Design and Evaluation of an Active Antenna for a 29–47 MHz Radio Telescope Array

The eight-meter-wavelength transient array (ETA) is a new radio telescope consisting of 12 dual-polarized, 38 MHz-resonant dipole elements which are individually instrumented, digitized, and analyzed in an attempt to detect rare and as-yet undetected single dispersed pulses believed to be associated with certain types of astronomical explosions. This paper presents the design and demonstrated performance of ETA's dipole antennas. An inverted V-shaped design combined with a simple and inexpensive active balun yields sensitivity which is limited only by the external noise generated by the ubiquitous Galactic synchrotron emission over a range greater than the 27-49 MHz design range. The results confirm findings from a recent theoretical analysis, and the techniques described here may have applications in other problems requiring in situ evaluation of large low-frequency antennas