Synthesis of Filters Comprising Cascaded Quadruplets With Both Single and Mixed Couplings

Two quadruplet configurations with both single and mixed couplings are proposed in this work and the synthesis of filters comprising cascades of these quadruplets is presented. EM implementations of two quadruplet configurations as Combline filters centered at 1 GHz achieving 5% fractional bandwidth are demonstrated. The simulated electrical performance of the EM models agrees well with their circuit counterparts.