Importance

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Abstract

An equal power amplifier system (100) for amplifying a plurality of signals for transmission by an active phase array antenna (20), and a compact plural level beam-forming network (98) for forming a plurality of such signals, for example on excitation patterns for frequency scanned virtual beams, are disclosed. The amplifier system uses at most only a few sizes of power amplifiers (130, 134) to amplify efficiently numerous signals having significantly different amplitudes. This is accomplished by distributing the task of amplifying signal pairs (A.sub.i, B.sub.i) composed of one large amplitude signal and one small amplitude signal to an equal power amplifying apparatus (130; 230), which includes two hybrid couplers (236, 238) and two equally sized power amplifiers (232, 234). The first hybrid coupler (236) divides the two signals (A.sub.i, B.sub.i) for input into the two power amplifiers. The second hybrid coupler (238) receives the intermediate amplified signals from the power amplifiers and through constructive and destructive interference produces amplified output signals (A.sub.i *, B.sub.i *) corresponding to the input signals. Also disclosed is a method for properly selecting pairs of signals from an amplitude distribution (200; 202) for application of such equal power amplifying apparatuses of the amplifier system in order to operate the power amplifiers therein at or near peak efficiency. The beam-forming network (98) is arranged on two levels to simplify interconnection of the selected pairs of outputs of its line summers (176) for input into the equal power amplifier system. The amplifier system and beam-forming network may be used together, for example, in the transmit antenna system of a geosynchronous satellite (10) or mobile earth station.

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First Claim