best or acceptable wire size for dipole

[M3KXZ]

Re the SS 316, I've just taken the resitivity figures and run them for full size half-wave dipoles in EZNEC. For 3.5MHz, copper wire of 0.5dB better than 316 grade stainless steel, at 7MHz copper is 0.35dB better, at 14MHx copper is 0.25dB better and at 28MHz copper is 0.1dB better. This is comparing copper before it has corroded against 316 grade stainless steel. The differences wouldn't be noticeable.

Interestingly though, I understand that the losses with 316 SS would be greater as wire length increases, and would also be greater as frequency increases. In the case of full size half-wave dipoles, the losses through increase frequency are offset by the fact that the wire runs are shorter. But strangely, when I model a 44ft doublet, which is short on 7MHz, the loss of SS 316 wire vs copper is much higher - about 0.8dB (compared with 0.35dB difference at 7MHz for full size dipole).

[VK2TIL]

Interesting work!!

I forgot to say that my calculations were done for a frequency of 100 MHz.

The extra loss in the short antenna might be simple ohmic loss; that implies more current flowing.

But I don't really know.

[M3KXZ]

all food for thought init! I need sleep now - got to be up with the birds to go out doing tree and hedge work...

73, and happy holiday!

Pete

[M0DSZ]

Seeing as you are in the UK, I would suggest, as I always do, 4mm squared, stranded, PVC-covered (conduit) wire in grey which won't cost you much per 100 metres.
It is remarkably strong and, provided you reinforce the ends where vibration nodes take place, will stay up for years. Don't pull it "twang-tight" either, just a little slack.