Research On Filtering Antenna Base On Composite Right/Left-Handed Transmission Lines

Integration and miniaturization of passive devices is an important direction in the modern wireless communications. Filtering antenna has both filtering and radiating functions simultaneously, and achieves an integrated design of the filter and the antenna. However, the resonant structure of the existing filtering antennas all are based on the traditional half-wavelength or quarter-wavelength resonators, which generates large size resonators and less variety resonant modes, so the designed filtering antennas exist a variety of defects, such as large area, narrow bandwidth, etc.. To overcome these problems of filtering antenna, this dissertation in-depth studies the specific left handed material properties of the composite right/left-handed transmission line(CRLH-TL), and applies it to the design of filtering antenna, which successfully achieves the miniaturization, the ultra wideband and the multiband applications of filtering antenna. Compared to the filtering antennas with traditional resonators, the proposed filtering antennas employing CRLH-TL resonator can more effectively reduce the size and weight of the RF front-end.Main contents of this dissertation are summarized as follows:1. By using the synthetical technology of the coupling bandpass filter and establishing the equivalent circuit of the antenna, the interaction between antenna and filter is analyzed, and the co-design theory and approach of filtering antenna is proposed;2. The resonant characteristics of CRLH-TL at different boundary conditions is studied, accordingly several different resonant units with very small size and very good performance are designed;3. Based on the co-design approach of filtering antenna, the new CRLH-TL resonant units are applied to the design of filtering antenna, single-band filtering antenna, ultra wideband filtering antenna and dual band filtering antenna are designed to achieve miniaturized sizes respectively;4. All of the designed filtering antennas are verified by experiments, and the measured results are in good agreement with the simulation results.The works carried out in this thesis has certain reference value on the integration and miniaturization of wireless communications devices.