Comprehensive Measurement of Aperture Fields, Near-Fields and Far-Fields of a Large Reflector Antenna from a Microwave Hologram

A microwave holographic technique is used to obtain quantitative data on the amplitude and phase of the principal and cross-polarised fields in the aperture of a large reflector antenna. The hologram formation process utilises the existing scanning system of the antenna. Data is processed computationally using the FFT and is visually displayed in hard copy with 32 levels. The lateral and longitudinal positioning of the E- and H-plane phase centres of the feed is located and the r.m.s. value of the reflector surface profile errors obtained. Accurate prediction of E- and H-plane radiation patterns in any section of the near and far fields can be obtained from the reconstructed aperture distributions. The technique provides a total description of the antenna.