[Previous] | [Session 40] | [Next]
N. Zimmerman (Cooper Union), E. Kratzenberg, B. Corey (MIT Haystack Observatory)
The Low Frequency Array (LOFAR) will initiate a new era of astronomical discovery at the low frequency end of the electromagnetic spectrum by virtue of its large number of antennas (~13,000 each in multiple frequency bands), large spatial extent (~400 km), and wide frequency range (10-240 MHz). Each High Band Antenna, which covers 120-240 MHz, is an electronically steerable, compact array of ~16 dual-polarization receptors. The starting point for the antenna design -- a 4x4 square array of inverted-vee dipole receptors -- is studied using both electromagnetic computer simulations and prototype field testing. Through analysis at selected frequencies, the effect of spacing on the severity of grating lobes and beam steering is determined. In computer simulation, the shape of the dipole receptor is adjusted in order to optimize performance and ease of manufacture, and a particular model is highlighted which provides an improved beamwidth and greater sensitivity across the band of operation.
This work was funded by the REU program of the NSF.
[Previous] | [Session 40] | [Next]
Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.