Filter Antenna Design And Its Application Research

Along with the development of communication and information technology,electronic systems with low power consumption,integration and multi-functional become a developing trend.As a consequence,microwave energy harvesting systems and multi-functional shared-aperture antennas become research hotspots.Meanwhile,the filtering antenna has been widely concerned as an integrated design of antennas and filters.In this thesis,the design of the filtering antennas is researched,as well as the applications in rectifying antennas for the microwave energy harvesting system and the dual frequency dual circular polarization shared-aperture antenna for the satellite communication system.Main studies in this paper have been given as follows.Firstly,the research status of the filtering antennas is described in the related application.The design on filtering antennas and two compact filters,compact micro-strip resonant cell(CMRC)filter and step-impedance ring resonator filter are discussed for specific applications.Secondly,a broadband rectifying antenna is proposed with a working band from 2.3GHz to 2.6GHz for the microwave energy harvesting systems.It adopts a broadband filtering antenna with harmonic rejection property as a receiving antenna,which consists of a CMRC filter and a multi-layer U-slot micro-strip antenna.Simulation results show that the return loss is less than that 0.1 dB at the 2nd and the 3rd harmonic frequencies.By utilizing the rectifying diode for low input power and a micro-trip matching circuit,a broadband rectifier circuit has been designed with stable rectifier efficiencies.Thirdly,dual-band dual circularly-polarized(CP)micro-strip arrays have been developed with a single-layer substrate,by utilizing filtering antenna elements to improve the isolation between two arrays with different frequencies and polarizations.The filtering antenna elements are designed with a miniaturized sharp-rejection filter and a CP micro-strip patch to achieve the sharp-rejection property.Then two filtering antenna elements with different frequencies and polarizations can be integrated together through a microstrip-line diplexer to implement a dual-band dual CP antenna unit.Therefore the dual-band dual CP arrays can be implemented with those dual-band dual CP antenna units which are fed through single corporate fed network.Filtering antenna elements effectively improve the isolation between the different frequency patches so that the operating frequency(8.6GHz/8.2GHz)ratio of the two element can be reduced to 1.04.The 16-and 64-elements arrays have been developed.Measured results show that good CP radiation and low cross-polarization performance have been achieved at two operating frequencies.The proposed dual-band dual CP array has broad application prospects,due to the fabrication convenience for the single-layer substrate structure,and the good scalability for constructing larger arrays.In this thesis,the design of the filtering antennas is studied for the microwave energy harvesting system and the shared-aperture antenna.A broadband rectifying antenna and the dual-band dual circularly-polarized micro-strip arrays have been successfully developed for specific applications,which have good engineering application values.