Primitive Impulse Response Function for Near-Field Calculation and Its Accuracy

In this letter, we present a method of calculating the monochromatic field radiated from a uniformly illuminated aperture. We show that closed-form functions are available in the time domain, which lead to frequency domain results. The time dependence of the field is calculated as the derivative of the primitive impulse response function (PIRF) of the aperture. PIRF itself is represented by an incomplete elliptic integral of the second kind. Analytic method shown in this letter is much more efficient in computer resources than the numerical technique, finite integration technique, to which we compare.