Research On Ionospheric Characteristics And Integrated Radar Frequency Selection Methods Over High Frequency Band

As a new radar system, high-frequency surface wave radar has more excellent detection performance but inevitable has its limitations and shortcomings, mainly reflected in failing to survive in the high frequency band. High frequency radar work in complex electromagnetic environment, various kinds of interference and noise are frequency related. In addition, the radar target cross section and surface wave propagation attenuation characteristics are also related to the radar operating frequency. Improper frequency selection will lead to the radar leakage alarm and detection range reduced. The main contents of this paper is to consider the above factors impacting on optimization of work frequency in high frequency ground wave radar, a maximum SCNR criteria are established as a optimal function for high-frequency surface wave radar systems. Design and archive user interface system for optimization of work frequency in high-frequency surface wave radar . The main contents are as follows:First, ionospheric disturbances are an important factor in the optimal frequency system of high-frequency surface radar. This article describes the mechanism of electromagnetic waves propagation in the thermosphere, the critical frequency and peak height of each layer will be predicted. Ionospheric absorption loss characteristics and ionospheric echoes of high frequency surface wave radar will be discussed. Several possible mode of transmission are proposed.Second, we firstly derive the High frequency surface wave radar equation, and then study Transmission attenuation characteristics of the high frequency electromagnetic wave propagation along the uniform and smooth sea. Finally, Radar cross section (RCS) of given radar target will be discussed.Third, through the study of several possible echo routes in ionospheric echo interfere, we proposal the concept of four single working mode and the combination of the four in ionospheric echo interfere. Then we simulate echo interference route of the two ionospheric propagation mode, and the whole propagation loss of each path. Thirdly, we use the backward scattering energy algorithm to compute the ionospheric echo energy in the target unit distance. we prediction environmental noise coefficient, environmental noise generally decreases with frequency increase. we also discuss the sea clutter impact of the echo signals, especially the first-order sea clutter occlusion on the target, introduce second-order sea clutter energy calculating method through the discussion of second-order scattering coefficient.Finally, we involve optimization structure of high-frequency surface wave radar frequency system, establish optimization frequency rule of the largest SCNR (Signal to Clutter and Noise Ratio). After introduced each part of the calculation and implementation processes, we finally gives the whole calculate process of frequency optimization system in high-frequency surface wave radar. In the end, the whole frequency optimization system and the GUI of high-frequency surface wave radar are archived.