Description
The Expanded GMRT (eGMRT) is a proposal to look at three expansions to the
GMRT - increasing the field of view, increasing angular resolution and
improving the sensitivity to the extended radio emission. In this talk, we
would focus on the testing of multi-element, multi-beam beamformer using
the
144-element Focal Plane Array (FPA) procured from ASTRON.
The preliminary tests for the beamformer are being carried out with FPA as
an
aperture array. A free-space test range, meeting the far-field
requirements at
L-band, has been developed at the GMRT site. The narrow beamwidth
transmitting
antenna (a 3m diameter parabolic dish and a cross-dipole feed at the
prime-focus) required for beampattern measurement and beamsteering
experiments was fabricated at NCRA. Beamsteering measurements have been
carried out by radiating continuous wave and broadband noise in this test
range. Tests have also been carried out to observe navigational satellites
in the L-band with the transmitting antenna used for "phasing" the array.
The test methodology, details of the experiments and the results would be
described. The test results from the beamsteering experiments show a close
match with the theoretically expected outcome. The entire process of
testing from setup to data acquisition and analysis is automated to allow
for a speedy understanding of the data and efficient debugging.
Currently, we are working to test multiple beams in the field-of-view (FoV)
by applying optimal beamforming weights.
