I’ve built an 8 radial spider antenna as per the “Your First ADSB Antenna” document that is mentioned elsewhere on the forum. I’m currently waiting for my receiver to arrive so I can plug the thing in and check it out. But I’m wondering, as my antenna will be mounted outside, does anyone know if are any potential electrical or performance degradations if I were to tin the exposed copper of the antenna, or is copper oxidation in the long term not really an issue? Once I get the thing mounted I’m not too keen to go back up to its location, so I’d rather be proactive if it makes sense.
Bare copper will oxidise in air, forming a greenish layer. This will act like a protective barrier to further corrosion of the underlying metal - this is quite unlike iron and steel, where the oxide is flaky in nature allowing the corrosion to continue. There is no reason to tin the antenna elements or paint it with anything to stop corrosion.
You might like to make sure the base of the antenna is well insulated with sealant to stop any rain water bridging the gap. That would reduce reception, and if you have an unblocked DC potential between the ground radials and centre whip (from a coax fed amplifier), you could certainly get some electrolytic corrosion happening. If you are using a franklin type whip which has a phasing stub, then it’s quite important to insulate at least the phasing stub, as rain water will collect in the gap between the horizontal segments and prevent the stub doing its job. That would also reduce reception considerably until it dries out.
