Radiation Characteristics of the TACAMO-IV-A Airborne VLF Transmitting System
Abstract
The Naval Research Laboratory and other Navy laboratories cooperated to conduct an investigation to determine the vertical effective radiated power (VERP) of the TACAMO-IV-A airborne VLF transmitting system. The mobile nature of this system required special techniques for this investigation. A series of comparison tests was made in which the TACAMO-IV-A was located near the ground-based transmitting station NAA at Cutler, Maine, and operated at 18.2 kHz, a frequency close to that of NAA(17.8kHz). Simultaneous field-strength measurements of special transmissions from the two transmitting systems were made at great distances. Precise measurements of the NAA radiated power and a comparison of the received field strengths were used to determine the TACAMO-IV-A VERP. This report is intended as an analysis of the results of the VERP measurements with particular emphasis on its application to the prediction of communication coverage to surface or subsurface receiving systems. The results show that the system design objective of an average VERP of 100 kW was obtained. However, optimum communications from the TACAMO systems are achieved while flying in a tight, 2- to 3-minute-orbit pattern. Even under optimum conditions the received field strengths from the TACAMO-IV-A and other TACAMO systems have an orbit-produced periodic fluctuation of 3 dB. Since this fluctuation occurs at least once each orbit, the effective VERP for communication coverage predictions for the TACAMO-IV-A is 71 kW, which is 1.5 dB below the average 100 kw.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 12, 1971
- Accession Number
- AD0518416
Entities
People
- Edward E. Barr
- William E. Garner
Organizations
- United States Naval Research Laboratory