A figure of merit, G/T, for a multichannel active array antenna was derived, and the effects of the beamforming network on the overall noise figure of the system were studied. Also examined are the dependence of the noise figure on various losses, and the difference between a resistive and nonresistive taper in the combining network. When the amplifier gain is sufficiently large, the losses following the LNA can usually be ignored. For a photonic array with lossy time shift elements, however, the downstream losses become significant. Also, if resistive tapering is employed, not only the array gain but also the noise figure will be degraded by the collective effect of the feed network. >

G/T and noise figure of active array antennas

[Editor's note: Three short articles concerning the definition of the gain of active antenna systems and planar arrays appeared on pages 62-64 of the October, 1989, Newsletter. The following comments were solicited by Antoine Roederer as a part of the questions he raised in the October issue, but unfortunately arrived a few da s too late to include in that issue. Alan J. Simmons ($0 Box 103, Winchester, MA 01890) and Donald G. Bodnar (GTRI/CCRF/STL/ATD-Room 4-138, Georgia Institute of Technology, Atlanta, GA 30332 also solicited input from M - S regarding the gain o d active antenna s stems, as a result of discussions at an Antenna StandYards Committee meeting during the San Jose symposium. This later input was sollcited on behalf of the Committee. Those wishing to contribute to this discussion are requested to send their comments to the appropriate author, with copies to Alan Simmons or Donald Bodnar, who will act as coordinators for these discussions. WRS]

http://ieeexplore.ieee.org/iel5/8233/6102030/06102043.pdf

John Hang

Papers

Further comments on the definition of antenna gain