Do magnet mount antennas need some kind of capacitor to make up for the lack of a ground or does the magnetic field do that?I see magnet mounts for sale that just have the coax shield soldered to the magnet holder.
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Magnetic antennas
- Thread starter sportygreg
- Start date
The Wilson 1000 (or was it the K-40) has two thin layers of metal film on each side of the magnet. The magnetic field helps simulate an actual ground connection to the vehicle body.
Not all antennas are set up this way however.
Not all antennas are set up this way however.
Or to paraphrase what 'M.C.' said, no they don't. Some particular manufacturors do use a capacitor in their mag-mounts, some don't. If it doesn't specifically say to add one (and why didn't 'they' add it?), then it isn't needed. The magnetic field doesn't do anything except hold the thing to metal, doesn't contribute to any 'capacitive' affect. A same sized chunk of iron/steel/whatever would 'do' instead of the magnet, just wouldn't hold the antenna on too securely (just acts as one 'plate' of the capacitor, you know?).
- 'Doc
- 'Doc
The reason I asked is I bought a cheap mag mount center loaded antenna for the wife's car and I could not tune it to less than 2.5:1 SWR. You get what you pay for-I just ordered a Little Wil instead.The wife doesn't want a big antenna or any holes drilled in her car!
sportygreg,
The first two things that come to mind are that the antenna wasn't 'tuned' correctly, or the thing just wasn't any good. (Does NOT mean I think you had to have tuned it wrong.)
Very short antennas are sort of like 'experts'. 'Experts' know more and more, about less and less, till they know everything about nothing. (I am an 'expert', by the way.) So, very short antennas tend to be VERY difficult to tune because they usually are only 'match-able' on very small selections of frequencies. Small enough that you can pass the 'matched' frequency and only see a 'twitch' of the SWR needle, easy to miss.
Then again, you might have bought a piece of junk. I don't have the slightest idea.
Ain't all this stuff fun?
- 'Doc
The first two things that come to mind are that the antenna wasn't 'tuned' correctly, or the thing just wasn't any good. (Does NOT mean I think you had to have tuned it wrong.)
Very short antennas are sort of like 'experts'. 'Experts' know more and more, about less and less, till they know everything about nothing. (I am an 'expert', by the way.) So, very short antennas tend to be VERY difficult to tune because they usually are only 'match-able' on very small selections of frequencies. Small enough that you can pass the 'matched' frequency and only see a 'twitch' of the SWR needle, easy to miss.
Then again, you might have bought a piece of junk. I don't have the slightest idea.
Ain't all this stuff fun?
- 'Doc
It was a piece of junk from the Antenna Farm-when I complained about it the guy from the Antenna Farm said "It is my understanding that anything below 3:1 SWR is acceptable and suits the needs of most people"! This moron is in the business of selling radios and antennas and actually told me that! Then he said most antennas are "factory tuned" and don't need adjustment! I replied that I was throwing his junk in the garbage and getting a real antenna and that's the last I heard from him.I am keeping the magnet so I can beat myself in the head with it for being so stupid! 
no....Denton, Texas is the location of the FEMA Region 6 Communications & Data Center, "The Antenna Farm" is located in Sherman, Texas.