That was a surprisingly good response, even if you did quote it from elsewhere. I like it.
I'm interested in reading that full article, do you by chance have a link or reference?
Just a point or three in addition.
Yes there is a coating that forms on aluminum antennas, and even if you scrub it clean it comes back very quickly. It does act like a dielectric, but it is only a small part of the dielectric. The air, which has close to the properties of a vacuum as far as being a dielectric is concerned, acts as the dominant dielectric as the RF field is not contained withing this coating.
I don't know of any manufactured CB antenna that is made out of pure uninsulated copper. Most of said antennas will be in a fiberglass tube, or wrapped around fiberglass and covered with a coating of some sort if not insulated copper wire. There are a few exceptions, but they are very rare, such as potentially the end piece of a homemade T2LT antenna, or a homemade dipole made out of uninsulated copper wire. You could also include enameled copper wire here. The covering, be it a fiberglass tube, a rubber coating, or whatever, will have the same problem as the coating that forms on aluminum, and typically causes more noise to form to begin with, ara the a99 is an insulated copper wire within a fiberglass tube, and that antenna has been reported by many people to have a serious noise issue. However, the Gainmaster antenna is almost universally reported to be as quiet if not quieter than other antennas, and it to is insulated copper wire inside a fiberglass tube. If you actually have a bare copper antenna of some sort, it is possible to treat it so that it doesn't oxidize and eliminate said problem. I would love to see this copper mobile CB antenna you referred to, do you have any pictures?
While I haven't directly measured the noise floor of my current radio setups, I have access to a friend's Elecraft KX3 ham radio, which has a noise floor of -123 dBm (
as directly measured by a third party source). To put in perspective with the numbers mentioned above, that is 0.000001 microvolts. It is one of the more sensitive receives of any radio on the market (or at least was not to long ago). It sounds the same through a dummy load as it does through his aluminum antenna on a quiet night... His setup, as well as mine using a first or second generation RCI 2950 (I have both versions), or a Galaxy DX-55HP (whichever I feel like using at the time) the static can be so low that at my normal volume levels it simply does not exist (I've actually forgotten the radio was on and accidently left it on before when monitoring a frequency, then woke up later to mysterious voices in my house). I do not know the specific noise floor ratings of my three radios. Therefore, as I mentioned above, in my experience, I don't see an aluminum antenna itself affecting the noise floor.
I am willing to say that there is room for error in my judgement on this as this was judged by me listening for the strength/loudness of the static noise. I can't guarantee my hearing over anyone else's, and have to call that subjective as on some level our minds tend to hear and see what we want/expect them to hear/see. I've learned the hard way that our senses are not the end all and be all of accuracy, and more often than not our brains play more of a roll than just interpreting said results. Or, to put it simply, there is no accuracy using our senses, at least not at the level needed for this type of test. The only thing I can tell you for sure is that when it is quiet out, none of these radios s-meters registers the noise in the silence, and I can often hear signals in the distance that also don't register on the radios s-meters, and I can talk back to them. Short of building an attenuator to get a signal to match your 0.3 microvolt number into a radio I also have no direct way of knowing for sure what s-unit reading said radios will actually show for such a measurement as, as I mentioned at least once above (and I'm sure we all know by now), said meters are notoriously inaccurate.
Hmm, longer post than I expected... Goodnight.
The DB
