrapping effect. In this paper, the interpolation method's error caused by electrical length gap is checked and the effective method for frequency channel selection to avoid wrapping effect is introduced.
It is necessary to check the fault of phased array antenna, when the active phased array radar installed in the site is suspected performance degradation due to external impact or long-term operation. However, the near -field test should be performed in anechoic chamber in order to measure the phased array antenna, so that much time and cost must be applied for radar disassembly and transportation, and the operational availability of the radar system is deteriorates. Therefore, we propose a near-field scanner with mobility to check the fault of the phased array antenna at the site, and the effectiveness of the proposed scanner was verified with ±0.5dB magnitude and ±1.5°phase in comparison with measured data in anechoic chamber.
The study aims to a design hybrid frequency synthesizer in spectrum analyzer and to propose new techniques designed for evasion of in-band spurious. The study focuses on calculating the exact location of multiple phase locked loop of hybrid frequency synthesizer and spurious of direct digital synthesizer to evade in-band spurious outside of frequency range that the user wants to see and thereby simulating technique to improve input related spurious of spectrum analyzer for algorithm. The proposed technique is designed to calculate spurious evasion algorithm in central processing system when in-band spurious arises, and to move output frequency of DDS(direct digital synthesizer) into the place where no in-band spurious exists thereby improving performance of frequency synthesizer. The study used simulation and result representation to prove the effectiveness of the proposed technique.
This paper describes that how to enhance the robustness of semiconductor TRM(Transmitter and Receiver Module) through the bias sequencing and tuning the switching time. Previous circuit designs focused on improving the MDS(Minimum Detection Signal) performance. Because TRM has critical problem which transmission output signal leak into receiver by it's compact design. Under this condition, TRM was frequently broken down within the MTBF(Mean Time Between Failure). This study proposes the bias sequencing and tuning the switching time to improve above problem. At first, we collected major failure symptom and infer it's cause. Second, we demonstrated it's effect by derive the improvement method and apply it to our system. And finally we can convinced that the proposed method clear the frequent failure problem with its lack of isolation.
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