What is the approximate physical length of an air-insulated, parallel conductor transmission line that is electrically 1/2 wavelength long at 14.10 MHz?

Explanation

A full wavelength at 14.10 MHz is 300 / 14.10 = 21.3 meters, so a half wavelength is about 10.6 meters. Air-insulated parallel conductor line has a velocity factor very close to 1, so the physical length is essentially the same as the free-space figure.