RADIATION PATTERN ANALYSIS OF THE TAPERED SLOT ANTENNA (ELECTROMAGNETICS, MICROWAVES)

A theoretical model for the radiation characteristics of the tapered slot antenna is presented. The theory presented is valid for antennas having an arbitrary and smooth taper shape. The model adequately predicts the pattern dependence on the structural parameters of the antenna such as its length, the taper shape, the dielectric substrate and its thickness. The antenna is modelled as a tapered slot radiating in the presence of a conducting half-plane. The electric field distribution in the tapered slot is determined by effecting a stepped approximation to the continuous taper. Data on a uniform slot line is used to determine the slot field distribution in the stepped model. The uniform slot line is solved by the spectral Galerkin's method and data on the slot wavelength and the characteristic impedance are generated. Closed form expressions for these slot line parameters are developed. The half-plane Green's function is used to compute the radiated fields from the tapered slot. Comparison is made between the computed and measured radiation patterns. Results are presented for the cases of a constant width, a linear taper and an exponential taper of the slot and the versatility of the model in treating an arbitrary slot taper is demonstrated. Newly observed experimental effects concerning the pattern dependence on the lateral dimension of the antenna are presented. Studies done to account for these effects for the special case of an air dielectric antenna are presented.