Antenna length thoughts

Antenna length for the WSPR tracker

So, there are a few factors that impact the ideal length of the antenna for the WSPR tracker.  The classic wavelength formula is:

wevelength = 984 feet / Frequency in MHZ

This is adjusted by the velocity factor of the wire, which is also impacted by whether or not the wire is insulated.  I found several resources discussing wire length.  Conventional wisdom seems to be to adjust by between 4-5%.  W7NAT likes 5%.  This would be for ground-mounted antennas.

However, we're using very thin wire,  and we're in free space.  I'm going to try a full 1/4 wave with no adjustment.

Antenna scenario	Element length (inches)
20m 1/4 wave dipole for 14.0971.  No Adjustment.	209.4
20m 1/4 wave dipole for 14.0971.  4% adjustment for insulation.	201.0
20m 1/4 wave dipole for 14.0971.  5% adjustment for insulation.	198.9