High Frequency Radio Emission and Reception by Forest Trees and by Helicopter Using Hybrid Electromagnetic Antenna Couplers.
Abstract
NTS, Coupling circuits, Trees, Aircraft antennas, Helicopters, Antenna radiation patterns, High frequency, Forests, EnvironmentsHEMAC(Hybrid Electromagnetic Antenna Couplers), Hybrid electromagnetic antenna couplersMeasurements by helicopter of 5.750 MHz radiation patterns from closely-spaced hemac-coupled forest trees and from a 24-foot high marine whip antenna at the same forest site show that the directivities of high-frequency skywave radiation from the trees and from the whip are controlled by the local forest structure. By operating these closely-spaced trees as a phased twin-tree XMTR array, control over the elevation of the maximal radiation lobes is gained by the radio operator, while the local forest structure remains in control of the geographic azimuth angles of the radiation minima. Analogous to the exploitation of forest trees as antennas, the body of the helicopter was used as an antenna by means of a hemac wrapped around its tail section. (Modified author abstract)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1973
- Accession Number
- AD0773909
Entities
People
- Kenneth J. Murphy
- Kurt Ikrath
- William Kennebeck
Organizations
- United States Army Communications-Electronics Command