Research And Design Of The UWB Filtering Antenna

To satisfy the trend of modern communication devices miniaturization, RF-front integrated design is becoming research highlight. Simultaneously, as a new wireless communication technology, UWB (ultra-wideband) technology has been paid a wide attention. According to the FCC's requirement, working frequency band of the UWB system is 3.1~10.6GHz. Both UWB filter and UWB antenna are the key components of UWB system. So by integrated design of UWB filter and UWB antenna, an UWB filtering antenna can be constituted, which has an essential significance to optimize the performance of UWB system..This thesis mainly concerns on analysis and design of the UWB antenna with filtering characteristic. Firstly, the thesis introduces the basic design theory of the traditional UWB filter and UWB antenna. At the same time, the limitations of traditional UWB antenna design are also pointed out in this thesis. Then, we propose that an UWB antenna with high frequency selectivity can be constituted by integrated design of UWB filter and UWB antenna. Based on the way mentioned above, several new UWB antennas fed by microstrip or CPW (CoPlanar waveguide) are designed and fabricated. On the condition of maintain passband performance, new UWB antennas all can restrain the upper-passband well. Finally, these new UWB antennas are also measured by vector network analyzer. Measured results and simulation results match well to prove advantages of the new UWB filtering antenna.The main work and the contributions in this thesis are summarized as followings:1. Based on the UWB antenna design before, an UWB antenna with good in-band and our of band characteristic is designed and fabricated firstly. This new antenna is fed by microstrip and has a compact configuration. Then, we ameliorate this UWB antenna. By inserting the lowpass filter on the antenna's feed line, highpass characteristic of the UWB antenna can combine with this lowpass filter to compose an UWB bandpass filter. By this way, we simplify the complications of the antenna. Under the premise of unidirectional radiation pattern, we optimize the out-band characteristic of the antenna. The measured results and simulation results show good agreement with each other. At last, we design an UWB antenna with a slot to restrain the upper-passband and the simulated results satisfy our requirements.2. Because of the advantages of CPW, UWB filtering antenna fed by CPW is designed by integrated with UWB filter. Based on the above, this UWB filtering antenna is ameliorated by us. By inserting lowpass configuration combined with the highpass characteristic to constitute UWB filter, we simplify the configuration, optimize out-band performance and maintain unidirectional radiation pattern of UWB antenna. We design and fabricate this new UWB filtering antenna, and its measurement results agree with the simulation results well.3. Firstly, we study the integrated design of UWB antenna and dual-band filter, which are used in dual-band communications. Then we design a new dual-band antenna with good passband isolation performance. The simulated results are nice and can fulfill our requirements.