Nonlinear distortion reduction in active arrays taking advantage of their spatial power-combining properties

In this article, a linearity-improving technique for active antennas and arrays, based on spatial power combining, is presented. An auxiliary branch is employed to cancel the radiation pattern at the intermodulation distortion (IMD) components, either in the mainbeam direction for a subarray or in all elevation angles for a single antenna element. The need for precise amplitude and phase control over the IMD currents in the array auxiliary elements is demonstrated, quantifying the possible degradation suffered in the carrier-to-intermodulation distortion (CIMD) ratio improvement obtained when this solution is applied. The potentialities of implementing the derivative-superposition technique in small- and large-signal regimes, both in an array and in an antenna element, are finally proposed. (C) 2005 Wiley Periodicals, Inc.