How Earth-Current Antennas Really Work
Session code: OS6
Oral / Science, Main EuroSpeleo Conference
Dr David Gibson
With cave radio equipment, there has been a trend away from the use of induction loop antennas to the use of so-called earth-current antennas, i.e. long wires grounded at both ends. Both the HeyPhone and Nicola system use this type of antenna. However, the popular explanation for how this antenna works is fallacious. The antenna does not operate by allowing the current to flow in a 'big loop' in the ground, nor is it a 'conduction mode' of operation. In fact, it does not depend, fundamentally, on current flow in the ground at all. The fact that the popular explanation is wrong is important because, if we do not understand how the antenna works, it is difficult to know the best way to use it, nor how to design a better one. In this short talk, without too much emphasis on theoretical physics, David Gibson outlines a more useful model - that of the Grounded Horizontal Electric Dipole.
I am a senior research fellow at the University of Exeter's Camborne School of Mines. Prior to that I spent ten years as research project manager at the UK's Mines Rescue Service. My PhD was in sub-surface radio communications. I am currently the secretary of the British Cave Research Association.