Compact and High Performance Bandpass Filter Based on an Improved Hybrid Resonator Using Beeline Compact Microstrip Resonator Cell (BCMRC)

Abstract

In this paper, a compact microstrip bandpass filter is presented by using a proposed improved hybrid resonator. Without requiring the cross-coupling and the source-load coupling, the new filter has a transmission zero on the upper stopband to provide a high selectivity. The fabricated filter is designed at f ₀ = 1 GHz and has a compact size of 0.112λ_g×0.057λ_g. Good agreement is observed between the measurements and simulations. The measured results show that the new filter has a wide −60 dB rejection upper stopband from 1.24f ₀ to 4.05f ₀. In addition, a −20 dB rejection ultra-wide upper stopband is measured from 1.08f ₀ to 15.38f ₀. The new filter can be fabricated using the standard printed-circuit-board (PCB) process and has a planar topology, which is easily integrated with the modern wireless communication system.