Amplitude Modulation with Phased-Array Antennas.

摘要

A technique for generating amplitude-modulated signals at a distant point in space is described. This technique does not utilize any amplitude modulators or amplitude-modulated devices; however, a phased-array antenna is used with appropriate element phase modulations to produce the desired amplitude changes. The advantage of this technique is that it uses simple efficient continuous-amplitude devices for power generation and avoids the well-known problems associated with producing and amplifying AM signals. This technique will be more attractive as phased-array antennas and their increased capabilities are more fully utilized. Two classes of modulated phased-array antennas are identified, a beam-steering class and a generalized modulation transfer-function class. The theory of both classes is presented, and many experiments are described for the simpler beam-steering class. Step-recovery-diode sources are used for microwave signals and for phase shifting. Their properties and several problems are presented. (Author)