Research On Miniaturized Wide-band Filtenna For Radio Frequency End

Nowadays,the design concept of multi-functional device provides a new idea for the miniaturization of microwave devices.The design of filtenna that integrates antenna with filter greatly reduces the size of the radio frequency(RF)front-end and improves the filtering performance.The rapid development of communication requires a large number of wide-band devices to provide high-rate multimedia transmission.In this thesis,the integrated design theory of the filtenna and the design method of the wide-band filtenna based on multi-mode resonator are studied in detail.The research on the miniaturization of the wide-band filtenna has also been conducted.The main research content includes the following four parts:Firstly,Stub-loaded ring resonator(SLRR)with two types of short-circuited point is proposed.The resonator has different frequency response and harmonic characteristics under different short-circuited points.By analyzing the resonant mechanism of the proposed resonator,analytical expression between the resonant mode and the electrical length is obtained.Furthermore,based on the SLRR with short-circuited point at the ring edge,a coplanar waveguide(CPW)high temperature superconducting(HTS)dual-band band-pass filter(BPF)is designed and fabricated.The circuit exhibits excellent characteristics such as small size(0.146?_g×0.083?_g)and low insertion loss(0.15 dB),which proves the superiority of the short-circuited SLRR in design of the microwave circuit.Secondly,a resonator-coupled wide-band filtenna is proposed based on the short-circuited SLRR,the design method of a wide-band filtenna for multi-order resonant circuits is studied.Based on the integrated design theory of resonator coupled filter,the antenna element is equivalently replaced by the last-order resonant circuit and the load of the filter,so that it acts as both a radiator and a resonator of the filter.The equivalent process and parameter extraction method of the antenna are analyzed in detail.As a demonstation,a compact third-order wide-band filtenna(circuit size 0.26?_g×0.27?_g,fractional bandwidth 11.6%)was designed and fabricated.The measured results show that the gain of the filtenna exhibits filtering characteristic and out-of-band rejection characteristic(about triple fundamental frequency bandwidth).Thirdly,the filtenna based on slot-line resonator is studied.The filtenna consists of two hairpin type slot-line resonators and a monopole antenna.The energy is fed to the slot-line resonator through the microstrip and then coupled to the monopole antenna.The designed filtenna exhibits filtering characteristic and compact size(0.231?_g×0.296?_g).Finally,the design method of a wide-band filtenna based on three-mode resonators is studied.A wide-band filtenna is designed using symmetrical stub-loaded microstrip three-mode resonator.By analyzing the resonant mechanism of the proposed resonator,the analytical expression between the resonant mode and the electrical length is obtained.The wide-band filtenna is achieved by adjust the frequency distribution and coupling of the resonator,which has fractional bandwidth of 16.1%and compact size(0.51?_g×0.30?_g).