Filtering Antenna Design In Wireless Communication

Nowadays wireless communication equipments demand low power, multi-function, miniaturizationand integration. Antenna and filter are usually cascaded in wireless communication systems. It is paidmore attention to individual devices in the traditional design methods. In this case, impedancemismatching will be caused when they are directly cascaded. It is desired to remove the limitation ofstandard terminal impedance and integrate the antenna and filter into a single module which is calledfiltering antenna. It can achieve filtering and radiating functions simultaneously as well as reduce thedimensions and weight of RF front end effectively.The main work and contributions in this thesis can be summarized as follows:1. A microstrip end-fire filtering antenna is designed based on the quasi-Yagi antenna and balunbandpass filter. It can effectively reduce circuit size without using extra balun structure.2. An end-fire filtering antenna is designed based on substrate integrated waveguide (SIW)structure. Good impedance matching can be realized by adjusting the coupling structure between theantenna and filter. The presented filtering antenna effectively suppresses unwanted signals out of theband.3. A UWB filtering antenna with dual band-notched performance is designed. It can realize notchedperformance and effectively suppress the high frequency band radiation simultaneously.4. A printed monopole filtering antenna with hairpin resonators is designed using filter synthesisapproach. Here, an antenna performs not only a radiator but also the last resonator of the bandpassfilter. The design of this filtering antenna realizes the integration and miniaturization for filter andantenna. From the simulation and measured results, the filtering antenna return loss and gain curve aresimilar to the filter return loss and insertion loss curve. This shows that filtering antenna can achievethe antenna and filter function simultaneously.5. A novel high isolation and wide upper-stopband microstrip diplexer for GSM and WLANapplication is designed through the combination of two compact filters with SCSIRs. Further,dual-frequency antenna and duplexer are integrated design and effectively reduce the size of the RFfront end in dual frequency communication system.