[Antennas] Cubic Quad Info

[Raymond W Brann]

Greetings, I've been looking at a couple of the online Quad Calculators.

Something troubles me with the results and wonder if it's me or the
calculator.

If I enter a Center Freq of 21.255 then look at the results, the
Director #2 is 533.94 In
If the online Calculator is using as stated 960 / F (MHz)
Should it display 541.99 In ??

Looks like it's using 945 / F (MHz)

Anyone know what I'm doing or thinking wrong?

Thanks
Ray