Research On Double Bandpass Filter Based On SIW Structure

The substrate integrated waveguide is provided with two rows of metal circular symmetry on the dielectric substrate to achieve similar rectangular waveguide with a novel microwave planar structure. Because of the distance between the metal circular hole is much smaller than the wavelength, the energy of the leakage of the adjacent hole gap is very small. It combines the characteristics of the two aspects of the rectangular waveguide and the microstrip transmission line, with high quality factor, high power capacity, radiation loss, easy processing and integration etc. Widely used in microwave circuits such as filters, couplers, antennas, power divider, oscillators, etc.The main purpose of this paper is to study the design of bandpass filter based on substrate integrated waveguide structure, the SIW structure combines with complementary split ring resonator to design a dual band bandpass filter, the filter has a good pass band return loss and out of band rejection. The main work is as follows:1. This paper introduces the basic performance parameters and design of the filter theory, and in order to reduce substrate integrated waveguide and other microwave planar circuits connection impedance mismatch caused by the reflection and power loss, design a substrate integrated waveguide and microstrip line impedance matching connector.2. Based on the structure of the substrate integrated waveguide, a single pass band filter is designed by introducing the complementary split ring structure. The central frequency of the filter is 3.5GHz, and the return loss is 20dB, and the band rejection is 60dB, which has good band rejection and frequency selectivity. The influence of the size parameters of the complementary split ring resonators on the transmission passband of the filter is also analyzed.3. Through the introduction of two sets of different size parameters of the complementary split ring resonator structure design of a dual band filter, in the case of the same area to achieve the dual passband characteristics. The central frequency of the filter is 2.4GHz and 3.5GHz, and the return loss is up to 25dB, and the band rejection is up to 70dB, which has good passband inner return loss and out of band rejection. The measured results are in good agreement with the simulation results, which proves the superiority of the structure.