LF: Antenna calculation

["mv tsi" <mv.tsi@laposte.net>]

Hi Group,

I am interesting to calculate my antenna "efficiency".

But How?

You can see the GIF file.

For information I have water at 6 meters down.

I'll used a variometer but how to attack it?

directly under the TX  or making some turns arround the vario?

Is the second possibility interesting for 50 ohm feeder?

Thanks for you assistance.

Marc F5MAF

PS I hadn't seen anything on 71 KHz band Yesterday.