Investigation Of Pulse Antenna, UWB Antenna And Their Arrays

Carrier free pulse technology and ultra-wideband(UWB) technology have been widely used in target recognition,imaging,anti-stealth technique,anti-interference and UWB communication.The antenna,as one of the key components of the pulse and UWB systems,has drawn more and more attention,and becomes a hot topic.In this dissertation,the research is carried on the pulse antenna,the UWB antenna and their array.It is mainly focused on the time-domain characteristics of pulse antenna array, design of compact UWB antennas,and design on planar UWB antenna array.The main work and the innovation points are:1.Using current at integer time moment to approximate current at noninteger time moment will cause accumulation error and lead to instability in late time,when march-in on time(MOT) method is applied to solving time domain integral equation.For this problem,a modified MOT is proposed,in which the current at noninteger time moment is interpolated by two near currents at integer time moments.Therefore,the accumulation error is reduced significantly,and instability property of the MOT is improved efficiently.2.The definition of relative coupling current and relative coupling far field are proposed to study the mutual coupling between the elements of the pulse antenna array.The mutual coupling effect of the elements,the relationships between time-domain radiation characteristics and parameters of the array structure,and the scan capability of the array are studied by the modified MOT.3.A circular slot UWB antenna with annular ground ring is proposed.The ground annulus of the antenna plays not only as a ground but also as one part of the radiation element of the antenna.This design reduced the size of the antenna. Simulated and measured results show that the impedance bandwidth of this antenna can cover 3.1-10.6 GHz UWB frequency band.Meanwhile,the fidelity of the signal radiated by the antenna can meet the demand of UWB system within a large space scope.4.A dual open-annulus antenna that can be applied in UWB system is proposed base on the former circular slot antenna.The radiation patch and the ground of the antenna are all open struct-ures.Conductor can be placed in the hole of the radiation patch and the open region of the ground annulus without significant effect on antenna performance.This provides the possibility of integrating circuit components inside of the antenna,and makes the system more integrative.5.The design method of the microstrip feeding network of planar UWB antenna array is given.Tapered microstrip lines are used to realize the impedance transform within UWB frequency band.Three prototypes of 4-element UWB antenna array are designed and fabricated,and the influences of the coupling effect within the array on the radiation characteristics are studied.Simulated and measured results show that the bandwidths of these three prototypes antenna arrays can cover the UWB frequency band.The directivity and the gain are enhanced.The fidelity in the main radiating direction can meet the demand of UWB system.6.The design method of the CPW feeding network with tapered CPW lines for planar UWB antenna array is put forward.Three prototypes of antenna array fed by this kind of networks are designed.The influences of the coupling effect in the array on the radiation characteristics are studied.Simulated results show that the directivity and the gain of the array are improved.