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i was told magnetic mounting causes a %30 efficency loss

we're not talking about lots of things here, we're talking about magnet mounts and short shaft open air coil loaded antennas, via booty monsters reference to the 10K. between the two of them the possibility of more waste than 30% exists even if we only consider the percentage in terms of coverage in distance measured in miles. if you want to talk about other things then start a new thread. if not, stick to the topics under discussion.

when you come in here and post crap like this:

"and still no answer about where that "30%" loss thingy comes from. Lots of obfuscation, but no fact, or even a half way reasonable conclusion."

after i have just spent the better part of 7 paragraphs dealing with exactly the issues (and more) that the original poster asked about, the ones that you refer to as "obfuscation" and "no facts and no reasonable conclusion" i can only conclude that you are in the habit of opening your mouth before engaging your brain and you don't read or comprehend the very things you claim i haven't provided. i have nothing to say to you and i don't want you saying anything to me.

i'm attempting to answer his question/s and i'm not interested in talking to you. if it were up to me i would have given you the condensed version of all of this (two words) but then i'm reminded of the responsibility that i have to help maintain a certain level of civility here in this forum and that takes precedence over expediency so i'll use the extra bandwidth instead of telling you what i really think.
 
freecell,
About those 'possibilities' that don't apply to the situation. I figure they have about as much application/probability as that '30%' loss from mag-mounts. That's the only reason I introduces such.
As for the rest of your last post, you might be surprised at how much I comprehend. Be that as it may, you may feel assured that this is the last post from me that you will ever see addressed to you. I certainly can't deny that you have 'good intentions'. I do wonder, at times, just what those 'intentions' are good for. But that's ~my~ problem, isn't it?
- 'Doc

Click*
 
You kids are acting like schoolgirls, and I bet your twice my age.

really, both of you provide a good deal of quality information and many appreciate it, well, at least I do.

So, I just wanted to say thanks to both of you.

And I think the stimulus you provide each other just enhances the disscusions...sometimes.

:D
 
BOOTY MONSTER said:
my vehicle is a montero (suv) . i have a 10k on a magnetic mount on the roof centered over the front passenger area . i was wondering if anyone had went from magnetic mount to a grounded drilled and bolted to metal body mount on a 10k (or any other antenna that you just changed the mount on) and if you could tell any difference . im thinking about remounting it on the roof about a foot from the rear and centered on the roof (not on a rear corner) .will this make it a lil more directional twoards the front of the vehicle or a lot ? i know it will affect it some . ill be using a ball mount with 3 nuts-bolts-washers and a big metal washer with holes for the olts and dual gaskets for water sealing .
thanks
Click to expand...

I don't know about the 30% loss Dude,but i do know i wouldn't run 2 many watts through a 1 mag mount Antenna...but after reading this long story as usual,like i always see..no one quite answers your question..so i will make this simple
if you want to drill a hole in the vehicle ..drill it in the center of the roof..as i say not only will you be styling with looks you also will have a nice rf pattern!!!!

And for the rest of you Great sciencetech guys!!!
some people want simple answers for simple questions!
not a flame up of compare the brain levels and start a issue with each other over the subject..I do see this a lot in this forum..
some useful some just useless!
Wouldn't answering The question first and then debating each other be more of interest to our world...
good example...HOW TO NOT HOOK UP A CB BACKWARDS
and 2 pages of just Pure S$%T over it...Remember man made RED and Black and eyes and common sense!
I mean i like all this great book,hands on tech stuff or whatever you want to call it...but this Won't and will never stop people from doing what they want,if they feel strongly about it..
Remember this is how the stuff was posted in books anyway
Trial and error made this world !!!
 
I was told by a couple knowledgable fellas that there isnt a noticeable difference in performance.

I just moved my 2 meter 5/8 wave antenna from my toolbox to the top of my cab on a single 5" mag. I am getting great performance from it. (of course I did move it higher, but still from a hard mount to a mag mount).
 
And I think the stimulus you provide each other just enhances the disscusions...sometimes.
Click to expand...

C2 I would have to agree with you on this. Though most is over my head, it is a start towards learning.

You know what they say about opposites attract. Then there is that glass that is half full (half empty). Some folks just see things differently. Sure hope both you guys keep those fingers busy. I like to read. With that said good job men.
 
"I just moved my 2 meter 5/8 wave antenna from my toolbox to the top of my cab on a single 5" mag. I am getting great performance from it. (of course I did move it higher, but still from a hard mount to a mag mount)."

and for the reason i mentioned earlier it's not a problem at the higher frequencies.

remember this?

the vehicle is not a ground plane for the lower frequencies, but rather a capacitor to ground, especially when monopole antennas are operating at frequencies low enough that the vehicle body doesn't provide anywhere near 1/4 wavelength of body metal in most or all directions from the antenna mounting location to the boundaries of the vehicle proper. the vehicle body becomes one plate of the capacitor and earth ground the other plate with whatever in between acting as the dielectric.

this is clearly not the case at 2 meters. i don't know too many vehicles that aren't able to provide 20" of body metal in all directions from the antenna at 2 meters. that's as simple as it gets.
 
are'nt most cars about 16 feet long? (not your civics)

Most trucks 18 feet or more?

That seems more than anywhere near enough ground plane.

I'm just thinking of an upright L dipole, which seems to work just fine...kind of looks like a whip on the back pumper, or even on the trunk, to me.

How would you model (block diagram) that theory? I'm picturing a Marconi antenna with a cap between ground. ?
 
