| 摘要 |
<p>A non-mechanical beam deflector (Figs. 21A-23B) forms and scans a beam of millimeter wave (MMW) radiation, from a MMW source (268), at a rapid rate. The beam deflector includes a semiconductor body (160, 280) in which a spatially varying density of charge carriers is selectively injected, e.g., through selective optical exposure by means of an LED array (262). The injected charge carriers - electrons and/or holes - alter the dielectric constant of the semiconductor body (160, 180) locally and thereby attenuate and reflect incident MMW radiation. The portions of the semiconductor body that do not have carriers injected therein allow the incident MMW radiation to be transmitted. The semiconductor body, modified with a spatially varying density of charge carriers, diffracts the radiation which passes through it into a beam. The beam may be scanned across space through selective control of the injected charge carriers, achieved, e.g., by appropriate control of the LED array (262) by an LED control circuit (265). The diffractive conditions can be rapidly reconfigured. The spatially varying density of charge carriers may be induced optically into the semiconductor body, or directly injected using opposing p- and n-type contacts forming a p-n junction. A dynamically variable Fresnel zone plate (FZP) represents one application of the invention.</p> |
