Antenna radiation pattern measurement using a near-field wire scattering technique

A method of measurement of antenna radiation patterns is described. The variations in reflection coefficient at the antenna feed were recorded as a thin wire is moved past the antenna aperture. It is shown that for antennas whose aperture distributions are separable, the change in reflection coefficient is approximately proportional to the square of the integrated aperture field at the position of the wire. By taking the square root of the change in reflection coefficient due to the signal scattered from the wire, as a function of wire position, the integrated aperture field can be obtained, and hence one cut of the far-field radiation pattern. An experimental system has been constructed, and comparisons are presented of radiation patterns measured using the scanning wire technique with those of the same antennas measured on a far-field range, demonstrating good agreement. The technique should provide a rapid and simple method of checking antenna performance.