An Equation-based Method for the Design of End Couplings in Combline Microwave Cavity Filters

The manuscript presents an equation-based method for achieving the desired end coupling in combline microwave cavity filters. The equations are based on the formula for the resonant frequency of a lumped
$LC$
circuit and a simple relationship between the external quality factor and the height of the pin feeding the end resonator. The algorithm is tested on a combline microwave cavity filter for the E1 Galileo band.