Topband: Short Bogs

[Gary and Kathleen Pearse]

> If we want to make an antenna electrically longer through cable velocity factor, it can't be done by the insulation slowing the wave inside the shield.
> 
> 73 Tom
> 
In my experience, external insulation (through synthetic covering or frost) lowers the resonant frequency of wire antennas of a given length and height above ground. 

For example, I typically use 453/F as a starter length for insulated wire dipoles...it's higher for bare wire of the same AWG diameter. 

It may not be due to "velocity factor" (not sure of the reason), but it is observable and repeatable.

73, Gary NL7Y