Design of Miniaturized Multiband Substrate Integrated Waveguide Filters

Multi-band filters are crucial for enabling the transmission of multiple signals simultaneously in modern communication systems. However, there is a lack of multi-band filters with small size, easy integration and superior filtering performance, so in this paper, we propose a design method for multi-band substrate integrated waveguide filters that overcomes these challenges. Combining the design methods of single-band and dual-band filters with substrate integrated waveguide resonators can increase the number of passbands without increasing the physical size of the filter. In theory, bandpass filters with arbitrary passbands can be designed in a specified order. As an example, the corresponding dual-band filter and triple-band filter are designed for verification in this paper. The simulation results show that the filter exhibits sharp out-of-band rejection, a compact structure, and a return loss less than -20dB, indicating excellent filtering characteristics, but the required physical size is the same as that of a single-band filter. The measurement results coincide with the simulation results, indicating the feasibility of the proposed method.