Lumped-Element and Leaky-Wave Antennas for Millimeter Waves

摘要

Some millimeter wave antennas can be scaled from their microwave frequency counterparts, but others cannot because of two main problems; the small wavelengths, which require small waveguide dimensions and pose fabrication difficulties, and higher metal loss. This contract was concerned with those antennas that cannot be scaled successfully, and it concentrated on novel leaky wave antennas. Two such waveguides were selected: the groove guide, and nonradiative dielectric (NRD) guide. Six different leaky wave antennas were analyzed on this program, with two treated in special detail. Three different leaky wave antennas were analyzed on this program, with two treated in special detail. Three different mechanisms for producing leakage were employed: asymmetry, foreshortening the structure's cross section, and using leaky higher modes. The different mechanisms also lead to different polarizations of the radiated fields. Accurate theoretical analyses were conducted for each of the antenna structures. Transverse equivalent networks were established, the elements of which were derived in closed form, so that the dispersion relations were also. Numerical values for the propagation characteristics were obtained as a function of various geometric parameters, to aid in the design of antennas based on these leaky structures. Special design considerations, including optimization procedures, were also developed when possible. In the case of the foreshortened top antenna based on NRD guide, detailed measurements were also taken, which showed very good agreement with our theory.