. The Bell System technical journal . rN = number of turns in loopA = area of loop in square meters/ = current in loop in amperesD = distance between loop and antenna in metersX = wave-length in meters When the distance between the loop and the receiving antenna is a half wave-lengththe terms in the parentheses become (1 —) which has an amplitude of ( db above unity). Hence the second term increases the total field to dbabove the radiation field at this distance. 130 BELL SYSTEM TECHNICAL JOURNAL indicated by the thermomilliammeter. So long as these were dupli-cated at both en
. The Bell System technical journal . rN = number of turns in loopA = area of loop in square meters/ = current in loop in amperesD = distance between loop and antenna in metersX = wave-length in meters When the distance between the loop and the receiving antenna is a half wave-lengththe terms in the parentheses become (1 —) which has an amplitude of ( db above unity). Hence the second term increases the total field to dbabove the radiation field at this distance. 130 BELL SYSTEM TECHNICAL JOURNAL indicated by the thermomilliammeter. So long as these were dupli-cated at both ends of the path, it was possible to determine the relativevalues of fields at the two ends, regardless of absolute errors. Investi-gation of the behavior of the meter and of the method in general,indicate that the absolute error itself is not large. The map of Fig. 2 shows the locations of the transmitting andreceiving sites used. The tests may be divided into two over water was studied mainly with the transmitter. Fig. 2—Transmitting and receiving locations. located on the bluff at Cliffwood Beach. Measurements on trans-mission over land were made from the transmitter at Deal. Linesradiating from these two points indicate the various transmissionpaths studied. Transmission Over Sea Water For the measurements on propagation over water at 34, 51 and80 mc, the receiving antenna was located at the waters edge, exceptfor a few special tests. The height of its midpoint was varied up to amaximum of about twelve meters above sea level. The data presentedin Fig. 3 show the results with the maximum elevations and verticalpolarization (vertical electric field). This figure shows that the received field was below the inverse ULTRA-SHORT WAVE PROPAGATION 131 distance field that would result from radiation in free space. Thefield strength is more nearly inversely proportional to the second thanto the first power of the distance as may be seen by comparison withthe ligh
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
