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Excerpt from The Field Radiated From Two Horizontal Coils Mr. 'willoughby proposed the use of an antenna consisting of two horizontal coils, one placed somewhat above the other, the current in one coil owing in the opposite direction to that of the current in the other. The current was intended 'to be of a fairly high radio frequency, such as is ordinarily employed, in radio communication with airplanes, so that signals could be received with an ordinary radio receiving set. In general, it was believed that the waves would radiate in the form of a beam or inverted cone above the antenna. Experiment showed this to be true, signals being received on the airplane only when it was nearly above and in the immediate vicinity of the transmitting antenna. To determine from theoretical considerations the nature of the radiated field and the region over which signals can be heard at various heights above such an aerial, 'the following calculation was made. The calculation justifies the belief that the radiation would form a beam in the form of an inverted. Cone above the transmitting antenna. The results of the calculation are expressed in inverse powers of the distance from the transmitting antenna. 'the lowest power gives the radiation component of the field. The next higher power may be looked at as a first approximation to the induction component. In the final formulas it is always assumed that the dimensions of the transmitting coils and the distance between them are small in comparison with the wave length used. However, it has been made sure by additional computations that the directional properties of the radiation do not depend on this approximation within a wide range. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works."