In this paper, defected microstrip structure (DMS) is applied to design a compact microstrip rat-race hybrid coupler. The proposed structure introduces both harmonic signal suppression and a significant reduction of size because half of the ring is embedded in upper section. By embedding the DMS, it is observed that the third harmonic signal is suppressed to -25 dB with respect to a conventional rat-race hybrid coupler. Besides, this structure also effectively reduces the occupied area to 25% of the conventional case. Finally, using even and odd modes analysis the ABCD matrix of the proposed rat-race coupler was extracted. It is observed that the results are in good agreement with the full wave analysis and measurement.
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doi:10.1109/22.681209
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6. Kazerooni, M. and A. Cheldavi, "Simulation, analysis, design and applications of array defected microstrip structure (ADMS) filters using rigorously coupled multi-strip (RCMS) method," Progress In Electromagnetics Research, Vol. 63, 193-207, 2006.
doi:10.2528/PIER06052803
7. Kazerooni, M. , G. Rezai Rad, and A. Cheldavi, "Behavior study of simultaneously defected microstrip and ground structure (DMGS) in planar circuits," PIERS Proceedings, 895-900, Beijing, China, Mar. 23-27, 2009.
8. Kazerooni, M. and A. Cheldavi, "Comparing the performance of defected microstrip structures (DMS) and Defected Ground Structures (DGS) in microstrip miniature circuits," 17th ICEE, IUST, 2009.
9. Kazerooni , M., N. P. Gandji, A. Cheldavi, and M. Kamarei, "A new microwave bandstop filter using defected microstrip structure (DMS)," PIERS Proceedings, 697-700, Moscow, Russia, Aug. 18-21, 2009.
10. Kazerooni, M. , A. Cheldavi, and M. Kamarei, "Unit length parameters, transition sharpness and level of radiation in defected microstrip structure (DMS) and defected ground structure (DGS) Interconnections," Progress In Electromagnetics Research M, Vol. 10, 93-102, 2009.
doi:10.2528/PIERM09101907
11. Kazerooni, M. , M. A. Salari, A. Cheldavi, and M. Kamarei, "Analysis and modelling of novel band stop and band pass millimeter wave ¯lters using defected microstrip structure (DMS)," 1st Conf. on Millimeter-wave and Terahertz Technologies, Tehran, Iran, 2009.
12. Kazerooni, M., A. Cheldavi, M. Kamarei, "Analysis, modeling and design of cascaded defected microstrip structure (CDMS) for planar circuits," International Journal of RF and Microwave Computer-aided Engineering, Vol. 20, No. 2, John Wiley, Mar. 2010.
13. Kazerooni, M. , N. P. Gandji, A. Cheldavi, and M. Kamarei, "Harmonics blocking in the inset fed microstrip patch antenna using cascaded defected microstrip structure (CDMS)," International Journal of RF and Microwave Computer-aided Engineering, Vol. 20, No. 6, John Wiley, Nov. 2010.
14. Kazerooni , M. , M. A. Salari, A. Cheldavi, and M. Kamarei, "A very compact filter using defected microstrip structure with Island," 19th ICEE, AUT, 2011.
15. Kazerooni, M. and O. Abbas, "High isolation dual-frequency patch antenna integrated with cascade defected microstrip structure," International Journal of RF and Microwave Computer-aided Engineering, Vol. 21, No. 5, John Wiley, Sep. 2011.
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