A novel microstrip lowpass filter (LPF) with very sharp roll-off, compact size and ultra-wide stopband ispresented in this paper. The structure consists of modified stepped impedance Hairpin resonator and acircular patch as a suppressor. The proposed LPF has the cut-off frequency of 1.07 GHz. The simulationresults indicated that the transition-band of the proposed LPF is 0.09 GHz from −3 to −20 dB. Maximuminsertion-loss at about 80% of the passband is 0.1 dB. The proposed LPF has been designed, fabricatedand measured. From the measurements, good agreements with the simulated results are obtained. Also,an ultra-wide stopband was achieved. Proposed LPF has an ultra high figure-of-merit (FOM) of 151,523,which shows its strong efficiency.
