Ka-band gap waveguide coupled-resonator filter for radio link diplexers

Gap waveguide technology represents an interesting alternative as low-loss, cost-effective and high-performance transmission line and package of microwave and millimeter-wave systems. A Ka-band coupled-resonator filter for a radio link diplexer, which requires high selectivity to isolate transmit and receiving channels, is proposed and realized using gap waveguide technology. The band-pass filter, which has a central frequency of 37.37 GHz and a pass bandwidth of 560 MHz, is fabricated between two metal parallel plates leaving an air gap between them. Measurements show a minimum in-band insertion loss of 1 dB and agree quite well with simulations