Reading the comments from this engineering forum, losses are assumed to be minimal at the HF frequencies. I would assume at VHF and UHF any oxides might become more of an issue. I totally agree antenna efficiencies are very dependent on height and location. Proper conjugate matching and feed...
My understanding of skin effect, RF will travel on or near the surface of a particular metal depending on the frequency in question. The skin depth at 4 MHz in copper is ~ .033mm. Copper oxides also develop on the surface of bare copper surfaces when un protected. This can happen when...
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. I believe these oxides become semiconductors and have large range of impedances. Due to the nature...
When investigating 600 ohm ladder line, a few questions come up that I hope some of you can answer. It appears this type of feedline can operate with significant vswr because of its extreme low loss characteristics. On the other hand, impedance matching between the feedline and antenna feed...
Ok, When looking anywhere along the feed line that has a mismatch, swr will be present. As a result, "nodes formed as a standing wave on the line are only seen when you insert a meter in the line that cannot distinguish between the independent forward and reflected waves." This concept is new...
I am trying to understand what you are saying about "The sine wave being a special case" in reference to forward and reflected waves. Your theory should hold true for all applications. "Sinewaves are the only special case where backward wave being generated by reflection of forward wave"...
I truly understand that swr is created because of impedance mismatch between feed line and antenna feed point. Any deviation in swr along a feed line is due to the initial loss characteristics of that particular feed line and of course the applied frequency. I certainly did not make myself...
Through my studies, I agree with you that one of the major contributors to swr measurement error is feed line loss. If taking swr measurements close to the source causes lower than realistic measurement data then by the same token, measurements taken directly at the feed point of the antenna...
Engineering has taught us that unequal impedances between feed line and antenna feed point will result in return reflections along the feed line back to the source. The mixing of the forward and reflected waves cause nodes which consist of variations min and max voltages along the line...
Sorry, I guess I didn't really address your question regarding the choice of location for the OCF. When becoming acquainted with this antenna, all the information was exactly that, (rule of thumb) technique. Some information on how and why's but nothing that one could predict with any certainty...
Sorry, I guess I didn't really address your question regarding the choice of location for the OCF. When becoming acquainted with this antenna, all the information was exactly that, (rule of thumb) technique. Some information on how and why's but nothing that one could predict with any certainty...
In my original post, I mentioned that the nice thing about this antenna that it is a multiband antenna (up to 7 bands) only using a wire and a 4:1 balun. The balun is placed at a certain point from the end of the half wave antenna to give you the proper impedance to operate on that band. The...
Since, both antenna radials of the ocf are different lengths, I believe the issue of common mode currents may or may not be important. The common mode currents are supposed to be reduced by a 4:1 current balun which is mounted at the feed point. Many studies have been done stating, this type...