A Ka-Band Broadband Bandpass Filter with Micro-Coaxial Structure for RF Transceiver Front-End

To meet the requirements of satellite communications for higher frequency, lower loss and larger information capacity, this paper presents the design, simulation, processing and testing of a Ka-band stub bandpass filter based on a copper-based micro-coaxial structure. The designed 6th order filter has a center frequency of 28 GHz and a relative bandwidth of up to 52%. The simulation results obtained by HFSS indicate that the in-band insertion loss is better than -1 dB and the return loss is better than -15 dB. However, the test results show that the in-band insertion loss is better than -1.6 dB and the return loss is better than -10 dB. The designed filter exhibits advantage comparing the device with planar transmission line structures in Ka-band. Therefore, the designed filter is highly valuable for engineering applications.