Patent ID: 6621459
Filing Date: 2003-09-16
Classification: H01Q

Abstract:
A plasma controlled reflector antenna, comprising:a reflector configured to reflect radio frequency (RF) radiation having a frequency equal to that of an operating frequency of the antenna; a feed for illuminating the reflector with and/or receiving from the reflector RF radiation at the operating frequency to transmit/receive RF radiation; a Fresnel zone plate (FZP) wafer adjacent the reflector and interposed between the reflector and the feed, the FZP wafer having a thickness substantially equal to n*&lgr;vac/(4*N), where n is an odd integer, &lgr;vac is the free space wavelength of RF radiation at the operating frequency, and N is the index of refraction of a material of which the wafer is made, in a non-plasma injected state; a controllable light source for projecting a controlled light pattern onto the FZP wafer to inject selectively plasma into regions of the FZP wafer illuminated by the light pattern, thereby creating regions in a plasma injected state and regions in a non-plasma injected state.