Electroformed Dual-Mode Waveguide Filter With No Tuning Screws

This letter presents an X -band dual-mode rectangular waveguide resonator filter with transmission zeros fabricated by electroforming. The reason for employing electroforming in filter fabrication is that the rectangular waveguide resonators can avoid having rounded corners that are inevitable for filters fabricated by a commonly used method, milling. Having no rounded corners enables fast and accurate design supported by electromagnetic simulations. Hence, the fabricated filter produces a frequency response that agrees well with the simulated response although the filter employs the dual-mode technique and there are no tuning screws at all for fine-tuning the resonant frequency of each resonator and the coupling values.