Simple topband toploaded vertical

I got many requests about how I put together my 18 meter topband vertical so here is the recepie:

SM0MDG 160m toploaded vertical

SM0MDG 160m toploaded vertical

The base of this antenna project is the 18 meter spiderbeam mast using three levels of guying where the upper guys also serve as the top hat. This makes it easy to deploy the antenna for temporary use but the antenna is also robust enough to survive the top band season.

As the top part of the glass-fibre pole is weak, the hat has to be attached two sections down from the top, at around 15 meters height. I am using three 15 meter long 1 mm enamelled copper wire for my hat. That is enough for full legal power, and the wires are strong enough for guying.

The vertical antenna wire is 1.5 mm insulated multi cord running from top to bottom. I use a very simple ground system of two elevated radials which works fine in my location but you might want to consider a lager number of radials on ground. The antenna measures around 17 Ohms so I feed it with using an un-un of this type wound on dual FT240-61 cores. In addition to this I have a common mode choke of RG-213 wound 18-20 turns on a 10 cm plastic pipe to suppress RF in the coax shield.

You will find a PDF document with the drawing here.

73 de Björn, SM0MDG