Design of compact coaxial waveguide TE21 mode coupler

Abstract

This paper proposes a compact Ku band TE21 mode coupler based on coaxial waveguide. This compact coupler takes only half the length of conventional circular waveguide coupler while maintains at least 55dB rejection of unwanted modes and reaches -6.3dB coupling to each of the rectangular waveguide arms in a bandwidth of 700MHz. The coupler can miniaturise the total length of monopulse system which utilizing TE21 mode for self-tracking.