X-BAND MINIATURIZED WIDEBAND BANDPASS FILTER UTILIZING MULTILAYERED MICROSTRIP HAIRPIN RESONATOR

This paper presents a new design of miniaturized wideband bandpass fllter using microstrip hairpin in multilayer conflguration for X-band application. The strong coupling required for wideband fllter is realized by arranging flve hairpin resonators in two layers on difierent dielectric substrates. Since adjacent resonator lines are placed at difierent levels, there are two possible ways to change coupling strength by varying the overlapping gap between two resonators; vertically and horizontally. In this paper, simulated and measured result for a wideband fllter of 4.4GHz bandwidth at 10.2GHz center frequency with flfth order Chebyshev response is proposed. The fllter is fabricated on 0.254mm thickness R/T Duroid 6010 and R/T Duroid 5880 with dielectric constant 10.2 and 2.2 respectively using standard photolithography technique. Two fllter conflgurations based on vertical (Type 1) and horizontal (Type 2) coupling variation to optimize the coupling strength are presented and compared. Both conflgurations produce very small and compact fllter size, at 5:0 £ 14:6mm 2 and 3:2 £ 16:1mm 2 for the flrst and second proposed fllter type respectively. The measured passband insertion losses for both fllters are less than 2.3dB and the passband return loss is better than i16dB for fllter Type 1 and i13dB for fllter Type 2. Very small and compact fllter is achieved where measured results show good agreement with the simulated responses.