Technique for Building and Calibrating VLF/LF Receive Loop Antennas.
Abstract
The strategic VLF/LF submarine communications program involves several VLF and LF transmitter antennas located around the world. The Naval Command, Control and Ocean Surveillance Center (NCCOSC), Research, Development, Test and Evaluation Division (NRAD) is often tasked to baseline the antenna's performance before and after changes are made. One parameter useful in this process is measurement of the VLF/LF transmit antenna's magnetic field strength. The antenna's magnetic field strength provides information on the antenna's effective height, radiated power, and efficiency. Prior to making these measurements, the VLF/LF receive loop must first be calibrated in a Helmholtz coil. Determining magnetic field strength can then be accomplished by taking readings with the VLF/LF receive loop antenna while in the field of the transmit antenna. The voltage induced around the receive loop is measured by a selective level meter (Hewlett Packard 3486C0). Distance from the transmitting antenna to the VLF/LF receive loop is provided using Global Positioning System (GPS) instruments. Antenna current is measured in the helix house of the transmit antenna with a time stamp data recorder. Many of the transmit antenna's performance characteristics can be derived with the above measurements. The purpose of this document is to detail the construction method for building the VLF/LF receive loop antenna as designed by Mr. Don Watt of Watt Engineering. The second portion of this report describes the Helmholtz loop calibration procedure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1997
- Accession Number
- ADA327261
Entities
People
- J. M. Birkett
Organizations
- Naval Command, Control and Ocean Surveillance Center