# Metal plate for antenna...



## jmdaniel (Apr 29, 2007)

Does anyone know if using the metal plate to mount the magnetic antenna increases the reception, or if it is simply something to give the magnetic base something to "stick" to?


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## harsh (Jun 15, 2003)

jmdaniel said:


> Does anyone know if using the metal plate to mount the magnetic antenna increases the reception, or if it is simply something to give the magnetic base something to "stick" to?


Just something to stick to. Many of the newer cars are using non-ferrous body parts. Large ground planes don't apply at these wavelengths.


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## Lee L (Aug 15, 2002)

I'm not an EE or anything so I can't say anything on my own, but XM consistently said that installing the antanna on a metal surface would improve reception. Their antennas came with magnet back as well as adhesive sicky pads, but they always said to install on metal.


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## jmdaniel (Apr 29, 2007)

All right, that's one for, and one against. I also have a note in to XM, so we'll see what they say. 

The reason I ask is that I got a SkyDock for Christmas, and am mounting the antenna in my FJ Cruiser. There is a nice spot in the cowl of the vehicle, (windshield wiper area), that is accessible by pulling one of the vent covers, and placing the antenna inside. The metal area inside this space is a bit down, and I had some dropouts when I had it placed there. There is a better spot, up higher, but the antenna then sits, (duct taped), on a plastic piece. Less dropouts, but some. If the metal plate helps, I will add one, and stick the antenna on that. If it doesn't, I'll be forced to pull the antenna out of this area, and mount it somewhere where it is visible. I'd rather not do that, if I don't have to.


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## Hardin Thicke (Jun 18, 2008)

I believe the correct answer would be, "It depends". There are some new antenna designs out that do not need a ground plane. But the vast majority of the run of the mill magnetic mount antennas (pucks, etc.) will benefit from a good ground plane. The metal vehicle body is the other half of the antenna. While it's true that the area need not be as large as what's required for the FM broadcast band, any area you can get under the antenna is better than none at all. Like all mag mount antennas, the ground plane is capacitively coupled to the antenna itself.


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