The Shielded Transmission Line Method of Generating Standard Fields
Abstract
One of the methods extensively used for the calibration of equipments using loop antennas is the shielded transmission-line method, wherein a wire is erected between two end walls of a shielded room. One end of the conductor is connected to an end wall through a resistance equal to the characteristic impedance of the line, and the output of a signal generator is connected between the other end of the line and the wall. Thus, the wire and shielded room form a shielded transmission line terminated in its characteristic impedance. The loop antenna to be calibrated is placed below and in the vertical plane of the wire. The true field strength at the loop, produced by a known current in the line, can be calculated by applying the Biot-Savart law to the line and all of the images of the line in the ceiling, floor, and walls. When only a few images are considered, as is common practice, it was found that the error in the calculated field can be 20 percent or more. For some typical installations a 5 percent error was obtained when as many as 96 images were considered.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 02, 1954
- Accession Number
- AD1220484
Entities
People
- H. E. Dinger
- W. E. Garner
Organizations
- United States Naval Research Laboratory