Iris type waveguide to cavity couplers are used to couple power to particle accelerator cavities. Waveguide to cavity coupling for arbitrarily oriented rectangular iris is analyzed using Bethe's small hole coupling theory. Magnetic moment of rotated iris is obtained by defining its dyadic magnetic polarizability. Power radiated by magnetic moment into the incoming waveguide is used for coupling calculations at arbitrary angle. A close agreement is found between the proposed theory, simulations and microwave measurements.
2. Cohn, S. B., "Determination of aperture parameters by electrolytic-tank measurements," Proceedings of the IRE, Vol. 66, 1416-1421, Nov. 1951.
3. Gao, J., "Analytical formula for the coupling coefficient β of a cavity-waveguide coupled system," Nuclear Instruments and Methods, Vol. A309, 5-10, 1991.
4. Gao, J., "Analytical determination of the coupling coefficient of waveguide cavity coupling systems," Nuclear Instruments and Methods, Vol. A481, 36-42, 2002.
5. Kumar, R., "A novel method for variable coupling using iris rotation in RF couplers," Nuclear Instruments and Methods, Vol. A600, 534-537, 2009.
6. Balleyguier, P. and M. Painchault, "Design of RF power input ports for IPHI RFQ," Proc. European Particle Accelerator Conf. EPAC, 2124, Paris, 2002.
7. Balleyguier, P., "External Q studies for APT cavity couplers," Proc. Linear Accelerator Conf. LINAC, 133-135, Chicago, 1998.
8. Kamigaito, O., "Circuit model representation of external-Q calculation," Phys. Rev. ST Accl. Beams, Vol. 9, 062003, 2006.
9. Rengarajan, S. R., "Analysis of a centered-inclined waveguide slot coupler," IEEE Trans. Microwave Theory Tech., Vol. 37, No. 5, 884-889, May 1989.
10. Rengarajan, S. R., "Characteristics of a longitudional/transverse coupling slot in crossed rectangular waveguides," IEEE Trans. Microwave Theory Tech., Vol. 37, No. 8, 1171-1177, Aug. 1989.
11. Nesterenko, , M. V., V. A. Katrich, Y. M. Penkin, S. L. Berdnik, "Analytical methods in theory of slot-hole coupling of electrodynamic volumes," Progress In Electromagnetics Research, Vol. 70, 79-174, 2007.
12. Accatino, L., G. Bertin, and M. Mongiardo, "A four pole dual mode elliptic filter realized in circular cavity," IEEE Trans. Microwave Theory Tech., Vol. 44, No. 12, 2680-2687, Dec. 1996.
13. Khan, Z. A., C. F. Bunting, and M. D. Deshpande, "Shielding effectiveness of metallic enclosures at oblique and arbitrary polarizations," IEEE Trans. Electromagnetic Compatibility, Vol. 47, No. 1, 112-122, Feb. 2005.
14. Saito, Y. and D. S. Filipovic, "Analysis and design of monolithic rectangular coaxial lines for minimum coupling," IEEE Trans. Microwave Theory Tech., Vol. 55, No. 12, 2521-2530, Dec. 2007.
15. Collins, R. E., Field Theory of Guided Waves, IEEE Press, 1996.
16. Mongia, R. K. and R. K. Arora, "Equivalent circuit parameters of an aperture coupled open resonator cavity," IEEE Trans. Microwave Theory Tech., Vol. 41, No. 8, 1245-1250, Aug. 1993.
17. Roy, R. and O. Shanker, "Calculation of inter cavity coupling coefficient for side coupled standing wave linear accelerator," IEEE Trans. Microwave Theory Tech., Vol. 41, No. 6, 1233-1235, Jan. 1993.
18. McDonald, N. A., "Polynomial approximations for the electric polarizabilities of some small apertures," IEEE Trans. Microwave Theory Tech., Vol. 33, No. 11, 1146-1149, Nov. 1985.
19. McDonald, N. A., "Simple approximations for the longitudinal magnetic polarizabilities of some small apertures," IEEE Trans. Microwave Theory Tech., Vol. 36, No. 7, 1141-1144, Jul. 1988.
20. McDonald, N. A., "Polynomial approximations for the transverse magnetic polarizabilities of some small apertures," IEEE Trans. Microwave Theory Tech., Vol. 35, No. 1, 20-23, Jan. 1987.
21. McDonald, N. A., "Electric and magnetic coupling through small apertures in shield walls of any thickness," IEEE Trans. Microwave Theory Tech., Vol. 20, 689-685, Oct. 1972.
22. Pozar, M., Microwave Engineering, 2nd Ed., 333, Wiley, New York, 2003.
23. Kang, Y., S. Kim, M. Doleans, I. E. Campisi, M. Stirbet, P. Kneisel, G. Ciovati, G. Wu, and P. Yla-Oijala, "Electromagnetic simulations and properties of the fundamental power couplers for the SNS superconducting cavities," Proc. Particle Accelerator Conference, (PAC-2001), 1122-1124, Jun. 2001.