Separately Detect Electric and Magnetic Field Remotely?

[jetwash]

How can I separately detect electric and magnetic field remotely?
I am aware of the Faraday Effect, but because the magnetic field is so weak I won’t be able to detect the polarization change.

 

[VEBill]

You'll have to provide much more information if you expect to get any useful advice.

DC?
AC? Frequency? Frequency range?
What are you trying to attempt?
What polarization change? H/V, RHCP/LHCP?
What do you mean remotely? How far away?

 

[jetwash]

The Operating Frequency options I am needing are 902-928 MHz ISM (Industrial Scientific Medical) band or up to the 2.400 GHz to 2.500 GHz ISM band.
I am trying to attempt is to SEPARATELY detect and measure the electric and magnetic field remotely. At a distance up to 5 miles or more.

 

[IRstuff]

Not even clear that you can measure them together at that distance. What is the application? Unless your source has power output comparable to a cell tower, you're going to have some challenges.

TTFN
faq731-376

 

[VEBill]

I detect that several basic concepts are in need of straightening out.

The impedance of free space (Wiki) is the hard and fast relationship of electric and magnetic fields (provided that you're measuring in the far field). Measuring them "separately" is essentially a flawed requirement (unless I'm misunderstanding you). Measure the RF field strength and the E/H fields can be calculated on the back of an envelope.

Top post mentioned the difficulty of detecting polarization changes. Invalid. Detecting the polarization is almost as easy as detecting the signal. Although detecting CP would be another experiment.

As stated by IRstuff, to cover five miles you'll need a proper medium power transmitter (not normally permitted in these typically unlicensed bands), or dedicated and ambitious experimenters with high gain antennas.

 

[VEBill]

Are you trying to measure or detect some Faraday effect polarization rotation through five miles of normal atmosphere?

 

[jetwash]

I am trying to detect Telluric Currents. They are very faint.

 

[VEBill]

...so you're planning to use an essentially non-existent effect to measure a faint signal?

If telluric currents could muster enough Faraday effect to be even hypothetically detectable, then the Earth's baseline magnetic field would have humanity's RF signals spinning like windmills. We would have noticed that.

 

[IRstuff]

As far as I know, the flows that create the time-varying components of the Earth's magnetic field are all quite low frequency, i.e., on the order of hours.

TTFN
faq731-376

 

[jetwash]

Inductance method could be used, using wires in the ground. And shooting a beam and bouncing it off a plate for a return signal could be used also. Although, that is not my goal. I am trying to find someone who has experience outside of the box for some advice on a remote system that would work without wires in the ground or plates to bounce the signal off of.

 

[IRstuff]

Just how large are these currents? And why are they such high frequencies?

Commercial magnetometers are able to measure variations in the Earth's magnetic field from low-Earth orbits.

TTFN
faq731-376

 

[VEBill]

Faraday effect (Wiki image)

Red signal is the ISM RF signal (902-928 MHz, or 2.4-2.5 GHz), V is the Verdet constant for the material, B is the delta magnetic signature (at about 100 ppm of the baseline), and the polarization rotation angle ß (basically zero point zero zero zero zero zero zero zero...).