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Abstract-This paper presents a novel effective calibration technique applicable to phased array radars. The real embedded patterns of the array elements are measured independently in operating mode, taking antenna coupling and other parasitic effects into account. The proposed calibration technique requires minimal modification of the radar hardware. A set of angular-dependent error coefficients, which are compensated during the calibration process, are extracted for one received pulse for one/each angular direction of interest. The performance and effectiveness of the here-proposed calibration technique are assessed by means of modeling and experimental verification.

Introduction. With the development of hardware and computer systems, which improve qualitative characteristics of synthetic aperture radars, with their dimensions limited, many new systems have appeared that allow using more accessible and widespread mobile platforms such as a car, quadcopters, unmanned aerial vehicles (UAV). Problem. The use of new types of platforms leads to additional distortions associated with features of the geometry of the radar performance and more severe trajectory instabilities. Thus, new synthetic aperture radar systems should have special requirements for both software and hardware, which differ from classical systems. Objective. The aim of the work is the comparison various algorithms that are used in modern radiovision systems to obtain high-quality radar images that can be integrated into various kinds of mobile platforms. Methods. The method of frequency scaling and various modifications of this method are taken as a basic algorithm, including additional algorithms for compensating trajectory instabilities. For comparison of algorithms, the system geometry for automobiles and aircraft systems are considered and simulations were performed with the presence of point reflectors at different distances and the distortion of the platform motion. Results. The difference of the considered algorithms in the form of flowcharts and mathematical formulas is shown. Based on results of the simulation the use of the basic frequency scaling algorithm at distances corresponding to the geometry of the automobile system leads to the distortion of the response along the azimuth. In addition, the use of the modified algorithm for compensating trajectory distortion allows correct focusing the targets at different distances. Conclusion. The proposed combination of modified algorithms of trajectory distortion and frequency scaling allows focusing the image evenly throughout the frame and improving the quality of the image in the near zone.

This article discuss analog methods of direct patch interference cancellation in receiving channel of passive location system, which use signals from opportunity. The analog method of transmitter signal cancellation in receiving channel for passive multi-position location systems is proposed. Experimental results for proposed method are considered.