detection pattern of a concentric

[Koala]

Just been testing a concentric with a horizontal coin


The detection pattern does not seem to be a cone but a cylinder rising up from the Rx windings and fairly flat across the Rx diameter.


Is this just a coincidence with this particular coil or would increasing the Rx diameter increase the coverage. Does this have a negative effect on depth.

[Davor]

Seek some Aziz' simulations, it is all there.

[ivconic]

https://www.youtube.com/watch?v=8llkHQtaOlg

[Koala]

Seek some Aziz' simulations, it is all there.

Seen the sims of the Tx and its field


Don't understand how the Rx and targets affects the results


For example a coin on its edge has virtually no sensitivity in the centre of the coil and only detected directly above the Rx windings. Where as the same coin flats to the coil is most sensitive in the middle.



I was wondering what advantages there are with a smaller Rx diameter as per modern Tesoro coil or large Elliptical as per some Fisher Quicksilver coils. Over a standard Rx 50% less than Tx

[Davor]

Real life targets may assume any size or orientation. What is helpful in grasping what's going on is imagining or measuring typical or special cases, and extrapolate from there. A coin lying flat may be observed as a small coil lying flat. Its response is very much the same as a same size coil with the same orientation. Also the same coin on its edge is like a perpendicular coil, hence very little current is induced.

The most important thing about coil size vs target size is the ratio of their areas. It all makes sense.

You don't have to know the Biot Savart law to make sense of it all.

[Koala]

Done some testing with a cut half coin on its edge.

concentric

Horizontal 8.5" maximum depth on the centre
On edge. 7.5" maximum depth over the Rx windings and no sensitivity in the centre.


DD the same except maximum depth on coin on edge is at the heal and toe of the coil.




I take it by making the Rx smaller in a modern Tensor concentric then pinpointing is improved.

[Qiaozhi]

I take it by making the Rx smaller in a modern Tensor concentric then pinpointing is improved.

I think it's for two reasons:
1) To improve pinpointing (as you stated above).
2) To increase target detection in trashy areas.

Point #2 is probably the most important reason.