A Miniaturized Harmonic Reject Waveguide Filter for Ku-Band VSAT Transmitter

In this paper, a novel miniaturized low-pass waveguide filter with wide stop-band is proposed for the harmonic rejection of Ku-band Very Small Aperture Terminal (VSAT) transmitters. The consists corrugated and metal septum in $H$ -plane at center narrow side wall. Because it does not require additional impedance transformers, achieves compact size. To estimate amplitude level higher-order modes input port reject RF transmitter, generated by notation="LaTeX">$E$ probe-type microstrip-to-waveguide (M2W) transition are analyzed calculated using commercial numerical tools. analyze response modes, mode conversions structure also calculated. analysis shows that free spurious all can be obtained co-designing M2W filter. validate design concept, designed WR-75 waveguide. Simulation results show reflection less than −23dB between 13 notation="LaTeX">$\sim $ 15 GHz, while suppression performance TE 10 better 35dB 17.5 29.6 GHz. effective length 29 mm. indicate pass-band 20, 21 TM improved transition. Finally, to idea, GaN power amplifier fabricated measured. measurements has minimum output 72.5 W 20 dBc notation="LaTeX">$2^{nd}$ rejection. By filter, measured greater 52 dBc.