COMPACT AND HIGH PERFORMANCE BANDPASS FILTER BASED ON AN IMPROVED HYBRID RESONATOR USING BEELINE COMPACT MICROSTRIP RESONATOR CELL (BCMRC)

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 0.112 lambda(g) X 0.057 lambda(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 4.05 f(0). In addition, a -20 dB rejection ultra-wide upper stopband is measured from 1.08 f(0) to 15.38 f(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.