Novel compact narrow-band band- pass filter (NB BPF) using microstrip closed- loop ring resonators for personal communication systems (PCS´s)

In this paper, a novel compact elliptic-function narrow-band band-pass filter is developed using a new configuration of coupled lines to further enhance the coupling strength at the input and output terminals. It is shown that this proposed model provides an effective and beneficial flexibility to control the performance of the filter to realize a narrow-band band-pass filter with improvement in insertion and return losses as well as 3-dB bandwidth less than 2%. The proposed NB band-pass filter is designed and simulated on a 50-mil-thichness substrate with a dielectric constant of 10.5.