Normal Modes in Overmoded Dielectric-Lined Circular Waveguide

Abstract

The propagation constants (loss and phase) are determined for the normal modes in dielectric‐lined overmoded (guide radius ≫ wavelength) circular guide by numerical solutions of the appropriate characteristic equations. It is shown that the heat loss of the TMpn modes is quite low and decreases with increasing frequency in contrast to the increase in heat loss predicted by the perturbation theory for thin linings. The primary effect of the low‐loss TMpn modes on a transmission system using the TE01 mode is a reduction in the route bend losses.

Modes in silver-iodide-lined hollow metallic waveguides mapped by terahertz near-field time-domain microscopy

“…Corrugations and dielectric inclusions were also designed to transform the TE 11 eigenmode of the cylindrical waveguide to the optical-fiber-like hybrid HE 11 mode. This hybrid mode is well confined in the hollow core of the waveguide, with the propagation loss and attenuation due to bends smaller than for the TE 01 [2,3,10,11]. Moreover, unlike the TE 01 mode, the linearly polarized HE 11 mode facilitates the conversion to a free-space linearly polarized Gaussian beam.…”

“…Experimental and theoretical development in this area started in the millimeter-wave regime [2][3][4]. In light of the high losses suffered by the TE 10 of the traditional rectangular waveguides and the transverse electromagnetic mode of coaxial waveguides, microwave engineers shifted their interest to cylindrical waveguides and their TE 0n modes (where n is an integer and denotes radial variation) because of their low attenuation at high frequencies [5].…”

“…In light of the high losses suffered by the TE 10 of the traditional rectangular waveguides and the transverse electromagnetic mode of coaxial waveguides, microwave engineers shifted their interest to cylindrical waveguides and their TE 0n modes (where n is an integer and denotes radial variation) because of their low attenuation at high frequencies [5]. However, the TE 01 mode is degenerate with the highly lossy TM 11 mode, and researchers then examined strategies to break this degeneracy by, for instance, corrugations [6,7] or dielectric coatings [2][3][4]8,9]. Corrugations and dielectric inclusions were also designed to transform the TE 11 eigenmode of the cylindrical waveguide to the optical-fiber-like hybrid HE 11 mode.…”

“…Corrugated waveguides have been the mainstream in high-energy science where strong interaction with an axial electron flux is pursued [12,13] and an active line in antenna research [6,14]. Dielectric-lined cylindrical waveguides were meanwhile developed for communication systems [2][3][4]; however, they were abandoned later in favor of optical fibers. These waveguides were recuperated subsequently for high-power delivery as well as for surgical applications with midinfrared lasers [15,16].…”

Silver-Coated Teflon Tubes for Waveguiding at 1–2 THz

“…By introducing a dielectric coating on the inner metallic walls of an oversized waveguide (as a rule of thumb,~λ 0 /4 thick), the waveguide dominant mode becomes the linearly polarized hybrid HE 11 mode [1][2][3][4][5][11][12][13][14][15][16]. This HE 11 mode is advantageous because it suffers low losses and it couples efficiently to freespace linearly polarized Gaussian beams [11,17].…”