Selective mode suppression in microstrip differential lines by means of electric-LC (ELC) and magnetic-LC (MLC) resonators

In this paper, it is demonstrated that the so-called electric-LC (ELC) resonators, and their dual counterparts, the magnetic-LC (MLC) resonators, are useful for the selective suppression of either the differential or the common mode in microstrip differential lines. The key point to mode suppression is the alignment of the resonator with the electric (differential mode) or magnetic (common mode) wall of the line. It is shown that by simply rotating the resonators 90° we can selectively choose the suppressed mode in the vicinity of the resonator's fundamental resonance frequency. The theory is validated through full-wave electromagnetic simulation, the lumped element equivalent circuit models of the proposed structures and experimental data. © 2013 Springer-Verlag Berlin Heidelberg.