Hi Ed,
Your conclusions based on your modelling are completely consistent with my practical experience and modelling. The most likely degradation is a T-top between 60 and 75 feet long degrading the front-to-back ratio, pattern and gain of a 40 meter Yagi when its main beam points into a T-top that's roughly parallel to the 40 meter Yagi elements. Only the 40 meter Yagi is affected, especially if the Yagi is within about 400 feet of a 160 meter T-vertical with a 60-75 foot T-top. The 160M T-vertical is not affected. How to avoid degradation of a 40 meter Yagi? - avoid T-tops between 50 and 75 feet long, or - use an inverted-L rather then a T-vertical All of the above is based on actual degradation of my 3 element 40M Yagi by a 160M T-vertical 40 years ago. Changing the T-vertical to an inverted-L returned the 40M Yagi to its prior excellent performance tks 73 Frank W3LPL ----- Original Message ----- From: "Ed Sawyer" <sawye...@earthlink.net> To: topband@contesting.com Sent: Friday, February 28, 2020 2:47:34 AM Subject: Topband: T Top Verticals and yagis Frank had brought up the interaction of certain T top loading wires and the possible interaction with yagis. I played around with modelling on this and found that just as Frank said, there is interaction of T top wires and yagis. One thing I found was that if the wire is in the front pattern of the yagi it is much more influenced if the wire is the front 1/3 portion rather than the sides and back of the yagi. I didn't find meaningful distortion in the back area 200 ft away but closer than that and approaching the front, and there was definite distortion. Interesting topic Frank. Ed N1UR _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector