Experimental study of L-band metallic photonic crystal TEM-TE₁₁ mode converter

A metallic photonic crystal TEM-TE11 mode converter is designed and its testing results are presented. Simulation results show that its conversion efficiency is above 99% at the center frequency of 1.31 GHz. In the frequency range of 1.27-1.376 GHz, the conversion efficiency exceeds 90%, with a corresponding bandwidth of 8.1%. A TEM mode excitation and a horn antenna are fabricated to test the performance of the mode converter. The mode converter is also tested with a magnetically insulated transmission line oscillator (MILO) tube. The whole device works well. The photonic TEM-TE11 mode converter is capable of handling GW level high power microwave. The measured radiation patterns of the mode converter agree well with the simulated results, indicating that the simulated results are valid.