This is a recording of DF9IC Hennings lecture at the 40th Nordic VUSHF meeting June 9 2018. In the lecture Henning describes some of the ideas behind the 144 MHz antenna design at DR9A. Every station who has worked with multi antennas should watch this lecture. There are a number of outstanding insights and ideas on how to improve your antenna system. It is a real amateur video, so please bear with the sound during the first couple of minutes, it gets better.
A link to the video on You Tube can be found here.