New Cooled Feeds for the Allen Telescope Array

Abstract

We have developed a new generation of low noise, broadband feeds for the Allen Telescope Array at the Hat Creek Observatory in Northern California. The new feeds operate over the frequency range 0.9 to 14 GHz. The noise temperatures of the feeds have been substantially improved by cooling the entire feed structure as well as the low noise amplifiers to 70 K. To achieve this improved performance, the new feeds are mounted in glass vacuum bottles with plastic lenses that maximize the microwave transmission through the bottles. Both the cooled feeds and their low noise amplifiers produce total system temperatures that are in the range 25-30 K from 1 GHz to 5 GHz and 40-50 K up to 12.5 GHz.

Precise measurements of self-absorbed rising reverse shock emission from gamma-ray burst 221009A

“…The newly refurbished, cryogenically cooled dual-polarization log-periodic feeds are sensitive to a broad range of radio frequencies, 1-10 GHz (ref. 59). Up to four independent frequency tunings, each ~700 MHz wide, can be selected anywhere in the radio-frequency band, theoretically allowing observers to tap into ~2.8 GHz of instantaneous bandwidth.…”

Strategy and Overview for Development of Beyond-Decade-Bandwidth Quad-ridge Flared Horns for Radio Astronomy

“…The strive towards ultra-wideband (UWB) receivers in the super high frequency (SHF) region of radio astronomy and space geodesy has produced a multitude of reflector feed options over the last two decades: Eleven feed [1], Dyson quad-spiral array (DYQSA), [2], Quad-ridge flared horn (QRFH) [3], log periodic Antonio feed [4], and Quasi selfcomplementary (QSC) feed [5]. This together with the development of new low-noise amplifier (LNA) technology (e.g.…”

Dielectrically Loaded Quad-Ridge Flared Horn for Beamwidth Control Over Decade Bandwidth—Optimization, Manufacture, and Measurement

“…UWB systems can reduce the number of receivers needed to cover a large frequency band. For large arrays with hundreds of reflector telescopes, such as the Square Kilometer Array (SKA) [1], the Allen Telescope Array (ATA) [2], and the Next Generation Very Large Array (ngVLA) [3], UWB systems could reduce manufacture and operations costs. The project Broadband (BRAND) [4] is to develop an UWB receiver from L-to Ku-band with one single feed [5].…”

“…Therefore, feed beamwidth control needs to be improved to push UWB receiver's sensitivity closer to that of narrowband systems. Different types of UWB feeds have been explored for radio astronomy: Eleven Feed [9], [10]; Antonio Feed [2]; quasiself-complementary feed (QSC) [11]; and quad-ridge flared horn (QRFH) [12], [13]. The QRFH is generally made entirely from low-loss metal and with a robust structure.…”