Evolution of the SuperDARN antenna: twin terminated folded dipole antenna for HF systems

SuperDARN is an international network of HF radars dedicated to the study of the Earth´s upper atmosphere and ionosphere. The radars operate between 8 to 20 MHz and thus require broadband antennas for optimal performance. Since the first coherent HF backscatter radar was deployed by The John Hopkins University Applied Physics Laboratory these types of radars have utilised large Log-periodic Dipole Array Antennas. In order to increase directivity and provide a wider feld of view alternative antennas have been tested and developed by various research groups. This process has led to the development of the Twin Terminated Folded Dipole which subsequently is now widely used by the community and has well and truly replaced the LPDA for most new radar installations. This paper provides a brief background of the radar as well as the work that has been involved in developing the TTFD concept. Also presented in this paper are antenna characteristics, direct comparison to its predecessor and pros and cons of the design.