1/4 wave whip antennas

Using the 1/4 wave formula 234/F(Mhz) a 102" whip was cut down to the correct theoretical length for 52 Mhz. To my amazement, when placed on the rear mount, the resonant frequency was 56 Mhz. I added an additional 6 inches to the base (spring and quick disconnect) and the resonant frequency dropped to 53.75 Mhz. To get the frequency to 52 Mhz, I’d need to add just under 12 inches in total length to the whip.

This indicates the 246/F(Mhz) at 4.73 ft formula is closer - but not quite adequate - to estimate the real world length of a 1/4 wave rear mount whip antenna. The required length was calculated  with a correction factor using the formula 280/F(Mhz), resulting in a length of 5.4 ft.

Interesting, no?