Wideband Feed and Reflector Ground Shield for the Deep Synoptic Array (DSA-2000)

Abstract

We present the low-cost, dual-polarized, wideband quad-ridge choke horn (QRCH) feed with a low-loss dielectric lid optimized for the Deep Synoptic Array (DSA-2000) in radio astronomy. The ridges and dielectric lid allows for a compact feed diameter with small blockage of the 5-meter-diameter axially-symmetric prime-focus reflector. A wide feed pattern suitable for applications with f/D below 0.35 is achieved over the frequency range 0.7-2 GHz. The band-average aperture efficiency in simulation is 66 % in the unshaped reflector including blockage. An extension of the reflector rim reduces the spillover noise contribution to less than 1 K at zenith pointing. Together with an excellent ambient temperature low-noise amplifier developed for DSA-2000 the predicted system noise temperature is 25 K.

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