| Unidirectional radiation of UWB antennas is required in many UWB systems, so lucubration of UWB unidirectional antenna is particularly necessary to be carried out. There are special requests in time domain characteristics of the antennas in some UWB Radar system. So it is necessary to study the antennas in time domain. In brief, it is important to study the unidirectional radiation and time domain characteristics of the UWB antennas used in impulse radar system.In this paper, the related research progress on loaded ring antenna and unidirectional dipole antenna was synthesized. Lucubration of the radiation characteristics of both antennas was carried out, which indicates that the antenna of this type must work in the lower frequency band when radiating pulse signal. The time domain characteristics of the time domain antenna and the various order gaussian pulse and the spectrum distribution were summarized. For the requirements of the antenna design, a pulse generator with15-stage MARX circuit which outputs Gaussian monocycle with peak-peak width of3ns was designed. Output of Gaussian monocycle with peak-peak width of300ps can be obtained when added a capacity with appropriate capacitance in the circuit. For the specification of the borehole radar and proximity fuze radar system, solution of unidirectional planar dipole receiving antenna and unidirectional cylindrical conformal monopole antenna were proposed based on the lucubration of loaded ring antenna and unidirectional dipole antenna. A great deal of simulations by CST Microwave Studio2009was carried out. Three sets of unidirectional antennas were developed for relevant radar system. Experiments and measurements were carried to study the antennas in time and frequency domain. Through theory inferential reasoning and analysis, the conclusion was obtained that the signal amplitude received by the antenna and the distance was inversely proportional. Experiments were carried out to verify the conclusion. |
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