CRAL
Cahill Radio Astronomy Lab

COMAP - the CO Mapping Array Pathfinder



The CO Mapping Array Pathfinder (COMAP) will open a new window on both the Epoch of Reionization (EoR) and the Epoch of Galaxy Assembly by using carbon monoxide (CO) lines to trace the distribution of star-forming galaxies in both epochs. Phase I of COMAP comprises a 10-m telescope, located at the Owens Valley Radio Observatory (OVRO), equipped with a 19-pixel, dual polarization spectrometer array that will map a total of 10 square degrees of sky in the frequency range 30-34 GHz, with spectral resolution R~800. This band will be sensitive to CO(1-0) in the redshift slice z=2.4-2.8 and to CO(2-1) in the redshift slice z = 5.8-6.7.

The project is a collaboration between Caltech (Kieran Cleary PI), Stanford University, JPL, University of Maryland and the University of Miami.

  • Observed frequency of CO lines versus redshift. The COMAP band at 30-34 GHz is sensitive to the 1-0 line from z~2.6 and the 2-0 line from z~6.4.

  • A 3mm spectroscopic array for GBT

    Argus, a 16-pixel spectrometer, which will enable fast astronomical imaging over the 85–116 GHz band. Each pixel includes a compact heterodyne receiver module, developed at the CRAL, which integrates two InP MMIC low-noise amplifiers, a coupled-line bandpass filter and a sub-harmonic Schottky diode mixer (see figure to right). The receiver signals are routed to and from the multi-chip MMIC modules with multilayer high frequency printed circuit boards, which includes LO splitters and IF amplifiers. Microstrip lines on flexible circuitry are used to transport signals between temperature stages. The spectrometer frontend is designed to be scalable, so that the array design can be reconfigured for future instruments with hundreds of pixels. Argus is scheduled to be commissioned at the Robert C. Byrd Green Bank Telescope in 2015.

    The project is a collaboration between Caltech, Stanford University (Sarah Church PI), JPL, University of Maryland and University of Miami

  • Interior of the Argus front end module showing MMIC amplifiers and the IQ mixer.

  • Next-generation MMIC amplifiers

    The CRAL collaborates with JPL and Northrop Grumman (NGC) to improve the performance of InP HEMT amplifiers for radio astronomy. This program leverages the commercial investment in short gate-length transistor processes at NGC to optimise MMIC amplifier designs for radio astronomy in the key atmospheric windows. The collaboration has resulted in record-setting noise temperature performance at frequencies from 70-300 GHz (see figure to right) using the 35 nm process. Further improvements are expected as designs are optimised and shorter gate-length processes become available at NGC.

  • Record-breaking MMIC amplifier noise temperatures from the Caltech, JPL, NGC collaboration.



  • A key component of this process has been the development at the CRAL of a cryogenic probe station (see figure to left), which allows the MMIC chips to be non-destructively characterized at cryogenic temperatures. This has been achieved at frequencies up to 116 GHz although higher-frequency measurements are possible. This new test facility enables the efficient screening of large numbers of MMIC amplifiers - a key requirement for the fabrication of large format focal-plane arrays.