Impact of bandwidth on antenna‐array noise matching

Abstract

This letter expands the treatments of wideband noise analysis of antenna arrays by including bandwidth effects on beam‐equivalent receiver noise temperature, $T_{\text{rec}}$, and the active reflection coefficient, ${\mathrm{\Gamma }}_{\text{act}}$. The particular focus of the letter is on receiver noise decorrelation in wideband systems having noise bandwidth $f_{\mathrm{B}}\gg$1 Hz. The new analysis and simulations show increase in $T_{\text{rec}}$ and the departure of ${\mathrm{\Gamma }}_{\text{act}}$ from that obtained using contemporary analyses for $f_{\mathrm{B}}=$1 Hz. Although the paper also shows that for many applications over moderate bandwidths and close connection between the receiver and array the influence of $f_{\mathrm{B}}$ on $T_{\text{rec}}$ is not significant, the simulations of a 71‐element array demonstrate that the noise decorrelation due to wide $f_{\mathrm{B}}$ can result in tens of percent (as much as 45.5% in simulations described in this letter) increase in $T_{\text{rec}}$ above the low‐noise amplifier minimum noise temperature, which should be taken into account at the design stage of ultra‐wide band systems, such as those under investigation by, for example, the Defense Advanced Research Project Agency (DARPA) in its wideband adaptive RF protection (WARP) program and ultra‐sensitive active electronically scanned array (AESA) radars for tracking stealth objects.