Design and Verification of Broadband Substrate Integrated Waveguide TE₁₀-TE₃₀-Mode Converter

A broadband TE10-TE30-mode converter is designed and implemented using the substrate integrated waveguide (SIW) technique, which can generate a single TE30-mode guided wave with a high conversion efficiency. The proposed SIW converter is comprised of a 1-to-3 power divider, a three-way phase shifter, and a TE30-mode combiner in sequence. The power divider distributes the input TE10-mode guided wave into three subsections with equal amplitudes. By adopting a self-compensating phase-shifting scheme, the three-way phase shifter can modulate the phase of the TE10-mode guided wave in each subsection to achieve alternating phase reversals, mimicking the propagation property of TE30 mode. The output of the three-way phase shifter can jointly compose into a single TE30-mode in the TE30-mode combiner. The TE30-mode propagation property is analyzed to verify the mode conversion through either simulations or experiments, and good agreements are achieved. The results show that the obtained TE30-mode guided wave can be propagated in a single-mode manner over a broad bandwidth of 11.28-14.8 GHz (27%) with both a conversion efficiency and a mode purity greater than 95%. The proposed mode converter is promising for planar integration with microwave and millimeter-wave circuits.