The usual aim with any waveguide is to operate it with only the fundamental mode propagating. With fully closed waveguides, finding the band over which this is possible turns on no more than knowledge of the cutoff frequencies of the fundamental and first higher order modes. With open waveguides, the question is not so simply answered. Such waveguides propagate at most a finite set of bound modes together with a continuous modal spectrum that has no counterpart with closed guides. In this paper, for several particular two-conductor transmission lines, we investigate the circumstances under which leaky wave modes, though not themselves members of any orthonormal set of basis functions, can be used to set bounds on the band over which it is to be expected that the transmitted field is substantially contained in the fundamental TEM mode. The method used relies on transverse resonance.
2. Sorrentino, R., "Transverse resonance technique," Numerical Techniques for Microwave and Millimetre-wave Passive Structures, 1989.
3. Rozzi, T. and M. Mongiardo, Open Electromagnetic Waveguides, Institution of Electrical Engineers, London, First Edition, 1997.
4. Friedrichs, K. O., "Criteria for discrete spectra," The Theory of Electromagnetic Waves, 1951.
5. Tamir, T., "Leaky wave antennas," Antenna Theory Pt 2, 1969.
6. Langston, W. L., J. T. Williams, D. R. Jackson, and F. Mesa, "Spurious radiation from a practical source on a covered microstrip line," IEEE Trans. Mic. Th. Tech., Vol. MTT-49, 2216-2226, 2001.
7. Shigesawa, H., M. Tsuji, and A. A. Oliner, "The nature of the spectral-gap between bound and leaky solution when dielectric loss is present in printed-circuit lines," Radio Sci., Vol. 28, 1235-1243, 1993.
8. Rotman, W., The channel guide antenna, Proc. Natl. Electron. Conf., Vol. 5, 190-202, 1949.
9. Marcuvitz, N. (ed.), Waveguide Handbook, First Edition, Dover Publications, 1965.
10. Cullen, A. L., "On the channel section waveguide radiator," Phil. Mag., Vol. 40, 417-428, 1949.
11. Collin, R. E., Foundations for Microwave Engineering, First Edition, McGraw-Hill Book Coy., 1966.
12. Marin, L., "Transient electromagnetic properties of two, infinite parallel wires," J. App. Phys., Vol. 5, 335-345, 1975.
13. Melino, R. and H. E. Green, "An error in the 'Waveguide Handbook'," IEEE Trans. Mic. Th. Tech., Vol. MTT-48, 2000.
14. Love, A. E. H., Some electrostatic distributions in two dimensions, Proc. London Math. Soc., Vol. 22, 1923.
15. Morse, P. M. and H. Feshbach, Methods of Theoretical Physics, First Edition, McGraw-Hill Book Coy., 1953.
16. Moon, P. and D. Spencer, Field Theory Handbook, First Edition, Springer-Verlag, 1961.
17. Green, H. E., "A simplified derivation of the capacitance of a twowire transmission line," IEEE Trans. Mic. Th. Tech., Vol. MTT- 47, 365-366, 1999.
18. Harrington, R. F., Time Harmonic Electromagnetic Waves, First Edition, McGraw-Hill Book Coy., 1961.
19. Altman, J. L., Microwave Circuits, First Edition, Van Nostrand Coy., 1964.