Key Specifications. Waveguide Size 1 WR-42 Waveguide Size 2 WR-42 Frequency, Min 20 GHz Frequency, Max 26.7 GHz Lowband Min Rejection 50. Highpass Waveguide Filter With WR-42 Interface Operating from 20 GHz to 26.7 GHz. The PE-W42F012 is a WR-42 highpass filter with UG Cover Flanges. The pass band is 6700 MHz, or 20 to 26.7 GHz. Implementing a waveguide design, the filter has excellent rejection of 50 dB minimum at 17 GHz, or about 3000 MHz from the band edge. It has a maximum insertion loss of 0.3 dB.