Sense and sensitivity: How ALMA receivers work

TL;DR

This paper explains the design and function of ALMA receivers, detailing how they convert and amplify high-frequency electromagnetic signals collected by the antennas for astronomical imaging.

Contribution

It provides a detailed explanation of the unique design and operation of ALMA receivers, highlighting their specialized role in radio astronomy.

Findings

ALMA receivers convert high-frequency signals to lower frequencies for processing.

They amplify signals to enable detailed astronomical imaging.

The design is specialized compared to normal AM receivers.

Abstract

In previous articles, we described how electromagnetic waves emitted from objects in the sky are collected by the ALMA antennas (Anatomy of ALMA), and how they are combined in order to produce images. Before these images can be processed, they are picked up by the antennas and concentrated by the large main mirror and a smaller secondary mirror in the so called focal point of each antenna. In order to process the data they must be first converted to electromagnetic waves of a lower frequency and amplified. This is the role of the ALMA receivers. In principle they work like a normal AM receiver, but at much higher frequencies. Here we describe how they work and what makes them special.