Wideband 60 GHz bandpass filter based on flexible PerMX polymer substrate

This paper presents a wideband 60 GHz bandpass filter fabricated on flexible 50 µm-thick PerMX polymer substrate. The implemented filter is based on conventional parallel-coupled half-wavelength resonators. Thanks to the support substrate that will be finally released, the process precision can be maintained at microfabrication level. A wideband filter has been achieved through optimization of the narrow gaps between the adjacent resonators. The implemented filter shows insertion loss of 4.2 dB at the center frequency of 63.5 GHz while its return loss is better than 14 dB including two microstrip-to-CPW transitions. In addition, 3-dB bandwidth of 19 % at the center frequency of 63.5 GHz is demonstrated.