whip antenna dissipation ball? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: October 04, 2020, 08:22:18 pm
content: I found a nice whip antenna, and I was looking to see the cost of it, to see if its worth polishing and straitening, turns out it is, with a similar antenna running 55$.However, I noticed the one for sale has something called a static dissipation tip, and I do not have one. Are there any guidelines/design equations for this tip? It sounds like a interesting project to braze one on. The antenna I have is something like 8 feet (I think CB). Supposedly its an antenna feature that lowers wind noise. I see the commercial ones have a teardrop shape.What is the optimal shape? I assume it modified for ease of manufacturing and wind friction reduction.They call it a Coronaball, but I usually associate those with the really spiky ones found on power distribution lines.

author: floobydust
author_rank: Super Contributor
timestamp: October 04, 2020, 09:06:48 pm
content: The RF front-end will have a high value resistor to GND like 1k-33k (10k typ) to prevent charge build up occurring at the antenna.I suspect the small sphere (mass) at the tip makes a pendulum so the antenna swing is not buffeted so fast.Once I drove through ice fog and the tip got ice buildup and the antenna started swinging pretty bad, had to pull over and break it off.

author: coppercone2
author_rank: Super Contributor
timestamp: October 04, 2020, 11:35:05 pm
content: It specifically says it has to do with static, so you think its just preventing motion that results in more static build up? and it has nothing to do with dissipation, just rate of accumulation?

author: floobydust
author_rank: Super Contributor
timestamp: October 05, 2020, 12:46:06 am
content: There's some marketing wank at play too. K40 "no static ball to get knocked off"It's just having no needle sharp point at the tip- which would make a concentrated corona discharge and RF noise. Although a K40 left the tip blunt...Imagine the entire car is generating static charge, so it will prefer to discharge at any sharp point. The sharpest point on a vehicle is the antenna. But realistically the tires dissipate (leak) charge well enough.This is more of a problem for aircraft, they have to check the whole body and sometimes adddischarge wicksbut they have no leakage current path to ground.

author: coppercone2
author_rank: Super Contributor
timestamp: October 05, 2020, 01:10:29 am
content: I have seen really funky ones at a power station

author: Chris Roubis
author_rank: Contributor
timestamp: October 05, 2020, 02:00:37 am
content: Just get one of those ground straps that people used to put on the rear of their cars back in the day.

author: coppercone2
author_rank: Super Contributor
timestamp: October 05, 2020, 04:32:23 am
content: ok, I am really more interested in the technology, its actually interesting, unlike putting an antenna on a car

author: coppercone2
author_rank: Super Contributor
timestamp: October 05, 2020, 04:39:31 am
content: here is one for sale. these people claim it has nothing to do with cars at allhttp://www.antennapartsoutlet.com/Pages/Products/CoronaBalls.html