Antenna Properties of the Modified Luneburg Lens with Backward Radiation

A hemispherical Luneburg lens antenna with an air gap between the lens body and circular conducting screen is under consideration. Reflected rays create a directional radiation from the initial weakly directional irradiator. Suggested antenna structure decreases considerably the overall dimensions and weight of lens antennas. The influence of conducting screen size, the air gap and the lens radius on radiation antenna pattern is analyzed. It is noted that by adjusting the air gap the antenna back radiation level is changed. The scanning mode of the hemispherical Luneburg lens antenna with a conducting screen is investigated. The beamwidth, sidelobe level, directivity and scanning angle are calculated and compared. Radiation patterns of axial and scanning mode are shown.