A Millimeter Wave High-Order TE13 Mode Converter

In this paper a methodology to excite a circular high-order TE
₁₃
-mode via a rectangular TE
₅₀
mode was proposed and verified by the millimeter wave measurement. This topology can also be applied to launch other high-order modes (HOMs) such as TE
$_{1n}$
, TE
$_{2n^\prime }$
and TE
$_{0n^\prime }$
(n or
$n^\prime =1$
, 2, 3) modes via different transition rectangular TE
$_{m0}$
(
$m = 2n-1$
or
$m = 2n^\prime $
) modes, which can be achieved by adjusting the number of coupling apertures and optimizing dimensions of tapered waveguides. A W-band TE
₁₃
mode converter was designed and analyzed. Two identical converters connected back to back as a proof-of-principle operating at
$Q$
-band were fabricated and measured. Good performance was observed, which was in good agreement with the simulation results. This HOM converter has many potential applications in areas such as gyro-devices, high-power transmission lines, RF multimode systems of accelerators, microwave/plasma, and antenna systems.