This telescope is no more existent. I am using it here as a good example of a telescope which uses a combination of beam forming and synthesis-imaging techniques. This was a fully steerable deca-metric array. This was a array of conical spiral antennas, km by km. It had the best sensitivity in the MHz to MHz. Both its operating frequency and beam position were adjustable in less than ms (see Erickson et al. 1982).
The basic element is a long spiral element utilising eight wires wound around a support system that consists of eight parallel filaments. Each element is circularly polarised with a diode switch at its apex that rotates its excitation and thus adjusts its phase. Steering of the array is accomplished by putting a linear phase gradient across groups of elements, called banks. There are 16 banks in the m arm and banks in the m arm. The output of each bank is brought separately to the central observatory building.
A separate receiver channel is attached to the output of each of the banks. Each channel employs a superheterodyne receiver7.4 to down convert the signal to MHz. The MHz output of each of the receiver channel is sampled at a frequency of MHz digitally delayed and then cross-correlated in a channel two-bit three level complex correlator. An off-line processor removes the fringe rotation7.5 introduced by the earth's rotation and integrates the data for periods up to minutes. A Fourier transform then produces a map of the area of the sky under observation. These maps may be averaged to effectively integrate the signal for periods of hours.
It's total collecting area was . The synthesised beam at MHz had a width of at the zenith. The confusion limit of the telescope was around Jy. It produced picture elements in a field of view roughly .