Design, Fabrication and Test of a Metal-Grid Angular Filter

摘要

This final report describes the design, fabrication and test of a metalgrid spatial filter. The filter is a 5 x 5 foot flat panel incorporating 4 layers of crossed wire grids in a supporting structure of dielectric skins and dielectric honeycomb material. The spatial filter passes an electromagnetic wave incident within its angular passband centered on normal incidence, but reflects the wave if it is incident beyond about 30 degrees in the angular reject band. This result is obtained for any polarization of the wave. The filter operates at 9 GHz, and has a bandwidth of about 1 GHz for passing a wave at normal incidence. The measured characteristics of the spatial filter are close to those expected from analysis and previous tests of metal girds. There is more rejection for angles of incidence in the H plane than for incidence in the E plane. Placement of the spatial filter in front of a reflector antenna results in a significant reduction of antenna sidelobes beyond 30 degrees from the main beam in both the H plane and the E plane. There is only a slight degradation of the antenna sidelobes within the angular passband of the filter. (Author)