Performance of the wire-grid lens HF antenna

The wire-grid lens HF antenna is a high-frequency realization of a two-dimensional Luneburg lens. This vertically polarized high-directivity 36-beam circular antenna can operate over a 10/1 frequency band. When receiving a signal on a single beam, it exhibits a low binary-error rate equivalent to that of a nest of three high-gain rhombics required to cover the same frequency band. Improved reception is obtained by receiving a signal on a pair of adjacent beams operating in the angle-diversity mode. As a direction-finding antenna, its accuracy is limited primarily by irregularities in ionospheric propagation. Its theoretical performance, which has been calculated with precision on a high-speed digital computer, is compared with its measured performance.