Miniaturization Of Waveguide Filters On H-plane Stacked Substrates

With the development of modern science and technology,the realistic scenario puts forward higher technical requirements for the communication system,but due to the limited spectrum resources,the modern communication system can only strive to improve the performance of the filter to achieve higher spectrum utilization,in order to meet the needs of complex scenarios.Waveguide filters have been widely used in satellite and radar systems owing to their high-power capacity,high reliability,and high Q.However,their large size has been a major constraint to their further application,and researchers have made great efforts to miniaturize waveguide filters.To address this situation,a miniaturized waveguide dual-band bandpass filter is designed with the design band in the X-band,and it is planned to implement the dual-band by introducing a rejection band in the wide pass band.First of all,this paper analyzes the filtering principle based on the E-plane waveguide filter,and designs an improved H-plane Split Ring Resonator(SRR)structure band-stop filter.This filter not only has good stop band performance,but also has strong tunable characteristics,and its size is smaller than that of the E-plane filter.The Complementary Split Ring Resonator(CSRR)structure and asymmetric gap resonators are then combined in this paper,etched onto the front and back copper layers of the dielectric substrate,and two transmission zeros are introduced on the upper and lower sides of the transmission poles,respectively,to form a wide passband filter.An improved SRR filter is combined to form a miniaturized H-plane stacked dual-band bandpass waveguide filter.The filter has a wide passband,high isolation between the passbands and adjustable band position.In view of the difficulties of processing and testing the stacked filter,this paper compresses their volume by changing their structure to form a single-layer two CSRR structure filter,and a single-layer three CSRR structure dual-band bandpass filter is proposed to improve the rectangle coefficient of the low-frequency passband of the single-layer two CSRR filter.The filter sacrifices tunable characteristics,but it has a higher rectangle coefficient,better pass-band isolation and better out-of-band rejection.Moreover,compared with existing waveguide filters,the filter volume proposed in this paper has been reduced by more than 2/3,while ensuring a basically consistent bandwidth.Finally,this paper introduces varactor diodes into the filter to design tunable filters and proposes a SIW-like structure to ensure the smooth fabrication of varactor diode tunable waveguide filters.