Thierry, ON4SKY wrote:
"In fact you need to apply the law of physics never the ones of
marketing."

Sage advice.

One of the best guides to vertical antennas for the ham is chapter 9 of
ON4UN`s "Low-Band DXing", published by the ARRL.

ON4UN lists equipment used by some of the best known DXers, but antennas
are listed only by types, not brand names.

ON4UN`s book is probably available in most countries.

Best regards, Richard Harrison, KB5WZI