Aperture distribution analysis of a flat plate antenna from short range pattern measurements

Flat plate antennas have recently been developed which have square apertures with sides from 190 to 470 mm, operating between 11 and 12 GHz. Three examples are shown, an 8×8 circularly polarised (c.p.) array, a 16×16 c.p. array and a 20×20 dual linearly polarised array. The applications for these are DBS radio, DMAC DBS television, and Astra DBS television. These flat plate antennas have their distribution network and the antenna probes as an integrated structure, so that it is impractical to measure the distribution network in isolation. Accordingly a technique has been developed which deduces the performance of the distribution network form the observed radiation patterns. At the same time, the practical limitations set by anechoic chamber size can be calibrated out of the process. In the present case, measurements at a range of d²/λ were involved (a 7 metre chamber)