Author: E. L. Kilpatrick

Publisher:

Published: 1969

Total Pages: 128

ISBN-13:

Antenna with high gains at low elevation angles are important to long distance HF communication. With application to an 11,070-km circuit between Washington, D.C. and Asmara, Ethiopia, in view, a design for an antenna consisting of four rhombic elements in a nested-tandem configuration was proposed. The overall length of the antenna was 442.8 m (1452.6 ft), the maximum height, 73.2 m (240 ft). Its nominal operating frequency range was from 6 to 19 MHz. Power gain was computed as a function of frequency, elevation angle, and azimuthal direction. Scaled-model measurements, using 200:1 scaling factor, were carried out to verify the computations. Calculations showed the maximum gain to be 26.5 dB at 14.5 MHz at an angle of about 4.5°. The computed performance deteriorated markedly above 18 MHz. The measurements confirmed the computations at the lower frequencies and showed the deterioration in the performance near the upper frequency end to begin at a lower frequency than computer.