question: sensitive device to measure very small changes in electrical/magnetic fields?

capable of

fields? The

Well, if you don't know which field you want, then how are we supposed to know? Try a ferrite rod with several thousand turns of fine wire on it, and plug it into the mic input of an audio amp.

For a moment there, I thought you were looking for a mirror galvanometer, but maybe not, since you don't seem to be interested in currents as much as fields.

Small changes in large fields? Small changes in small fields? Both electrical and magnetic fields, simultaneously, or would one or the other be sufficient? What changes; intensity, polarization, direction, or ...? Record to what precision? Record with what accuracy? Calibrated or just "as built?" Is it sufficient if the measurements are time stamped and spooled to permanent media or must they be streamed? Should "real time" be synced to the UTC(USNO) master clock (how closely?) or is a precision delta-time sufficient? What sample rate? What is your budget? Does the device need to be UL/FCC/EC/etc. approved? One-off benchtop for curiosity or to gather data for peer reviewed publication?

Numbers.

capable of

fields? The

Calibrated

Should

is

publication?

Rich, you need to make up a standard geek form for this kind of thing. Like

Small changes in: [ ] large fields [ ] small fields [ ] Both

Etc..

Don't forget to include your standard rates for customers. ;-)

I two wood like a sensitive peace of mesurment device that due these things.

Should have a frequency range from 0.01Hz to 453GHz +/- 0.004dB linearity.

Sensitivity for field strength needs to be at least 2.2femtoV/kM.

Hmmm... probably should inlude a discount for anybody that still remembers (and uses) usenet. '-)