ELF Noise Observed in the Vicinity of Large Jet Aircraft.
Abstract
Measurements were made of the electromagnetic fields generated by a KC-135 aircraft in a frequency range of 20 to 200 Hz. The measurements were made using an array of four parallel plate electric field antennas and one ferrite-core magnetic field antenna placed on and near the aircraft; the noise was measured during powering of the engines to as high as 90% of full power while the aircraft was held in place on the ground. The measured noise was complex and difficult to interpret but could be divided into two parts, one arising from various electrostatic sources and the other from vibrations of the antenna on the airframe. The peak electrostatic noise component varied between -35 dB relative to 1 v/m square root of (Hz)(dBE) and -10 dBE, depending on antenna location. These amplitudes are 40 dB to 65 dB greater than typical atmospheric noise. The largest vibration-related component was +8 dBE. The vibration related noise probably is caused by variations in capacitance between the antenna and the airframe due to vibration of the mounting rather than vibrations within the antenna. Aircraft-generated noise of these magnitudes will make reception of the transmitted ELF signal difficult at all ranges from the transmitter. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1977
- Accession Number
- ADA057685
Entities
People
- Joseph A. Goldstein
- Robert J. Dinger
Organizations
- United States Naval Research Laboratory