Admittance of a longitudinal slot radiating between baffles using a spectrum of two-dimensional solutions

The calculation of the equivalent admittance of a longitudinal slot radiating between baffles of finite height is discussed. A general method for analysis of waveguide slot antennas with arbitrary outer cross sections was introduced by Kildal et al. (1991). It was stated that, for large k/sub z/ values (wavenumber in z-direction), the slot cannot ´see´ the environment around it and the problem can be considered equivalent to that of a slot radiating in an infinite ground plane. It is noted that, by using this concept, it becomes much easier to perform the inverse transform. To find the slot admittance, the H-field between the baffles is found by using a spectrum of 2-D solutions. An integral equation is then formulated and solved for the slot E-field. The equivalent shunt admittance of the slot is then calculated. The normalized 2-D field solution at the transverse location of the slot is shown as a function of k/sub z/ for an isolated waveguide slot radiating into three different outer geometries: in an infinite ground plane, between baffles of infinite height, and between baffles of finite height.<>