Think of it however you want, radials, groundplane, counterpoise, it amounts to the 'other half' of the antenna. A radial for a vertical antenna ought to be about as long as the vertical element until you get to something around 1/4 wave length. After that, it won't hurt to be longer, but it certainly won't help much either. Using a 4 foot antenna? Then the radials ought to be about 4 feet long too.
Having more than one radial means a more symmetrical radiation pattern, instead of the pattern tending to go in the direction of the radial. Something to remember with any HF mobile antenna is that the radiation pattern will never be entirely symmetrical, it'll always tend to favor some direction(s) or another. In most cases that non-symmetrical pattern doesn't make much, if any, difference (if you even notice it). If your vehicle is 20 feet long and 2 feet wide, then I would tend to think that radiation pattern is gonna be a bit more than just slightly directional (at HF). If you drive such a thing would you please post pictures?
A vehicle's body does act as a capacitor to ground ~if~ you're talking about fairly low frequencies, such as below about 20 meters (give or take a bit). That capacitive coupling is very frequency dependent. At 10/11 meters, probably not so much. At 160 or 80 meters, definitely yes. In most cases, also not something you need to worry about much, if at all. As long as the antenna finds a 'ground' close to what it want's to see, good. Who cares how it does it.
- 'Doc
 
its easy drill that hole. yes its much better. do it and never look back.

forget about there reasons and text book crap.
drilling that hole will be the best thing you could do next to good coax and antenna. :)

would you magnecticaly connect a base ? NO
so dont do it on your mobil. PERIOD.
 
BOOTY MONSTER said:
my vehicle is a montero (suv) . i have a 10k on a magnetic mount on the roof centered over the front passenger area . i was wondering if anyone had went from magnetic mount to a grounded drilled and bolted to metal body mount on a 10k (or any other antenna that you just changed the mount on) and if you could tell any difference . im thinking about remounting it on the roof about a foot from the rear and centered on the roof (not on a rear corner) .will this make it a lil more directional twoards the front of the vehicle or a lot ? i know it will affect it some . ill be using a ball mount with 3 nuts-bolts-washers and a big metal washer with holes for the bolts and dual gaskets for water sealing .
thanks
Click to expand...

B M, I wasn`t going to reply but after reading so much BS
I just can`t help myself.

To Answer Your Question Directly, Yes I have tried them all
and I mean them all and NO I can not tell the difference.

If there is a difference, It would take a field strength meter
and a fixed site to measure it.

Since when did 11 meters get to be low frequencies ?

Two meters at VHF and 70 centimeters at UHF don`t make
11 meters a low freq. at least in my mind. Since your antenna
is a CB, aka. export antenna I will asume that this is the area
of discussion.

If indeed all Magmounts are less than ideal I suppose that
everone with Wilson 1000 @ 5000 antennas should S**t Can
them :?

I run a Slingblade on a 4 disk mag mount sitting on a tool box
using a long shaft to keep coil above the roof line.

I have every antenna that Kale has ever made for retail and
some that he dosn`t have on the market and they are
fine antennas.

The Slingblade is a Low Q antenna and as such is not as good
say on the narrow 11 meter band as others, however it is
very broad banded and I can work 24.200 to 27.800 under 1.5
SWR and thats with my toys :)

Damn, to think I lost a couple contest by one contact and
it was because of that stinking Mag Mount that I use: :eek: geezzz

Regards,
John
 
"How would you model (block diagram) that theory? I'm picturing a Marconi antenna with a cap between ground. ?"

...........|
...........|
...........| antenna
...........|
..........__
..........__ loading coil (lossy inductive coupling to body)
...........|
...........X connection to center conductor of feedline -----

...........X shield connection to magnet (plate) ------------
...._________
...........|
...........|
..........__
..........__ capacitance (unknown value)
...........|
...........|
...._________ vehicle body surface (plate)
...........|
...........|
..........__
..........__ capacitance (unknown value)
...........|
...........|
...._________ earth ground (plate)


that includes the magnet mount. two values of capacitance in series. ASCII is a little limited as to what it can be used to display but you get the picture, maybe.
 
freecell said:
"How would you model (block diagram) that theory? I'm picturing a Marconi antenna with a cap between ground. ?"

...........|
...........|
...........| antenna
...........|
..........__
..........__ loading coil (lossy inductive coupling to body)
...........|
...........X connection to center conductor of feedline -----

...........X shield connection to magnet (plate) ------------
...._________
...........|
...........|
..........__
..........__ capacitance (unknown value)
...........|
...........|
...._________ vehicle body surface (plate)
...........|
...........|
..........__
..........__ capacitance (unknown value)
...........|
...........|
...._________ earth ground (plate)


that includes the magnet mount. two values of capacitance in series. ASCII is a little limited as to what it can be used to display but you get the picture, maybe.
Click to expand...

Well as matter of fact I do get it, however I did not present
in theory or state anything as a fact other than my personal
experience..

I do not claim to be a engineer or anyone of higher learning,
but someone able to do deductable reasoning or as I like to
say, make 2 @ 2 come to 4.

When it dosn`t, I know that I am dealing with a problem.

In your diagram we find at least 2 unknowns if I read it right
and if we knew how to fill in those blanks with accurate data
then we might (I said might) get a more complete picture, Yet
since we are in the real world and not in one where antenna theory and other scientific measurements are made using
advanced math ect..
Don`t take me wrong I commend and admire those able to do
so...

With my limited understanding the one I have the most trouble with is that Last Capacitance of unknown value ! and earth
ground, since everything is generally always in motion and of
constant changing earth ground.

Seems to me that would still exist no matter how a antenna
was mounted on said vehicle.

I remain open minded, what little this old dog has left :)

Regards,
John
 

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