Closely spaced high dielectric constant polyrod arrays

The paper describes the electrical properties of high dielectric constant materials for use as end fire rod radiators propagating in the hybrid TE11mode at microwave frequencies. Particular attention is devoted to the radiation characteristics of these units such as the velocity of propagation, sidelobe level, beamwidths and the impedance match to a feeding structure. The experimental data is compared favorably to polystyrene rods with a dielectric constant of 2.5. The materials studied were Alite, an aluminum oxide ceramic, R-1 Ferrite as manufactured by the General Ceramics Corporation, Ceramic NPOT96 and Tamco Ticon C, a calcium titanate ceramic with a dielectric constant of 165. The small diameters necessary for optimum radiation characteristics with high dielectric constant rods reduces the weight of the antenna to the extent that they are practical at UHF frequencies. The power handling characteristics of the high dielectric constant rods are limited only by the temperature dependence of the loss tangent, which is characteristic of the ceramic materials. A seventeen element array of Alite rods is described and its radiation patterns indicated for -band frequencies. Some data is also presented relating the conductance and susceptance of a ferrite rod to its depth of insertion in the narrow face of standard -band waveguide.