Improvement technique in the C/I of a high-power-amplifier array using intermodulation distortion controllers

The transponders for future communications satellite, must have high output power with high efficiency and low intermodulation distortion. This paper examine the third-order intermodulation distortion (IM3) reduction performance of a single high-power-amplifier (HPA) with even-order-distortion implemented intermodulation distortion controller (EODIC). Furthermore, a new technique is proposed to improve the carrier to interference ratio (C/I) in an active-phased-array antenna that uses EODICs. The technique combine the intermodulation distortions of each array element in such a way that they cancel or are distributed away from the mainlobe direction. The applicability of this technique is evaluated using the measured performance of the EODIC in an HPA to an active-phased-array antenna, in a simulations of the radiation patterns of the carrier and the IM3. The calculated results show that the C/IM3 in the mainlobe direction is greatly improved by this technique.