Research Of High Performance End-fire Antennaand Bandwidth Design

End-fire antenna is an electromagnetic signal transceiver device with strong directivity,which provides a good performance radiation mode with its unique directional characteristics.Contrast with traditional omnidirectional antennas,the end-fire antenna has excellent beam orientation and easier to obtain high gain radiation properties.Therefore,it can be widely used in civil and military radio system.This thesis focuses on the end-fire antenna research and design.The main contents are as follows.(?)On the basis of microstrip principle of quasi Yagi-Uda antenna,a dual-band antenna with stepped coplanar strip and double dipole structure is proposed.The stepped slot line with different widths is used in the coplanar strapline connecting two dipoles to improve impedance match.In addition,a parasitic strip directors is added in the antenna to improve the impedance match in the high-frequency region.The simulation results are in good accordance with the experimental data,measured results show that the proposed antenna structure has a maximum gain of 4.2d Bi,it also has the desired impedance characteristics with the frequency bands of 2.91-3.85GHz and 4.77-5.02GHz.(?)A miniaturized gain-enhanced antipodal tapered slot antenna with gradual U-slot edges and dielectric lens is investigated.In order to implement the miniaturization effectively,a double U-slot edge elements is used to extend the surface current distribution of the two surfaces of the radiation aperture.Its radiation properties is improved at higher frequencies due to the use of dielectric lens.In addition,the H-plane beam has been narrowed and the improvements on main-lobe level are achieved,which contribute to the enhancement of antenna gain.Furthermore,the measured gain is 7.5–8.35d Bi in the operating frequency band of 7.85-11.8GHz.Good directivity,symmetrical radiation patterns,and compact structure make the proposed antenna suitable for integration in devices of the X-band wireless communication applications.(?)A compact broadband antipodal tapered slot antenna with a size of43×72×0.762mm~3is designed.The structure consists of four antenna elements that are fed by a 1-to-4 Wilkinson power divider.In order to reduce the mutual coupling between array elements,the defected ground structure is added in the ground plane.Then,impedance bandwidth is extended to 7-11.2GHz and the measured gain variation tends to be flat within the whole operating band,and the maximum gain can reach 12.1d Bi.Furthermore,symmetrical radiation patterns and compact structure,which makes it a good candidate for integration in the X-band wireless communication devices.