Numerical analysis of a grid array antenna

A grid array antenna printed on a dielectric substrate is analyzed using the method of moments. The impedance matrix element is separated into a singularity term and a perturbation term. To save computing time, an interpolation technique is applied to the perturbation term. Numerical results show that a traveling wave with some decay is dominant in the current distribution on the grid wire. Calculations based on the obtained current distribution reveal that the radiation beam direction moves toward the antenna plane, as the frequency decreases. The gain is found to be lower than that for a grid array antenna on an air substrate