The Analysis of Experimental Deployment of IGLUNA 2019 Trans-Ice Longwave System

Abstract

An experimental longwave system operating in the broadcasting spectrum with horizontal magnetic loop transmitting antennas is presented as an element of simulated lunar astronaut mission of the IGLUNA program of Swiss Space Center (ESA_Lab demonstrator) in June 2019 on the Klein Matterhorn glacier in Switzerland. The parameters of the antennas, the environment, the transmitter design, and propagation tests are presented. The best-suited propagation model is developed. As the system, using low powers, provided coverage of maximal distance of 2077.06 km, a single radio station of this type would cover about 36% of the Moon’s surface and allow in situ ground-penetrating research.

Risk Assessment and Experimental Light-Balloon Deployment of a Stratospheric Vertical VLF Transmitter

“…The apparent frequency decrease for a lower-frequency radio emitter elevated at a substantial altitude have also been observed in [ 54 ], where a most convenient ground-positioned antenna was tested—an HML (horizontal magnetic loop) positioned on the top of the Klein Matterhorn Mountain (~3.9 km above the mean sea level) in Switzerland, operating as an inductive device at the center frequency of 270 kHz within the 9 kHz bandwidth. Apart from the specific formula describing the propagation of such a signal (adapting the popular ‘sum-of-square-roots’ formula by Vviedenskiy [ 52 ]), a dependence on the frequency has been found in the propagation curves provided for different frequencies by the CCIR—an equally achieved range from a ground-based vertical-antenna emitter has been reported for the 2× lower frequency than the one actually used in the HML tests on Klein Matterhorn.…”

“…electrical power consumed: 15 mW) below 2.5 mW/m 50 m away from the HML’s center, with no external reports received. Even for the augmentation of the transmitter’s power to match exactly the level reached in [ 54 ] (but for the same modulation index), the ground-based HML in this case is not expected to surpass the mountain-elevated HML in signal coverage.…”

“…The difference in the signal coverage between the same type of antenna, i.e., the HMLs positioned on the mountain and on the ground, is natural. Tests conducted in 2021 with the employment of the HML of the parameters analyzed in [ 63 ], showed the decrease of the emitted signal on 198 kHz (signal type: A3E-SC, modulation index same as in [ 54 ], max. electrical power consumed: 15 mW) below 2.5 mW/m 50 m away from the HML’s center, with no external reports received.…”

“…The radiation resistance, calculated for a symmetrical dipole of equal electrical length and effective length of 200 m, reached 0.14142 Ω [ 52 ] (short dipole << emitted wavelength); the calculated tuning inductance for this antenna at the given frequency reached 278.013 mH [ 52 ], which was divided in half and symmetrically introduced into the upper and lower parts of the antenna with the use of small ferrite-core inductors. The transmitter employed the adapted design previously used in the high-altitude experiments in the IGLUNA program [ 53 , 54 ] (with no modulating transformer), with the power amplifier based on four POWER MOSFET transistors with elaborated heat sinks [ 43 ], excited with a switching-circuit-based frequency generator tuned by an RC circuit (which proved to remain acceptably stable in glacier-based field campaign of [ 54 ]). The main power source was constituted of a 56-V battery pack which allowed the transmitter to function during the entire flight.…”

“… The apparent frequency decrease prediction function plotted for the LF/270 kHz case from [ 54 ]. The formula is based on the maximum obtainable signal coverage from the HML elevated antenna in reference to the ground-based antenna from RKS Topolná (the main transmitting site on 270 kHz [ 62 ]).…”