A Compact High-Selectivity Bandpass Filter Based on Coaxial Substrate Integrated Waveguide Technology for Ku-band Satellite Communications

Abstract

This paper presents the design and simulation of a Ku-band bandpass filter based on Coaxial Substrate Integrated Waveguide (CSIW) technology for Very Small Aperture Terminal (VSAT) satellite communication systems. The core concept involves the implementation of two fundamental structures: an electric coupling type to generate a transmission zero (TZ) below the passband, and a magnetic coupling type to produce a TZ above the passband. By cascading these two structures, the resulting filter achieves two asymmetric TZs around the passband, significantly enhancing selectivity and out-of-band rejection characteristics. The design and simulations were performed using CST Studio Suite. The results demonstrate a filter with an insertion loss of less than 1.12 dB and return loss better than 15 dB within the passband, while successfully generating two TZs at 12.67 GHz and 15.55 GHz. With its compact footprint, low loss, and flexible TZ generation, the proposed CSIW filter serves as a viable solution for integration into high-power Block Up-Converters (BUCs) within VSAT systems.