Effect of Wall Thicknesses on Broadband Design of Ka-Band TE_(21)-Mode Coupler

Commonly,the classical formulas are suitable for designing the TE21-mode coupler for the operating frequency under Ka-band by ignoring the wall thickness.However,in practice,for the one operated in the Ka-band,such classical formulas are not valid and the effect of wall thicknesses should be considered.Herein,we propose a design method for the Ka-band TE21-mode coupler via computer simulations,taking into account the wall thickness.The experimental results show that using the linear twice-weighted algorithm to optimize the coupling hole size can improve the coupler performance.And the bandwidth of such coupler increases by 10%with lower coupling loss(<0.5 dB)and higher isolation(>40 dB).