Propagation in nonuniform waveguides with impedance walls

Abstract

Under cer tain co ndi tions i t is useful to exchange Maxwell's equations for a n . infinite set of cou pled total differential equations; the set takes t he form of ge neralized teleg raphist's equ ations. This is done for a p a rallel-plate wavegu id e with impeda nce walls and var ying plate separation. The cha racteristic modes of t he waveguide a re used in order t hat couplin g betwee n equ atio ns depends only on geometric p er turbations o f t he guide walls. The u t ili ty of the techn ique is de monstrated by evalu ating t he mode co n ve rs ion in an overmoded wavegu ide co ntaining a geometric p ert urbation. A co mpa riso n wi t h experim ental work is prese nted fo r t he perfectly co nd ll etin g case.

Scattering parameters representing imperfections in precision coaxial air lines

“…Skin effect coupling on the conductor surfaces was also reported by Schelkunoff and Gallawa [10]. When the air line is operated at frequencies appropriate to the principal mode, all TM modes attenuate rapidly below their cutoff frequencies.…”

“…Following Schelkunoff [7], Reiter [8], Solymar [9] and Gallawa [10], generalized telegraphist equations for the principal mode are derived in section 2 for a circular air line. Transformation to forward and backward wave differential equations enables general solutions for the scattering parameters in section 3.…”

Depolarization and Scattering of Electromagnetic Waves. Appendices.

“…in which Z is an impedance diadic (Gallawa 1964), (as in the case of highly reflecting boundaries such as good conductors), the electromagnetic fields may be expanded completely in terms of waveguide modes. The wave spectrum in this case is discrete (the radiation fields and lateral wave contributions 190 vanish).…”

Theory of irregular impedance waveguides: Generalized method of separation of variables

“…Although the basis may be formed by eigenfunctions and associated functions [9], the mathematical properties of such spectral problems may be very complicated and, up to now, such an approach has not been used consequently for practical applications. Only a partial case of a planar irregular impedance waveguide had been considered in [10]. But the issue regarding the completeness of the used basis functions had not been discussed.…”