Полная информация об этой и других антеннах размещена на сайте DJ0IP

http://www.dj0ip.de/vertical-antennas/160m-inv-l-on-12m-pole/

( "ANY PORT IN A STORM" - ANTENNA )

I built the following antenna once, last minute, just before a CQWW 160m contest.  I do not have the exact measurements anymore, but it must be adjusted for each different QTH anyway, so this information should be good for a start.