Home > HF, Home Brew > NEC Modelling of My 80m Vertical Loop

NEC Modelling of My 80m Vertical Loop

I’ve done some modeling of the 80m delta loop I’ve just built. The aim of the antenna was to provide the best DX performance I could get with my limited resources. The resources amounted to a big roll of wire, a very tall tree and quite a bit of space along my boundary fence.

First the geometry of the antenna.

Apex height around 20m.

Base length 40m.

Base height between 1.5 and 2 metres.

Total wire length 81.99 metres.

Feed 50 ohm coax matched with a 13.1metre of 75 ohm coax acting as impedance transformer

 

Geometry

 

 

Radiation Pattern -Elevation Plot

 

 

3D Plot- FB!

 

FB! around 20 degrees takeoff angle broadside.

By comparison here is the elevation plot at various azimuth angles for a 160m horizontal loop at 80m. This is an idealised version of what I used to have. My 160m horizontal  loop was not a perfect square or rectangle. I will attempt to model it when I get a chance. The takeoff angle of the horizontal loop is about 60 degrees. Much better for normal 80m use which is usually more “local”. This explains why horizontal loops are so popular on 80m.

 

160 m Horizontal Loop Radiation Pattern- Elevation

 

Here also is the elevation plot for my ZS6BKW on 80m. You can see in elevation it is pretty much omni.

 

 

ZS6BKW at 80m

 

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