Radio direction finding at 1.67-meter waves

Abstract

Different antenna systems were tested for both horizontal and vertical directivity on this wavelength at distances of from 7 to 30 miles. The antennas used in these experiments included parabolic antenna, V-type, double V-type, Adcock antennas, etc. Using an Adcock antenna the azimuth of the incoming electromagnetic wave can be defined within one half degree accuracy, and with a slight modification of the receiving elements to form a horizontal H antenna, the vertical angle of the incoming wave can also be obtained with the same degree of accuracy. The former antenna can be converted into the latter by mechanical means within a few seconds and thus both vertical and horizontal angles can be measured with the same antenna set-up. With the antenna one and a half wavelengths above the ground and with the ground surface homogeneous in the immediate vicinity of the receiving antenna, the direction of the incoming electromagnetic wave coincides with that of the transmitter emitting the wave, with in the same accuracy of one half degree. Deviations from the true directions at different locations and at different times were observed. A simple theory of reception of the horizontal H and the Adcock antennas were also given. The receiver used for this experiment is a superheterodyne receiver specially designed for this purpose using a resistance-coupled I-F ampligier. It is very stable in operation and has ample sensitivity.