0.3-to-1.5-GHz LNA with Wideband Noise and Power Matching for Radio Astronomy

Abstract

This paper presents a low-noise amplifier (LNA) that was developed for a new radio telescope comprised of 512 parabolic dish antennas. The LNA closely interfaces to a custom-made antenna feed with an impedance co-designed to provide noise matching over a 5:1 bandwidth. Additionally, a method of broadband noise and power matching that allows the input impedance to be controlled independently from the optimum signal-source impedance to achieve minimum noise is also discussed. When measured in a 50-\Omega system, the LNA exhibits a return loss (RL) of > 8 dB between 0.32 to 1.5 GHz, S21 of 32 dB \pm 1.2 dB, IP1dB > -37 dBm, and IIP3 > -20 dBm. Noise parameter measurements show Tmin \approx 13 \pm 4K and noise temperatures T50{\Omega} \approx 18 \pm 6K between 0.5 to 1.4 GHz.