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Old 11-12-2013, 10:51 AM   #1
donnie
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Default New MH antenna Question

Hopefully, we will be taking delievery of a 2013 Forest River Berkshire 36' pusher soon.
My question is, being it's a new rig snd I don't want to drill holes, I'd like to use a thru the glass dual band antenna on the drivers side window.
At the very top of the window there is what looks like a "mesh".
If I put the antenna just below the mesh, would it be ok?
Thanks.

73
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Old 11-12-2013, 03:02 PM   #2
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Congrats on the shiny new rig! Soon enough, you'll be poking holes in it anyway, but only after it gets to where it needs washing.

A through-the-glass antenna ought to work well, as long as there's no conductive coating on the glass -- which is probably the case, because they wouldn't likely use the mesh and a conductive coating.

The mesh itself may be conductive, and might interact with the antenna to detune it if it's right next to the glass-with-mesh. In that case, lean the antenna away from the mesh about 30 to 45 degrees. This will affect transmitted and received signals surprisingly little. The cosine of 30 degrees is about 0.866, a negligible loss of 0.62 dB. Even at 45 degrees, cos 45 degrees = 0.707, a loss of 1.5 dB, which is 1/4 of an S-unit, so it's negligible. At 60 degrees it gets noticeable, 3 dB or half an S-unit.

If the mesh is conductive, it may reduce your signal toward starboard, just by being in the way. Forward or aft, no. To port, it may even increase it.

I've had good luck with through-the-glass antennas on the windshields of classic Thunderbirds and also on Corvettes, back when I could afford neat cars. Let us know your results.

LATER -- Oops, I allowed an interesting technical error to creep into the discussion above. Tilting the antenna reduces the signal (both ways) because it misaligns the receive and transmit antennas, no matter which is which. It reduces the voltage induced in the receive antenna by the cosine of the angle of misalignment. But since nothing you do to the transmit antenna changes the impedance of the receive antenna, the current in the receive antenna changes by the same ratio. Thus the power in the receive antenna is reduced by the square of the cosine. So at each angle the loss from tilt, in dB, is exactly twice what I stated above. At 30 degrees it's about 1.24 dB, at 45 degrees it's 3 dB, at 60 degrees it's 6 dB. This still shows that tilting the antenna doesn't hurt much; at 60 degrees it's still only 1 S-unit.
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Old 11-12-2013, 07:18 PM   #3
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The mesh is likely just a sunscreen. Call the manufacturer to see what the screen is made of. It's likely plastic, part of the safety glass anti-shatter material. If it is, then it has no effect on the antenna, as there is plastic in every automotive windshield and these antennas have worked fine for years through them.

Nothing beats the excitement of waiting for a new rig to arrive!!
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Old 11-30-2013, 02:04 PM   #4
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Congrats on the shiny new rig. Your thru glass antenna will NOT work on your drivers side window simply because it's a dual pane window. If it's single pane, someone goofed in the manufacture and assembly process. I removed the outer pane on one of my rigs and it worked great. Removed as in broke it into enough small pieces to get it out.
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Old 11-30-2013, 07:25 PM   #5
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Doc, are all new MHs glazed with double panes these days? I wish mine were. My windows might as well be glazed with diamond (best heat-conductor there is) or silver (second-best), for all the good they do as insulation.

But of course you're right, if his are double-paned the through-glass antenna won't work. Oh, well, he can put it high on the windshield.
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Old 12-01-2013, 06:25 AM   #6
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Carl, As far as I know, all the mfg now use double pane safety glass on their windows. On my previous rig, I tried the windshield, but the glass had a coating on it and it was too thick to work. Many small taps with a ball peen hammer finally broke the outer side glass and all was well.
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Old 12-08-2013, 07:29 PM   #7
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You don't need to drill holes. I bought 2 ladder mount antenna brackets $35 each. I mounted hf ant to one and vhf ant to the other. Ran coax down the ladder and under coach to the front. I set the rig between the seats in front. Works for me. I run an Icom-706 and LDG auto tuner. I'm getting good reports on a ham stick. I did have to ground my ladder with aluminum strap and stainless hose clamps.
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