A wire grid angular filter for antenna pattern measurement

A novel wire grid angular filter has been described with the property that, for a particular grid separation and frequency, plane-waves incident over a narrow spread of angles will be strongly reflected, while those incident at other angles will be transmitted. An experimental device has been constructed and preliminary measurements at normal incidence have shown that the resonance effect does occur. The performance of the device is limited by the uneven height of the wires of each grid and that it appears to operate only at normal incidence. This configuration of a pair of wire grids can form the basis of an angular filter. Only waves incident normally will be strongly reflected, while waves incident at other angles will be transmitted. Such a filter might also be used to produce a plane wavefront for the measurement of antenna radiation patterns, since the reflected wave will have a very narrow angular spread