Not only are Tesla and Amps/meter related, but the relationship is a direct proportion, given a particular medium and a particular magnetic field intensity in the material of interest.
Magnetic Induction vector B (Tesla) = relative permeability (unitless) * permeability of free space (Henry/meter) * magnetic field intensity, H (Amps/m). As for the interference potential of a magnetic field, that depends on the frequency, strength and separation from and geometry of the source. An ADF loop (automatic direction finding) is designed to sense magnetic fields, hence it is susceptible to magnetic interference, from 150 - 1700 kHz, at levels below 1 mA/m. A sensitive circuit near a power supply transformer may pick up noise from that transformer (60 Hz to tens of kiloHertz). This would be on the order of Gauss to hundreds of Gauss (1e4 Gauss = 1 Tesla). The magnetic field surrounding a current-carrying wire conductor could couple into a sensitive signal on an adjacent wire. This would likely be due to several Amps/meter magnetic field. A CRT display is distorted by a field of a few Gauss. If you want to get a little more esoteric, you can consider another class of victims, sensors/receivers designed to pick up low-level magnetic fields. These must be protected from magnetic interference. A magnetic anomaly detector (MAD) invented in the 1960s could measure 13 dBpT at 20 Hz! It could decipher what was being typed on an electric typewriter that was enclosed in a steel shield room. MIL-STD-461 requirement RE04 protected that receiver. A 1950s - 1960s VLF receiver (14 kHz - 30 kHz) was used on submarines to receive a doomsday message to launch a retaliatory nuclear attack. That receiver was protected by MIL-STD-461 requirement RE01. In the bad old days of mutually assured destruction (also MAD), this was an important function and an important EMI requirement. ---------- >From: Rich Nute <ri...@sdd.hp.com> >To: mhopk...@keytek.com >Cc: emc-p...@ieee.org >Subject: Re: Magnetic field monitors >Date: Thu, Dec 16, 1999, 5:01 PM > > > > > Hmmm. Let's see: > > Magnetic field strength is measured in: > > amperes/meter > oerstads > > Magnetic flux density is measured in: > > tesla > gauss > > As near as I can tell, there is no conversion from > one to the other. This would imply they are > separate phenomenon. > > I'm not in the EMC field, but I'm curious as > to regulatory requirements and what "interferences" > such emissions would cause. (I'm presuming both > are regulated.) > > > Best regards, > Rich > > > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to majord...@ieee.org > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to ed.pr...@cubic.com, > jim_bac...@monarch.com, ri...@sdd.hp.com, or > roger.volgst...@compaq.com (the list administrators). > > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
