Jackson Richter said:
In my search, I have been looking for any data that might explain the RF resistance from 3 to 30 MHz range of the two basic types of copper oxides that form on the outside of bare copper wire.
You should consider humidity of the atmosphere as a variable. The thickness of the surface dielectric oxide layer determines the velocity factor on the wire, but that effect is small because the layer thickness is small. With time the oxide may be converted to a copper acetate which has more stable but different dielectric and hygroscopic properties as it matures over time.
The Velocity Factor of exposed bare copper wire is close enough to 1.00 for most practical purposes unless you are modelling the precise radiation pattern of long traveling wave antennas. Thirty years ago I measured the VF of a single strand of weathered beryllium copper wire as 0.997 ; (Note: dust from beryllium copper is carcinogenic). The catenary sag of a long wire between supports is a more confounding variable than is VF at HF.
Jackson Richter said:
I believe these oxides become semiconductors and have large range of impedances.
Yes, copper oxide is a semiconductor, but that is not important. It is only when a connection is made that pinches, but does not cut through the surface layer, that any harmonic generation can occur. Zinc oxide is also a semiconductor, so the same is true of galvanised and zinc flashed conductors.
Remember that a lose terminal can generate harmonics. Use stainless steel clamp bolts with dielectric grease to keep the water out of the metallic contact.
There may be microphonic wind noise voltages generated between multi-strand conductors that are not present on a single conductor. Single conductor wires vibrate more in the wind than multi-strand, which tends to ameliorate that problem.
Copper work hardens. If you use a single solid conductor you need a short rubber tube near the end as a damper to prevent wind vibration fatigue of the wire. Wire insulation can achieve the same reduction in vibration, but it significantly reduces the velocity factor.
Jackson Richter said:
Due to the nature of skin effect at RF along with the combination of the oxides, will antenna efficiencies be affected and if so how much?
Antenna efficiency will not be affected by the oxide. Much greater losses arise due to variation in height, or distance from support structures. Failure to taper the effective wire diameter to maintain constant transmission line impedance along the wire causes much greater losses due to progressive reflection. Tapered cage dipoles are often needed to make efficient HF antennas.
If you want low losses you must learn to analyse antennas as transmission line inductors in their capacitive environment. Analysing the impedance of a traveling wave antenna is a good start. Resonant antennas can become more complex.
