SPURIOUS RESPONSE SUPPRESSION IN HAIRPIN FILTER USING DMS INTEGRATED IN FILTER STRUCTURE

In this paper, several Defected Microstrip Structure (DMS) are used to suppress the flrst and second spurious responses in microstrip hairpin fllters. The DMSs are integrated in fllter structure, and therefore this method keeps the fllter size unchanged. The DMS interconnection disturbs the current distribution only across the strip, thereby giving a modifled microstrip line with certain stop band. The undesired spurious harmonics are suppressed through multiple transmission zeros which are added at these frequencies by designed DMSs. Experimental results verify that 25dB suppression for the flrst harmonic and 40dB suppression for the second harmonic, respectively, without afiecting the main passband response. There is a good agreement between the simulated and measured results.