Design Of An Ultra-Long Wavelength Experimental Radio Array

The Ultra-Long Wavelengths (ULW) regime of longer than 10 m (frequencies below 30 MHz), remaining as the last virtually unexplored window in radio astronomy, is presently attracting more and more attentions due to some key sciences. However, the opaqueness of the Earth's ionosphere makes ULW observations below 10 MHz by terrestrial facilities practically impossible. Furthermore, the ULW spectrum is full of artificial radio frequency interference (RFI). The feasible solution for both problems is to build an ULW space-borne telescope, it is, however, very costly and challenging in both technology and engineering. Recently, studies reveal that the period post 2020 will be an appropriate opportunity to conduct systematic ground based ULW radio observations, as the night time ionospheric cut-off frequency could be well below 10 MHz [1]. In this paper we present an experimental design of ULW radio array, which operates at the frequency range from 1 to 72 MHz. This experimental array will be applied to make the radio sky observations at the ULW regime, as well as the other astronomical radio observations beyond ULW regime.