Antenna system with plural reflectors

摘要

An antenna system (10) having a front reflector (12) and a rear reflector (14) arranged in tandem, a front feed (16) for illuminating the front reflector (12), and a rear feed (18) for illuminating the rear reflector (14). Each of the reflectors has a generally dish-shaped configuration, and the feeds are located in positions offset from axes of the respective reflectors. The front reflector (12) is reflective to a first radiation, while being substantially transparent to a second radiation except for a fraction of the power of the second radiation. The fractional part of the second radiation is reflected from the first reflector (12) as an interfering beam, the interfering beam being scanned away from a coverage region of a beam (28) of the first radiation by an offset between the feeds (16, 18). The radiations may differ in polarization or in frequency. There may be a complete shading of the rear reflector (14) by the front reflector (12) from the radiation of the rear feed (18) to produce uniform illumination of the rear reflector for greater accuracy in a formation of a beam from the rear reflector. Six degrees of freedom in positioning and orientation of the reflectors (12, 14) and their feeds (16, 18) provides maximum design flexibility for obtaining a compact antenna.