Suppression of High-Order Asymmetric Modes by Reflection Adjustment Method in Coaxial Slow Wave Structures

In the coaxial slow wave structures (SWSs) with large overmoded ratio, the high-order asymmetric quasi-TE
_v1
mode is inevitably excited. In this article, the reflection adjustment method using reflective cavity to reduce the order of the excited mode is proposed. The simulation shows that the excited mode can be changed from the quasi-TE
₅₁
mode to the quasi-TE
₁₁
mode by this method. The “mode-matching method” is used to calculate the reflection characteristics of the reflective cavity. The theoretical analysis shows that selecting the wider reflective cavity with the deeper inner cavity could make this method more effective.