Design of Compact Hairpin Structure for Microstrip Bandpass Filter

Hairpin filter is one of the microwave frequency filters and it is popular because of its compact size. Hairpin filter is obtained from the edge-coupled resonator filter by folding back the ends of the resonator into a “U” shape and it does not require any grounding. A five pole hairpin resonators is designed to operate in the C-band frequency of 4.8 GHz. The hairpin filter design is carried out on different substrates like FR4, RT Duroid 6010 and RO 3010. The filter performance is compared among these different substrates and it is analyzed in terms of insertion loss and return loss.