Research Of Quad-band Bandstop Filter And UWB Bandpass Filter

Microwave filter as an indispensable field of wireless communications passive devices, who has set off a new wave in the RF microwave research field. With the WIMAX, WCDMA, WLAN, UWB and other wireless communication protocol proposed,verified, implemented and applied, this has greatly stimulated the rapid development of the filter technology. Among them, multiband and ultra-wideband filter technology has become a recent research hotspot. In this thesis, we design the microstrip filter model of the following two structures.The first filter model is a quad-band bandstop filter based on a stepped impedance square spiral resonator. By analyzing the electromagnetic properties of a unit spiral resonator with a step impedance resonance,the resonant structure of the unit is concatenated in a different form. The optimal point characteristic model, simulation and experimental results compared to other articles are designed to increase the number of bands, reduce the resonant frequency, and increase the bandwidth of each band, the insertion loss is less than 0.5dB and the selectivity has improved.The second is an ultra-wideband band-pass filter model based on open-loop resonator loading short-circuited branches. The model is constructed by using the modified form of the classical open ring as the main resonator, and the short-circuited joints are symmetrically loaded in the ring mouth, and analyzed by the odd-even mode theory to realize the ultra-wideband band-pass filter performance. The simulation results show that the filter operates from 2.1 GHz to 11.5 GHz and meets the UWB standard specified by the Federal Communications Commission (FCC). The main highlight of this design is the miniaturization of the model structure and the increase of working bandwidth.