A Novel High-Efficiency Segmented Design Method for High-Power Serpentine Shaped Mode Converter

A segmented design scheme based on the iterative approach is proposed for the design of high-power serpentine shaped TM
₀₁
-TE
₁₁
mode converter. It is found that the maximum electric field strength (Emax) in a serpentine shaped mode converter is related to the power ratio of the TM
₀₁
and TE
₁₁
modes at crux positions where the two modes have phase difference of nπ. Moreover, the bending direction of the serpentine axis at the crux positions needs to be adjusted to ensure high-efficiency power conversion from TM
₀₁
to TE
₁₁
. By dividing the serpentine converter into several segments at the crux positions, and specifying the power ratio of the TM
₀₁
and TE
₁₁
modes, an improved iterative method using phase self-adaption and phase normalization is proposed for the design of the segmented serpentine structures with the desired E
_max
. For demonstration, a tri-bend TM
₀₁
-TE
₁₁
mode converter was designed at X-band for the specified E
_max
of 5 GW power input. Both the simulated and tested results of the conversion efficiency and electric field distribution are consistent with the theoretical predictions. Due to a quick estimation of the maximum power handling capacity of a serpentine shaped mode converter with arbitrary diameter, the proposed method has the merits of quick convergence and high computation efficiency.