Electromagnetic Field Probes.
Abstract
This report summarizes investigations directed to the development of probes and techniques for measurement of electromagnetic radiation in shielded enclosures over the 20 to 200 MHz frequency range. Emphasis was placed on (1) development of lossy material for use in reducing enclosure Q, (2) fabrication of frequency-scaled model enclosures for high-Q and low-Q tests, (3) development of frequency-scaled probes, (4) collection of coupling data for high-Q and low-Q enclosures and comparison with free-space (anechoic chamber) data, (5) measurement of interaction effects between simple antennas and shielded enclosures, and (6) investigation of probe coupler and preamplifier characteristics. Experimental data for frequency-scale models of 8 x 8 x 12 foot enclosure indicated that resonance and wall coupled effects could be considerably reduced if the Q of the enclosure is reduced to Q < 5. Reduced Q was obtained by coating the inner walls of the model enclosures with a graphite-spackling compound mixture. Measurement of the terminal impedance of selected probe antennas shows that enclosure-to-probe interactions can be reduced to acceptable levels if the probe dimensions are kept to less than wavelength/10 at the highest frequency of interest and if the probes are maintained at greater than wavelength/10 from the walls of the enclosure. Preliminary studies of active couplers and preamplifiers show that such devices may be useful for measurement of electromagnetic radiation in shielded enclosures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1972
- Accession Number
- AD0901529
Entities
People
- D. W. Robertson
- J. L. Birchfield
- R. D. Wetherington
- W. P. Cooke
Organizations
- Georgia Tech