| As a new radar concept, Ultra-WideBand (UWB) radar has been attracting more and more students and researchers to pay attention to it for twenty years, but there are a lot of technical and practical difficulties in its true application. UWB antenna is one of the key parts of UWB radar system. The antennas for UWB application must satisfy the following requirements: big relative bandwidth, high directivity, stationary phase center and waveform fidelity. The common wide-band antenna usually can't be used in UWB application because of frequency dispersion and lower efficiency, such as spiral antenna and log-periodic dipole array.All the works of this paper include the design of rectangular dual ridged TEM horn antenna, improvement to a planar TEM horn, ultra-short pulse radiation experiment and analysis of key techniques of HPW UWB radar.Firstly, characteristic impedance of ridged paired strip is calculated by FDTD method, and its relation with antenna size is concluded, on which the design of ridged TEM horn antenna is based. The antenna is operated in the band of 150-1000MHz. Then the software, Microvave Studio? is used to simulate the huge-size TEM horn antenna. The simulated VSWR and radiation patterns are compared with measured results of the prototype antenna, and good agreement is obtained. Thirdly, a planar TEM horn is simulated by this 3D EM software and was modified to meet the requirements of VSWR and pattern in band of 100-1000MHz according the simulated result. Using the above two antennas, the ultra-short pulse radiation experiment was accomplished and transient scattering of UWB pulses by some targets of simple shapes and complex scale-models of aircraft is obtained. Finally, some research about anti-stealth is summarized. |
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