Accession Number:

AD0645233

Title:

AN HF ANTENNA ARRAY ELECTRONICALLY SCANNED IN ELEVATION

Descriptive Note:

Technical rept.

Corporate Author:

INSTITUTE FOR TELECOMMUNICATION SCIENCES AND AERONOMY BOULDER CO

Report Date:

1966-11-01

Pagination or Media Count:

35.0

Abstract:

AN HF receiving antenna array was constructed which is capable of electronically scanning a sector in elevation with a single, narrow, main lobe. It was incorporated into a system designed for ionospheric propagation studies which were to investigate the vertical angle-of-arrival of downcoming radio waves. The vertical broadside array consists of ten 12-MHz to 25-MHz, horizontally polarized, log-periodic-dipole element antennas stacked with uniform spacing on a 152-m tower. The sector of scan is dependent upon the element antenna spacing, and varies with frequency. This sector is from 3 degrees to 51.4 degrees at 12 MHz, and is from 1.5 degrees to 22 degrees at 25 MHz. The half-power beamwidth of the main lobe varies from about 7 degrees to 3 degrees over the same frequency range. The main lobe also of the array was scanned by varying the number of periods in the sinusoidal illumination function which was applied to the array. This scanning was effected electronically at an IF frequency, thus placing essentially no bandwidth restriction due to scanning upon the r-f input circuitry. The fundamental scan-timing frequency was 524 Hz. Each increment of the scan sector was actually scanned twice, however, once in each direction during a scanning cycle. Author

Subject Categories:

  • Electrical and Electronic Equipment
  • Radiofrequency Wave Propagation

Distribution Statement:

APPROVED FOR PUBLIC RELEASE