The 468 comes in to play as dipoles have what is called an end effect of 
around 5 percent.
I'm not sure where the formula for the loop comes from but if you're 
figuring say a quarter or half wave stub, you use 300 meters which is a 
full wave length and the speed of light.  To convert this, take meters 
times 3.28 so 984 over frequency gives youa full wave length.  for a 
quarter wave stub, for example, divide this by 4 and then that number 
times the volocity factor of your coax.

Way back when I was selling a lot of cb rigs, and people were running 
quarter wave whips, 102 inches long.  These ghings would pick up enough 
static here in a dirt storm, you could lay the pl259 on the dash and 
sparks would jump from the center pin to ground.  Needless to say, this 
was hard on fet transister front ends, so her was my fix.  I would divide 
984 by 27 mhz, which comes out 36.444 and 36.44 divided by 4 for a quarter 
wave in feet is 9.111.  The coax I used which was rg58 had a volocity 
factor of around .7 as I recall, so 9.111 times .7 is 6.377 feet.  I'd 
make this stub, short one end and put it on a t connector on the radio 
with the antenna to the other leg.  It was a dc short, but as a quarter 
wave looks open at its frequency, the radio didn't know it was there. 
Worked like a champ!!

73
Butch
WA0VJR