Transmission-line analysis of a capacitively coupled microstrip-ring resonator

The resonant frequencies of a microstrip-ring resonator capacitively coupled to a feed line are accurately analyzed using a transmission-line model. By making use of ABCD- and Y-admittance matrices, a compact closed-form expression for the input impedance of the ring alone is analytically derived and shows that the ring ran be equivalently viewed as a frequency-dependent capacitor. The coupling gap is then modeled by an equivalent L-network comprising a parallel and a series gap capacitance obtained by modifying Garg and Bahl's closed-form expressions for an end-to-end microstrip gap. By simplifying the parallel and series combinations of the overall equivalent circuit, the total input impedance looking from the feed line to the gap is analytically derived to predict the resonant frequencies. To verify the analysis, the resonant frequencies of the capacitively coupled ring resonator have been accurately measured, with the experimental results showing very good agreement with the theoretical predictions.

[1]  Kai Chang,et al.  Microwave Ring Circuits and Antennas , 1996 .

[2]  P. Bernard,et al.  Measurement of dielectric constant using a microstrip ring resonator , 1991 .

[3]  D. Pozar.  Microwave Engineering , 1990 .

[4]  Kai Chang,et al.  On the Study of Microstrip Ring and Varactor-Tuned Ring Circuits , 1987 .

[5]  M. Makimoto,et al.  Varactor Tuned Bandpass Filters Using Microstrip-Line Ring Resonators , 1986, 1986 IEEE MTT-S International Microwave Symposium Digest.

[6]  P. Katehi,et al.  Frequency-Dependent Characteristics of Microstrip Discontinuities in Millimeter-Wave Integrated Circuits , 1985 .

[7]  D. Pozar,et al.  Full-Wave Analysis of Microstrip Open-End and Gap Discontinuities , 1985 .

[8]  I. Wolff,et al.  Perturbation for Open Analysis and Design Equations and Closed-Ring Microstrip Resonators , 1984 .

[9]  A. Sharma.  Spectral Domain Analysis of an Elliptic Microstrip Ring Resonator (Short Paper) , 1984 .

[10]  E. J. Denlinger,et al.  Losses of Microstrip Lines , 1980 .

[11]  K. Gupta,et al.  Microstrip Lines and Slotlines , 1979 .

[12]  B. Bhat,et al.  Spectral domain analysis of microstrip ring resonators , 1979 .

[13]  Reinhold Pregla,et al.  A Simple Method for Computing the Resonant Frequencies of Microstrip Ring Resonators , 1978 .

[14]  R. P. Owens.  Curvature effect in microstrip ring resonators , 1976 .

[15]  W.J.R. Hoefer,et al.  Evaluation of the Equivalent Circuit Parameters of Microstrip Discontiuuities through Perturbation of a Resonant Ring (Short Papers) , 1975 .

[16]  F. Rosenbaum,et al.  Mode Chart for Microstrip Ring Resonators (Short Papers) , 1973 .

[17]  P. Benedek,et al.  Equivalent Capacitances for Microstrip Gaps and Steps , 1972 .

[18]  Ingo Wolff,et al.  Microstrip ring resonator and dispersion measurement on microstrip lines , 1971 .

[19]  I. M. Stephenson,et al.  Resonant techniques for establishing the equivalent circuits of small discontinuities in microstrip , 1971 .

[20]  J. J. Hughes,et al.  Foreshortening of Microstrip Open Circuits on Alumina Substrates , 1971 .

[21]  A. Farrar,et al.  Computation of Lumped Microstrip Capacities by Matrix Methods - Rectangular Sections and End Effect (Correspondence) , 1971 .

[22]  P. Troughton,et al.  Measurement techniques in microstrip , 1969 .

[23]  P. Troughton,et al.  High Q factor resonators in microstrip , 1968 .

[24]  T.C. Edwards,et al.  Microstrip Measurements , 1982, 1982 IEEE MTT-S International Microwave Symposium Digest.

[25]  D. S. James,et al.  Microstrip end effects , 1972 .