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increase ground on mag antenna
- Thread starter Splash1
- Start date
Splash1,
The 'quick-n-dirty' answer is no. The 'quick-n-dirty' solution to that sort of 'problem' is to 'ground' the shield of the coax -at- the point where the magnet is sitting. (Drill hole, feed coax through, ground at that point.) Since that would mean that the antenna wouldn't need the magnet to stay on the vehicle, remove magnet.
Sound like a 'smart-ass' answer? Yes, it is, and sorry 'bout that. But that's because the 'problem' isn't the need for a ground, only 'how' that 'ground' is obtained. There are limits to the use of a mag-mount antenna. (Or a 'through-glass' type antenna too, for that matter.) That limit deals with the area covered by the magnet and the frequency of use.
- 'Doc
The 'quick-n-dirty' answer is no. The 'quick-n-dirty' solution to that sort of 'problem' is to 'ground' the shield of the coax -at- the point where the magnet is sitting. (Drill hole, feed coax through, ground at that point.) Since that would mean that the antenna wouldn't need the magnet to stay on the vehicle, remove magnet.
Sound like a 'smart-ass' answer? Yes, it is, and sorry 'bout that. But that's because the 'problem' isn't the need for a ground, only 'how' that 'ground' is obtained. There are limits to the use of a mag-mount antenna. (Or a 'through-glass' type antenna too, for that matter.) That limit deals with the area covered by the magnet and the frequency of use.
- 'Doc
mags work by capacitive coupling to the bodywork so the larger the area of magnet and the thinner the rubber or plastic boot (dielectric) the better it works,
the first thing i do with my new trimags is throw the stock boots in the bin and fit very thin boots,
i use 3 or 4 x 7" magnets with very thin replacement boots not just because it holds my 10k in place better at speed but because it is measurably better on air than the same antenna on a single magnet in three separate test on three different vehicles and several monitoring stations,
my wilson 5000 works better on the 6" sirio mag than it does on the wilson 5" mag likewise the sirio 3 and 4000hp work better on the sirio 6" mag than they do on the stock sirio 5",
i cannot give you a technical explanation as to why other than increased capacitance so lower reactance to ground through increased surface area and thinner dielectric,
maybe somebody on here can explain it in a technical way,
if i could drill a hole i would imho thats the best way to go but for one reason or another some people cannot drill so we use mags,
placing a thin sheet of conductive material such as aluminum foil flat to the roof under or beside the mag and connecting the shield inside the mag to the sheet with a short strap will increase the coupling to the roof but it wont look pretty and may damage the paint long term,
i have experimented with nickel screening spray and foil like a k40 mag uses on my old mags and they both help coupling to some degree on my magnets
the first thing i do with my new trimags is throw the stock boots in the bin and fit very thin boots,
i use 3 or 4 x 7" magnets with very thin replacement boots not just because it holds my 10k in place better at speed but because it is measurably better on air than the same antenna on a single magnet in three separate test on three different vehicles and several monitoring stations,
my wilson 5000 works better on the 6" sirio mag than it does on the wilson 5" mag likewise the sirio 3 and 4000hp work better on the sirio 6" mag than they do on the stock sirio 5",
i cannot give you a technical explanation as to why other than increased capacitance so lower reactance to ground through increased surface area and thinner dielectric,
maybe somebody on here can explain it in a technical way,
if i could drill a hole i would imho thats the best way to go but for one reason or another some people cannot drill so we use mags,
placing a thin sheet of conductive material such as aluminum foil flat to the roof under or beside the mag and connecting the shield inside the mag to the sheet with a short strap will increase the coupling to the roof but it wont look pretty and may damage the paint long term,
i have experimented with nickel screening spray and foil like a k40 mag uses on my old mags and they both help coupling to some degree on my magnets