none

NRAO/Socorro Colloquium Series

Neal Erickson

University of Massachusetts

A 64 Element Phased Focal Plane Array for 70-95 GHz

Conventional heterodyne focal plane arrays (or FPA’s) have significant limitations in their performance with large gaps between elements and relatively poor coupling to the antenna over wide bandwidths due to the variation in the illumination.  FPA’s built utilizing phased array feed techniques can overcome these limitations and offer significant other performance enhancements. This approach uses a group of small antenna feeds to synthesize a single feed for the main antenna. Such an array of sufficient size can collect ALL of the energy in the focal plane, with Nyquist sampling. Phased combination of the elements of this focal plane array allows one to synthesize horns of optimal size and amplitude/phase distribution to enhance the telescope resolution and even compensate for telescope large scale errors.
    Phased array receivers have been built in the cm bands but near 90 GHz the required wavelength-scale packing of elements makes them far more difficult to build.  To demonstrate the technology, UMass and BYU are building an 8 × 8 array tuning the 70 – 95 GHz frequency range using a HEMT MMIC cryogenic front end, and a MMIC room temperature frequency converter.  It uses entirely digital beam combining over an IF bandwidth of 50-100 MHz.  Sensitivity of any single beam should be comparable to a conventional receiver using the same MMIC’s.  The goal of this work is to install this array on the 100m Green Bank Telescope within a three year schedule.  The long term goal is to show the feasibility of an array with ~1000 elements.



May 18, 2012
11:00 am

Array Operations Center Auditorium

All NRAO employees are invited to attend via video, available in Charlottesville Room 230, Green Bank Room 137 and Tucson N525.

Local Host:

Connect with NRAO

The National Radio Astronomy Observatory and Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.

The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."

AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.