New Leaky Wave Antenna for Millimeter Waves Based on the Groove Guide

摘要

Leaky wave antennas for millimeter waves face two main problems. The first relates to the small wavelengths involved, which require small waveguide dimensions and pose fabrication difficulties. The second problem is higher metal loss. In the new leaky wave antenna described and analyzed here, we overcome the first of these problems by choosing a structure with a longitudinally continuous aperture, and the second by basing the antenna on a low-loss waveguide, the groove guide. The groove guide is an open waveguide, but its dominant mode is purely bound by virtue of structural symmetry. By placing a longitudinal asymmetric metal strip along the guide, the symmetry is distributed and a new TEM-like mode is produced in the transverse direction that propagates to the open end and leaks power away. An accurate theoretical analysis is presented for the performance properties of this antenna structure. The cross section is represented by a transverse equivalent network that contains some subtle features. All of the elements of this transverse network are obtained in closed form, so that the dispersion relation for the propagation characteristics is likewise in closed form.