Conjugate Magnetospheric Transmissions at VLF from Alaska to New Zealand.

A very low frequency (VLF) magnetospheric transmission experiment was conducted between Port Heiden, Alaska, and Dunedin, New Zealand, during August 1972. The transmitter was located at Port Heiden (56.93°N, 201.42°E), and the receiver was located at Dunedin (45.87°S, 170.22°E). A mobile VLF transmitter developed by the U.S. Navy for shore-to-submarine communication was used for the experiment in Port Heiden. The unique feature of this transmitter is the antenna, which is a conducting cable suspended by a helium-filled balloon. The original system was designed to operate with the balloon at altitudes up to 3000 m. The size of the balloon used in this experiment was limited by available resources, and the maximum altitudes possible were between 1200 and 1500 m. Vertical radiators of these dimensions are required because at 10 kHz, the wavelength is approximately 30 km so that antennas of sensible dimensions are much shorter than a wavelength and hence are poor radiators.