In this paper, a compact microstrip low-pass filter with elliptic-function response is presented. A halfring along with two half-elliptic patch resonators is cascaded to design a compact low-pass filter with very wide stop band and high selectivity in a small circuit area. This filter has the stop band from 3.3 up to 27.57 GHz with attenuation level better than -20 dB. The proposed filter has low insertion loss in the pass band and stop band, high return loss (RL), and very wide rejection in the stop band, along with compact size and simple configuration .The filter is designed, fabricated and measured. Simulation and measurement results are presented and compared to previous researches. The results of simulations and measurements are in agreement.
