High-frequency combined sky-wave and surface-wave monostatic radar (CSSM-HF RADAR) is a new type of radar system inspired by the skywave components of high-frequency surface-wave radar (HFSWR). The new type of radar uses the combined propagation paths of skywave and ground wave to detect targets, including four paths without considering ionospheric stratification. The related research of the CSSM-HF RADAR is relatively rare, and this paper carries out a detailed simulation analysis of its coverage area. Coverage area analysis is significant for subsequent work, such as target detection, frequency selection, and echo propagation path matching. In this paper, the signal-to-noise ratio (SNR) in the atmospheric background is derived at first, and then the parameters that change with propagation paths are analyzed. Finally, the coverage area of each propagation mode is calculated by setting the minimum detectable SNR. The simulation results show that the coverage areas of the four propagation paths at low frequency have overlapping regions. As the operating frequency increases, the coverage area of each propagation mode gradually separates, and some areas that cannot be covered may appear, however, the whole coverage area of the CSSM-HF RADAR increases.
Abstract:In high-frequency surface wave radar (HFSWR), part of the radiation signal inevitably propagates upward and illuminates the target through the ionosphere due to the poor controllability of the antenna's vertical pattern. As a result, a target may have several echoes from different propagation modes, which affect target detection and tracking and is usually unmanageable in existing HFSWR systems. Without the information of the elevation angle, it is difficult to distinguish the propagation mode of measurements during the target detection phase. This paper makes the first attempt to propose a multi-mode target tracker for HFSWR to solve this problem during the target tracking phase. The multipath probability data association (MPDA) tracker is capable of exploiting multipath target signatures of discrete propagation modes and has been widely used. Based on this, we construct a modified multi-mode probability data association tracker for HFSWR to suppress false tracks caused by multiple propagation modes. Numerical simulations demonstrate that this novel tracker can effectively and accurately track the target from the measurements under multiple propagation modes in HFSWR. The processing results of the actual data collected in Weihai, China indicate that this tracker is of great significance for practical applications.
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