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Re: Calibrating E-field probes by simulation?

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 07:48 AM 4/4/2005, you wrote:
Original poster: "Steve Conner" <steve.conner@xxxxxxxxxxx>

Hi all,

I was just thinking about ways of measuring the output voltage of a coil.
E-field probes like Terry's planar antenna are a nice solution but the
problem is how to calibrate them. It struck me that if you were to use a
probe with an easily modelled geometry (a small toroid or sphere?) then the
calibration could be done using a finite element modelling program like

All you would need to do is have the program calculate the capacitance
between your coil's topload (plus some fraction of the secondary self-
capacitance I suppose?) and the probe. The division ratio of the probe is
approximately (capacitance between probe and coil)/(capacitance between
probe and ground including cable and scope input cap)

One can get an empirical calibration by connecting a suitable power supply/source to the coil and measuring the output of the probe.

The trick is in getting a measured voltage on the top load, at the desired operating frequency.

At low frequencies, the field distribution will be different because of the different inductive impedance along the secondary.

At high frequencies, you have the same measurement problem.

How about something where you make measurements at several distances?