220 Ghz Wideband Bandpass Filter Using Stepped Impedance Resonators

Superconducting Transition-Edge Sensor (TES) detectors play a pivotal role in detecting Cosmic Microwave Background (CMB) radiation, with bandpass filters being an essential component of these systems. This paper presents the design of a fifth-order microstrip bandpass filter based on stepped impedance resonators. The filter's S-parameters were simulated and analyzed using HFSS electromagnetic simulation software. The results demonstrate a 3 dB bandwidth of 62 GHz, a fractional bandwidth of 28 %, a return loss exceeding 18 dB, and a shape factor of $\mathbf{0. 7 1}$. These performance characteristics significantly surpass those of conventional third-order comb-line bandpass filters used in TES systems.