As promised I contacted the publisher they told me that if you want to contact Jan Dries they will pass your message to him.
Here is the e-mail addres firstname.lastname@example.org
Just address your letter to Mr. Jan Dries.
English is not a problem I hope they forward your message and that he responds.
A word of caution: I searched for the lecherantenna its used for dowsing also to find geopatic radiation.