# Re: Calibrating E-field probes by simulation?

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• Subject: Re: Calibrating E-field probes by simulation?
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• Date: Mon, 04 Apr 2005 12:59:29 -0600
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`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
FANTC.```

```All you would need to do is have the program calculate the capacitance
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?`