Electromagnetic Field Probes.
Abstract
This report summarizes investigations conducted during the fourth quarter of a program directed to the development of techniques and probes for measurement of electromagnetic radiation in shielded enclosures over the 20 to 200 MHz frequency range. Emphasis was placed on (1) anomalous coupling modes in low-Q enclosures, (2) interaction effects between shielded enclosures, simple antennas, and complex radiating sources, and (3) study of electrically-small, active probes. Coupling data obtained in the low-Q model enclosure indicate that coupling modes exist in the low-Q enclosure which are significantly different from the coupling modes that exist in the high-Q enclosure. Two possible causes for these anomalous coupling modes were suspected and both were investigated. The results from the experiments indicate that the anomalous coupling modes are a result of the smooth wall surface and reduced enclosure dimensions of the low-Q enclosure. A measurement program to determine the influence of a shielded enclosure on the characteristics of an electric-field probe or radiating source was initiated during the second quarter. During this report period, additional measurements were made on a 75-cm dipole antenna and on a simulated equipment case to determine the enclosure effect on a more complex radiating source. An analysis was made to determine if the required emission measurements can be satisfactorily performed in a shielded enclosure with an electrically-small, active probe. This study included consideration of the minimum field intensities that must be measured, the length and impedance of the short antenna probe, and the sensitivities of typical noise and field intensity meters. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1972
- Accession Number
- AD0904994
Entities
People
- J. L. Birchfield
- R. D. Wetherington
- W. R. Free
Organizations
- Georgia Tech