[Antennas] Fat rugged dipole?

Wed Jul 27 00:14:50 EDT 2016

I've been running some number for a dipole at 312 MHz.
Using 468/f, I get 1.5', too large for my installation and that's for a 
"wire" antenna.
I need something rugged to avoid possible damage grom vandals, and most 
likely, large animals. No problem with a couple of elements turned out of 
solid aluminum looking like a couple of small soup cans...
I know a radial can be shortened to an extent if it's fattened...
Generally, for an element of 4" or 6" length, how fat would it need to be to 
be resonant at 312 MHz?
Is there a resaonably easy to use calculation for such things?
Thanks.
Kurt