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We present an analysis on wave propagation in superconducting circular waveguides. In order to account for the presence of quasiparticles in the intragap states of a superconductor, we employ the characteristic equation derived from the extended Mattis-Bardeen theory to compute the values of the complex conductivity. To calculate the attenuation in a circular waveguide, the tangential fields at the boundary of the wall are first matched with the electrical properties (which includes the complex conductivity) of the wall material. The matching of fields with the electrical properties results in a set of transcendental equations which is able to accurately describe the propagation constant of the fields. Our results show that although the attenuation in the superconducting waveguide above cutoff (but below the gap frequency) is finite, it is considerably lower than that in a normal waveguide. Above the gap frequency, however, the attenuation in the superconducting waveguide increases sharply. The attenuation eventually surpasses that in a normal waveguide. As frequency increases above the gap frequency, Cooper pairs break into quasiparticles. Hence, we attribute the sharp rise in attenuation to the increase in random collision of the quasiparticles with the lattice structure.
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K. C. Walker, J. W. Kooi, M. Chan, H. G. Leduc, P. L. Schaffer, J. E. Carlstrom, T. G. Phillips, A low-noise 492 GHz SIS waveguide receiver, Int. J. of Infrared and Millimeter Waves 13: 785 – 798, 1992.
K. H. Yeap, K. C. Yeong, C. Y. Tham, H. Nisar, Analysis of Energy Loss in Superconducting Waveguides, Biologically-Inspired Energy Harvesting through Wireless Sensor Technologies, IGI Global, Pennsylvania, 2016.
J. H. Winters, C. Rose, High-Tc superconductors waveguides: Theory and applications, IEEE Transactions on Microwave Theory and Techniques 39: 617 – 623, 1991.
G. Yassin, C. Y. Tham, S. Withington, Propagation in lossy and superconducting cylindrical waveguides, Proc. of the 14th Int. Symp. on THz Technology, Tucson, Arizona, pp. 516 – 519, 2003.
K. H. Yeap, C. Y. Tham, K. C. Yeong, H. J. Woo, Wave propagation in lossy and superconducting circular wavguides, Radioengineering J. 19: 320 – 325, 2010.
M. J. Wengler, Submillimeter-wave detection with superconducting tunnel diodes, Proc. of IEEE 80: 1810 – 1826, 1992.
B. Mitrovic, L. A. Rozema, On the correct formula for the lifetime broadened superconducting density of states, J. Phys. Condens. Matter 20: 015215, 2008.
T. Noguchi, T. Suzuki, A. Endo, T. Tamura, Contribution of the imaginary part of the superconducting gap energy on the SIS tunneling current, Physica C 469: 1585 – 1588, 2009.
T. Noguchi, T. Suzuki, T. Tamura, Subgap tunneling current at low temperature in Nb/Al-AlN/Nb SIS junctions, IEEE Transactions on Appl. Superconductivity 21: 756 – 759, 2011.
T. Noguchi, M. Naruse, Y. Sekimoto, RF conductivity and surface impedance of a superconductor taking into account the complex superconducting gap energy, Phys. Proceedia 36: 318 – 323, 2012.
T. Noguchi, M. Naruse, Y. Sekimoto, Contribution of quasiparticles in the subgap states to the surface impedance of superconductors, IEEE Transactions on Appl. Superconductivity 23: 1501404, 2013.
K. H. Yeap, J. S. M. Teh, H. Nisar, K. C. Yeong, K. Hirasawa, Attenuation in superconducting rectangular waveguides, Frequenz J. of RF-Engineering and Telecommunications 69: 111 – 117, 2015.
P. L. Kautz, Picosecond pulses on superconducting striplines, J. of Appl. Phys. 49: 308 – 314, 1978.
K. H. Yeap, C. Y. Tham, K. C. Yeong, K. H. Yeap, A simple method for calculating attenuation in waveguides, Frequenz J. of RF-Engineering and Telecommunications 63: 236 – 240, 2009.
K. H. Yeap, C. Y. Tham, K. C. Yeong, E. H. Lim, Full wave analysis of normal and superconducting microstrip transmission lines, Frequenz J. of RF-Engineering and Telecommunications 64: 56 – 66, 2010.
K. H. Yeap, C. Y. Tham, G. Yassin, K. C. Yeong, Attenuation in rectangular waveguides with finite conductivity walls, Radioengineering J. 20: 472 – 478, 2011.