A Wideband Single Polarization Radio Receiver - Precursor to Low Frequency Radio Telescope

The low frequency radio telescope (LFRT) is a new initiative undertaken by the Raman Research Institute (RRI) for exploring the radio sky at low frequencies. Transient sky till date, has remained almost unexplored and is expected to open up a new dimension of astronomical exploration. For detecting transients routinely over a large volume of space at frequencies below 300 MHz, there does not seem to exist anywhere in the world an optimized setup with required sensitivity. In this context, a wide band single polarization radio receiver as a precursor to the LFRT has been built by RRI to operate in the frequency range of 30 – 360 MHz. This has been realized using two 1:3 bandwidth antennas covering the frequency ranges 30 – 90 MHz and 120 – 360 MHz respectively. It is expected to have i) instantaneous bandwidth of about 300 MHz and ii) a wide field coverage of 2π Steradian. We describe in this paper, the design of a wide band radio receiver system consisting of i) frequency independent broadband antennas ii) compact analog delay line for producing multiple beams in the sky iii) a high dynamic range front end receiver and iv) a 1024 channel precision spectrometer, along with its performance characteristics. The initial results obtained confirm i) the frequency independent behaviour of the antenna over its design bandwidth and the ii) the delay expected out of the compact analog line implemented on the water-based substrate.