Hi,
I did some research. Using the center frequency of the CB band with the intention of adjusting the 11 meter yagi for a "center" frequency of 28.8 (my point of interest), I have found that I should multiply the overall length of each element (or spacing) by 5.61%. Example: If the overall reflector length is 18.008 feet (11 meters), I should reduce the overall length to 16.998 FT. (1.01 feet difference). 18.008 X .0561 (5.61%) = 1.01 feet
Brad