A 3-D Printed Ka-band Twisted Waveguide Filter with Filtering and Polarization Rotation

This paper presents a Ka-band twisted bandpass filter integrated with a pair of orthogonally feed waveguides. It can achieve filtering and polarization rotation simultaneously. To validate the presented approach, a 4
^th
order bandpass filter operating at 34 GHz with 2.9% fractional bandwidth is designed and fabricated by a stereolithography-based 3-D printing process. The RF-measured results demonstrate a slight frequency shift of 0.36%, an insertion loss of 0.81 dB, and a return loss better than 15 dB.