A Compact Filter-Bank Waveguide Spectrometer for Millimeter Wavelengths

TL;DR

This paper introduces a compact, waveguide-based millimeter-wave spectrometer prototype for astronomical use, demonstrating design, fabrication, and measurement results that align with simulations, and proposing a scalable 54-channel version for atmospheric window observations.

Contribution

The paper presents a novel compact waveguide spectrometer design, validated through measurements, and extends it to a high-channel-count version suitable for millimeter-wave astronomical spectroscopy.

Findings

Prototype measurements match electromagnetic simulations.

The 54-channel design covers key atmospheric windows.

The device can be tiled into 2D arrays for telescope focal planes.

Abstract

We present the design and measurements of a 90GHz prototype of a millimeter-wave channelizing spectrometer realized in rectangular waveguide for astronomical instrumentation. The device was fabricated using conventional high-precision metal machining, and the spectrometer can be tiled into a 2D array to fill the focal plane of a telescope. Measurements of the fabricated five-channel device matched well with electromagnetic simulations using HFSS and a cascaded S-matrix approach. This motivated the design of a 54-channel R=200 spectrometer that fills the single-moded passband of rectangular waveguide in the 130-175 GHz and 190-250 GHz atmospheric windows for millimeter-wave spectroscopic mapping and multi-object spectroscopy.