| High-frequency ground wave radar (HFGWR) can be used in a system of bis/multi-static radar, which exerts the advantage of HFGWR in detection of over-the-horizon (OTH). At the same time, due to properties of location precision and anti-invisible of bis/multi-static radar, the detection range of HFGWR is able to be extended. In order to study the characteristics of above-mentioned radar system, as well as present the theoretical basis for selecting proper scheme in signal processing, this dissertation is focused on the research: target echoes model, frequency of sea clutter and scatter model of HFGWR under bis/multi-static condition.Compared with monostatic radar, it is more complex in systemic structure and data processing in bis/multi-static radar. Due to the character of bistatic-radar, the scatter process of target echoes in the bis/multi-static radar is strongly influenced by the bistatic angle. Consequently, the structure of bistatic should be considered as a major factor when studying the model of target echoes as well as sea clutter echoes. Firstly, this dissertation defines a coordinate for geometrical structure of bistatic radar, analyze the geometrical structure in detail, discuss the detection area based on a principle of energy constraint, compare the detection areas between monostatic radar and bistatic radar. At the same time, target location method of bistatic radar is studied, then the location precision is compared under simulation with different parameters. Based on these researches, disposition of the multistatic radars is discussed.Secondly, this dissertation analyzes extractive process of information which includes distance and velocity of target in detail. The parameters of distance and velocity are not only related to echoes delay, but also decided by geometrical location of transmitter and the receiver. Consequently, a new simulation method, which is based on an iterative process, is presented for simulation of motive target here. Moreover, on the basis of this simulation method, a comparison is outlined with a series of parameters in different motive states. In addition, target scatter properties are compared under bistatic radar and monostatic radar.Then, the characteristics of sea clutter of bistatic high-frequency radar are studied. The scatter frequency of bistatic high-frequency sea clutter is not only related to the transmitter frequency, but also depended on bistatic angle of echoes location. Corresponding to different mechanisms of second-order diffraction of sea clutters, sea clutter could be classified into three categories, and the corresponding scatter and coupling coefficients are different. This dissertation emulates first-order and second-order sea clutter, compare the differences under monostatic and bistatic radar and discuss factors influencing scatter spectrum.In the end, this dissertation presents the simulation system, comprising data, structural frame and data processing of this software for radar. For the further study, one provides hardware theoretical scheme for the afterwards data output as well as study the theoretical designing of hardware circuit for signal simulator. |
PDF Full Text Request