TopBand: Top-loaded vertical

[Terry George]

This question applies to an 80m vertical - but this reflector is 
probably the most likely to provide an answer !

   I am playing with a 38 foot vertical , with a loading coil about 
10 feet from the top , and three wires each ten feet long forming a 
capacity hat immediately above the coil. These are incorporated into 
nylon guys and slope down at maybe 30 degrees to the horizontal.

   The antenna is ground isolated and fed against a reasonably 
substantial buried radial system ; with a matching coil across the input.

   Is there a recognised rule to determine the optimum length of the 
capacity hat wires - and also would increasing the number of these 
wires from three to -say- seven improve the efficiency of the antenna 
to any significant degree ?


   Please reply direct and I will summarise to the reflector if appropriate.

            Many Thanks

Thanks to all who replied. The general opinion was to remove the top 
loading coil and increase the number (and / or length) of the top 
wires to resonate the vertical. These wires should be as close to the 
top of the vertical as possible.
A general rule to make the loading wires 30% of the antenna height 
was mentioned.

                     I have carried out these changes , the top wires 
are now about 15 feet long and one metre from the top of the rod. 
Lengthening the wires comfortably resonated the antenna without need 
for the loading coil, and it seems to work pretty good ! 



                      73s Terry

                

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Terry George . G4AMT  - On the edge of the Atlantic at Sennen Cove, Cornwall.






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