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#10
June 13th 06, 06:00 PM
posted to rec.radio.amateur.antenna
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Noise level between two ant types
Cecil Moore wrote: wrote: Cecil Moore wrote: When I lived in the Arizona, clear-sky wind-driven charged dust particles transferred lots of energy to my bare-wire G5RV. It caused arcing whether the outside braid was grounded or not. It only happened when the wind was blowing and the humidity was very low. But that effect is common no matter where we live. As I've said several times, a high dipole here for 160m charges enough to knock you on your rear on a calm sunny day if the coaxial line is well insulated from ground. In the text above I was responding to the charging and arcing from a floating antenna, NOT to the mechanism Reg was talking about below. I have NO problem with the wire charging and arcing. But I've NEVER seen a situation where particles directly hitting the antenna make noise, which is what Reg was talking about below.... During the "H Field Antennas" thread, you said the following: ************************************************** ************* Reg Edwards wrote: Precipitation static, eg., from highly charged raindrops and fine snow or fine sand, impinging on the antenna wire, just causes an increase in receiver white noise level. It can be reduced but not removed by using a very thickly insulated antenna wire, like the inner conductor of a coaxial cable complete with its polyethylene jacket. ---- Reg. W8JI replied: I've never seen a case of precitation static occuring that way. In every single case I've seen, whether on tall buildings, tall towers, or antenna hear earth, it has always been corona discharges from the antenna or objects near the antenna. ... 73 Tom ************************************************** ************** I have only noticed the charged particle arcing in Arizona when the wind was blowing and that is what I am reporting. It is not wise to have a large high antenna that was well-insulated from ground, since the accumulated charge can suddenly discharge through a series capacitor and damage equipment. Where does the accumulated charge come from if not from charged particles? If the antenna is link coupled, the charge equalizes between the two dipole elements and, in my experience, doesn't arc. Why do you think it is the particle that make noise or even that they are necessary? Allowing what you say is true, then you are arguing against yourself. As I understand it: 1.) You say the particles make the noise as each individual particle hits the antenna. 2.) You say grounding the antenna eliminates that noise. There is an obvious conflict in those two ideas. Grounding the element for DC will not reduce the rate the rate of energy transfer to the antenna from particle, it can only INCREASE it by preventing long-term charging of the antenna closer to the potential of the particles. 73 Tom |
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