The groove guide is a low-loss waveguide that was proposed by Tischer in 1963 as an alternative to classic waveguides. Its basic structure, can be divided into an inner and two outer region. The inner region exhibits a lower phase velocity. Hence, the electromagnetic field is concentrated in the inner region and propagates along the groove. In the outer regions, the electromagnetic field is eavnescent.

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The Groove-Guide Oscillator

When the periodic spacing of corrugated wavesguides is much less than wavelength λ, the slot width d≈L, and the space harmonics are neglected, the characteristic equation of corrugated square groove waveguides is formulated based on Maxwell's equations and boundary conditions.

The Characteristic Equation of Corrugated Square Groove Waveguides

When neglecting space harmonics and higher-order slot modes, the attenuation characteristic of corrugated circular groove waveguide has been investigated. It is shown that under certain conditions, the attenuation coefficient of HE11 mode will be lower than that of dominant TE(1)11 mode of circular groove waveguide with same radius.

Attenuation Characteristics of Corrugated Circular Groove Waveguide

An oversized-cavity millimetre-wave IMPATT oscillator has been constructed which can be easily coupled to a groove guide via a simple transformer. A resonant-cap structure is used to determine the frequency of oscillation. The oversized-cavity results in the Q of the oscillator being greater than that of a conventional impatt oscillator, but the output power and frequency are nevertheless stable. The tuning characteristic is discussed and a frequency spectrum presented.

S. Mak

Papers

IMPATT oscillator for groove guide at 95 GHz