Microwave Measurement of a Compact Circular TE11 Mode Coupler Loaded With Ridges

Design and microwave measurement of a linearly polarized circular TE
₁₁
mode coupler are reported in this article. Based on our earlier designed input coupler with smooth wall, we proposed an improved structure with ridges loading resulting in a bandwidth up to 29.2%. Simulation results show the port reflection
${S}_{11}$
less than −10 dB is in 7.9–10.6 GHz. And the split transmission
${S}_{21}$
and
$S_{31}$
are over −3.4 dB in this frequency range. According to the simulation results, the designed input coupler is fabricated and measured with the vector network analyzer. The measurement results show excellent performance, which is in good agreement with the simulation when the conductor loss is taken into consideration. In addition, an input coupler with a cutoff waveguide is designed to improve the efficiency of single-port transmission and the power utilization. Simulation results show the transmission efficiency of the single port achieves 91%.