A 3D-Printed Bent–Twisted Waveguide Filter Using Mixed TE101 and TE102 Mode Resonators

This paper presents a waveguide bandpass filter that integrates bending and twisting functions, utilizing mixed TE₁₀₁ and TE₁₀₂ mode resonators. Benefiting from the mixed utilization of TE₁₀₁ and TE₁₀₂ resonators, the desired stopband suppression and low insertion loss are achieved. To verify the feasibility of this approach, a sixth-order Chebyshev bandpass filter centered at 20.4 GHz is designed, with a bandwidth of 1.6 GHz (FBW = 7.84%) and a return loss of more than 20 dB. The filter also achieves 120° bending in the propagation direction and 90° rotation in polarization. This prototype is fabricated following the stereolithography (SLA) process using photosensitive resin, followed by metallization through electroplating to achieve a lightweight design. The measurements exhibit great consistency with the simulations.