Studies On Broadband And High Gain Planar Microstrip Array Antenna

Planar antenna with high gain and wide bandwidth has always been highly required in various civilian and military applications,like modern communication,radar and electronic warfare.For example,in the millimeter wave systems,such antennas will have better performance in anti-fading and improving the stability of the transmission link;also,the spectrum resource in millimeter wave demands a wideband or even ultra-wideband antenna;as another example,the onboard antennas in moving carriers like plane,ship and satellite are tend to be integrated into a shared aperture to relieves the antenna load and reduce the RCS.However,the antenna gains and bandwidths may be influenced due to mutual coupling.Hence,improving the gain and bandwidth of antennas in a shared aperture will have a significant meaning in system performance.In response to these urgent needs,the thesis begins with a study on the design of microstrip antenna array in millimeter wave.The antenna element adopts the multi-layer substrate patch structure,and the array is fed by a S-like microstrip line feed network.The feed network is optimized to effectively improve the feeding efficiency,hence the antenna array has a high gain.The measured results of the fabricated 4×4 elements array showed that,the band width of S₁₁<-10dB and AR<3dB is 40%and11.43%,respectively,the maxim gain is 17.8dBic.Then,using the microstrip patch antenna,the design of shared aperture antenna is studied.As the cavity mode analysis shows,the radiation of the patch mainly comes from the slots between the patch and the ground,which means cutting slots on the radiator will have less effect on the antenna's performance.Based on the analysis,a S/X dual band antenna and a S/Ku band antenna element are designed.The measured bandwidth of S₁₁<-10dB in S,X band is 29.6%and 17%,respectively.And then,combined with a dual polarization microstrip patch antenna array and a reconfigurable feed network,a 4×4 element array is designed.The antenna has a high gain and can be switch to work in horizontal/vertical and left/right hand circularly polarized modes.the measured S₁₁<-10dB bandwidths of these four modes are 14.9%?15.1%?20.4%and 20.2%.Finally,a conclusion is given.The design antenna array are utilizable in various application,the design method is constructive in future high gain wide band planar antenna designs.