| Beased on the needs of research projects and practical applications,thie dissertation focuses on the miniaturized and broadband design airborne ultrashort-wave antenna,and the design of pulse ultra-wideband antennas.The main novelty works by the author are summarized as follows:Firstly,an ultra-wideband and minizturized airborne ultrashort-wave antenna is designed.A blade monopole antenna with double-exponential tapered end is innovatively designed to expand the bandwidth.The radiating structure of the blade monopole antenna adopts a half-cut design,a gradient design,a truncated design,and a loading design.In order to expand the bandwidth of the antenna at low frequencies,a broadband matching network is designed,which is loaded between the feed structure and the radiator structure.The antenna achieves an impedance bandwidth of 185.5%(30-800 MHz),covering the VHF band.The radiation patterns on the horizontal plane show an omnidirectional radiation for the antenna.The maximum gain is 5.6 dBi at 800 MHz,and in the 150-800 MHz range,the gain is greater than 0 dBi.The performance of the antenna meets the requirements of the index?Secondly,a tapered slot pulse ultra-wideband antenna is designed.A novel feed structure based on the transmission line model is designed using the slotline and the CPW transmission line.The novel feed structure generates an electric field distribution with balanced odd mode,then realizes an unbalanced-balanced feed structure.The feed structure has better ultra-wideband characteristics.The tapered slot pulse antenna achieves an impedance bandwidth of 142%,maintains stable end-fire radiation characteristics and flat gain,and the group delay curve remains relatively flat and achieves small signal distortion.The antenna has good frequency domain characteristics and time domain characteristics,and meets the requirements of pulse ultra-wideband systems.Thirdly,a tapered slot pulse ultra-wideband filter antenna is designed.Firstly,a microstrip transmission line with low-pass filtering characteristics is designed independently based on the stepped impedance resonator.Then the integrated design of the antenna and filter improves the band-edge selectivity of the antenna at high frequencies.The ratio of the-3 dB bandwidth to the-10 dB bandwidth of the antenna is 1.07,which is very close to 1.The proposed has a good rectangular coefficient.The results of frequency domain and time domain parameters prove that the antenna has a good out-of-band suppression and band-edge selectivity,and tne antenna has excellent pulse signal processing capabilities.Finally,a miniaturized tapered slot pulse ultra-wideband antenna is designed.Based on the new feed structure,a power division network is designed using two slotlines with phase change and four parallel slotlines.The design of the feeding structure based on the traveling-wave working mode is realized,which effectively shortens the size of the tapered slot along the slot opening direction.The measure results show that the antenna with a compact structure with a volume of 13.8×30×0.762mm3(0.12×0.26×0.006?03,which ?0 is the free-space wavelength at the lowest operating frequency),the antenna obtains more than 142%impedance bandwidth.The antenna maintains good end-fire radiation performance and flat gain.The group delay curve obtained by the test is kept flat,and a small signal distortion is achieved.The above research results show that the antenna has good frequency and time domain characteristics and can be a good candidate for pulse ultra-wideband system equipment. |
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