Robust Tolerance Design of Bandpass Filter With Improved Frequency Response for Q-Band Satellite Applications

A rectangular waveguide bandpass filter for
$Q$
-band with simple fabrication is proposed in this letter. The design is based on the use of the first passband replica of commensurate-line stepped-impedance structures and achieves the suppression of their inherent low-pass response. In order to do it, the filter is implemented by rectangular waveguide sections with different widths and heights that can be analytically calculated. The technique is validated by a ninth-order Chebyshev filter with passband between 40 and 43 GHz and fabrication yield equal to 84% for a manufacturing error of
$\pm 20~\mu \text{m}$
. The measured results of the prototype fabricated with computer numerical control (CNC) milling are in good agreement with the simulated ones.