Conception and realization of highly selective band-pass filters in Ka-band built on thin polymer films

A novel structure of high performance narrow band-pass filters on thin polymer film is reported in this paper. It's composed of two microstrip resonators placed between two via-free microstrip-grounded coplanar waveguide transitions. It combines therefore compactness, low-cost, fabrication easiness of microstrip lines and connection facility of coplanar pads. Narrow band-pass filters have been optimized by using HFSS software, realized and characterized, over the range of Ka-band frequencies. With the band-pass filter realized on thin BCB polymer (benzocyclobutene, relative permittivity er = 2.65 and loss tangent tanô = 0.0025) film of 60 μm thick, the performance obtained for a center frequency optimized at 30.5 GHz is 28.8 for quality factor and −1.4 dB for insertion losses, with very good agreement between simulation and experiment results.