Electromagnetically coupled microstrip square/circular ring resonators: inset/offset feed variation effects on resonance frequency

Inset/offset feed-dependent variation of electromagnetically coupled microstrip square and circular ring resonators (MSRR/ MCRR) over a wide range indicate overall increase and decrease in resonant frequency (f(r)) respectively. On the basis of the experimental results, equations are suggested to determine fr as a function of the normalized inset and offset feed positions. Equations are validated for a limited range. High values of quality factor Q = 618 are obtained with MSRR as compared with MCRR (Q = 375) at two offset points near the ring edge with VSWR approximate to 1. This advantage can be used for applications such as frequency-selective circuits and sensors. (C) 2007 Wiley Periodicals, Inc.