Fully Inline and Symmetric Dual-Mode Dual-Band Bandpass Filters for Millimetre-wave Applications

This work presents the design of inline dual-mode dual-band bandpass filters with flexible center-frequency allocation for application at millimetre-wave frequencies. In this design, resonators are configured for the TE101 and TM120 modes without perturbations or tuning means and allow for the control of two separate fourth-order passbands within the filter while remaining fully inline and symmetric. A presentation on the basic filter design and several examples with different center-frequency locations are presented within the W-band. A prototype with center frequencies at approximately 86.3 GHz and 100 GHz is fabricated and tested. The measurements demonstrate exceptional unloaded Q-factor results for the W-band, ultimately, validating the design approach.