A procedure based on the analytical model of a lumpedelement, crossover circulator has been developed to maximize its operating bandwidth. The procedure considers the circulator as a network and employs the circulation impedance - the load associated with perfect circulation - as a metric to optimize the bandwidth. Using this procedure, we find that a maximum 194% bandwidth can be obtained for an ideal circulator for any above-FMR range operation. By applying this same procedure to an actual circulator device in 225-400 MHz frequency range, we achieve a 125% bandwidth from a numerical simulation model. We have verified this result from the measurement of a fabricated device; the measured data reveals a bandwidth of 129%.
2. Konishi, Y., "New theoretical concept for wide band gyromagnetic devices," IEEE Trans. Magnetics, Vol. 8, No. 3, 505-508, 1972.
doi:10.1109/TMAG.1972.1067508
3. Anderson, L., "An analysis of broadband circulators with external tuning elements," IEEE Trans. MTT, Vol. 15, No. 1, 42-47, 1967.
doi:10.1109/TMTT.1967.1126367
4. Miura, T., M. Kobayashi, and Y. Konishi, "Optimization of a lumped element circulator based on eigenvalue evaluation and structural improvement," IEEE Trans. MTT, Vol. 44, No. 12, 2648-2654, 1996.
doi:10.1109/22.554616
5. Schloemann, E. F., "Circulators for microwave and millimeter-wave integrated circuits," Proceedings of the IEEE, Vol. 76, No. 2, 188-200, 1988.
doi:10.1109/5.4394
6. Bergman, J. O., "Equivalent circuit for a lumped-element Y circulator," IEEE Trans. MTT, Vol. 16, No. 5, 308-310, 1968.
doi:10.1109/TMTT.1968.1126677
7. Polder, D., "On the theory of ferromagnetic resonance," Phil. Mag., Vol. 40, 99-115, 1949.
8. Knerr, R. H. and C. E. Barnes, "A compact broad-band thin-film lumped element L-band circulator," IEEE Trans. MTT, Vol. 18, No. 12, 1100-1108, 1970.
doi:10.1109/TMTT.1970.1127418
9. Knerr, R. H., "An improved equivalent circuit for the thin-film lumped element circulator," IEEE Trans. MTT, Vol. 20, No. 7, 446-452, 1972.
doi:10.1109/TMTT.1972.1127784
10. Young, J. L., R. S. Adams, B. O'Neil, and C. M. Johnson, "Bandwidth optimization of an integrated microstrip circulator and antenna assembly: Part 2," IEEE Antennas and Propagation Magazine, Vol. 49, No. 1, 82-91, 2007.
doi:10.1109/MAP.2007.370984
11. Allen, J. C., Engineering and Amplifier Optimization, Birkhauser, Boston, MA, 2004.
12. Krowne, C. M. and R. E. Neidert, "Theory and numerical calculations for radially inhomogeneous circular ferrite circulators," IEEE Trans. MTT, Vol. 44, No. 3, 419-431, 1996.
doi:10.1109/22.486151
13. Young, J. L. and C. M. Johnson, "A compact, recursive trans-impedance Green's function for the inhomogeneous ferrite, microwave circulator ," IEEE Trans. MTT, Vol. 52, No. 7, 1751-1759, 2004.
doi:10.1109/TMTT.2004.830491
14. Joseph, R. I. and E. Schlomann, "Demagnetizing field in nonellipsoidal bodies," Journal of Applied Physics, Vol. 36, No. 5, 1579-1593, 1965.
doi:10.1063/1.1703091
15. Wu, Y. S. and F. J. Rosenbaum, "Wide-band operation of microstrip circulators," IEEE Trans. MTT, Vol. 22, No. 10, 849-856, 1974.
doi:10.1109/TMTT.1974.1128363
Submit
