Stratospheric VLF vertical electric mono-and dipole antenna tests in 2014–2015

This paper presents the assumptions, executions and results of the three tests of vertical electric mono-and dipole antennas in the Earth's stratosphere, flown using helium balloons to the altitudes between 23 and 30 km in 2014 and 2015. The antennas varied in lengths and presented different technical aspects subjected to the tests (the corona protection, flight mechanics of extremely long flying objects, end weight for stabilizing the flight during the descent phase etc.). All aerials were safely retrieved after the landings. The data gathered during these missions helped to evaluate the basic concept of an airborne vertical electric aerial for Very Low Frequency range; it showed that very long aerials may induce electric charge flow when passing through the cloud layer, need additional weight at their ends to assure safe descent and, when composed of a tape-like structure, automatically move in a helical way, which, with a sufficient antenna length, may in the future enable the design of an elliptically-polarized vertical VLF antenna. The outcomes of the experiments shall be used in the design of a stratospheric VLF transmitter.