Concurrent Multifrequency Complex to Real Impedance Matching Network for RF Applications

This paper presents a novel technique for matching complex loads to a real source concurrently at uncorrelated frequencies under any load conditions. In the proposed method, a branched stub adds susceptances to the load admittances such that the adjusted loads for all the frequencies can be shifted to g = 1 circle using a single series transmission line; hence matching the real part of the admittances. The left-over susceptance is cancelled through another branched stub. Its adaptability allows it to increase the number of bands by adding transmission lines to the branched stubs. The structure is not subject to any fabrication-related limitations because all the transmission lines used in the design have a characteristic impedance of 50 Ohms. The concept has been validated by designing a prototype matching network for N = 3 and extending it to N = 4, and N = 5 by adding elements to the branched stubs. All the structures are fabricated on ROGERS RO4003 substrate with a dielectric constant, er = 3.38 and height, h = 20 mils. The simulated and the measured results are in good accordance.