EE Devices Seminar - Sander Weinreb, Caltech/JPL
In the past the objects observed in radio astronomy were the 21cm hydrogen line, thermal emission from planets in our solar system, and from unusual stars and galaxies which typically did not change in a human lifetime. In the new era many objects of interest vary on a millisecond basis and the era is often called "time-domain astronomy". The objectives are pulses from neutron stars, time variation of planets around other stars, and emissions from the perimeter of black holes, and searches for emissions from other civilizations In many cases the direction in the sky of the unknown source is not known and the prime need is for survey speed rather than sensitivity to the radio flux from a direction pin-pointed by observations at other wavelengths.
These new objectives are best served by arrays of small radio telescopes and Caltech is designing a 2000 x 5m array to be located in Nevada and operating in the frequency rangadAe of 700 to 2000 MHz. The technology being developed for this array will be described including reflectors, feeds, low noise amplifiers (LNAs) , fiber-optic transmission over several km paths, and signal processing. Of special interest are the LNAs which are achieving 0.1dB noise figure without cryogenic cooling.