A Generic Tri-Band Matching Network

A scheme to achieve impedance matching at three arbitrary frequencies is presented. The proposed matching network is cascade of a dual-band matching network and a novel dual-to-tri-band transformer. Analysis of the proposed network provides closed form design equations that enable physically realizable solution owing to the presence of a free design variable. The presented theory is demonstrated through two example prototypes on Roger's RO4350B substrate. The obtained simulated and measured results clearly exhibit the potential of the proposed design.