Can anyone tell me how do the glass mount antennas transmit the signal thru the glass?
Glass mount antennas?
- Thread starter N467RX
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n4yek
Member
Well your question can be taken two different ways, 1) how does it and 2) how well does it do?N467RX said:
to answer your question:
1) By capacitive coupling (which is why you can't install it over tinted windows since most tint contains metal of some type)
2) I had good results, tuned up easily and worked real well.
I meant #1, since I'm trying to see if I can do a cheap device just to transmit the signal between the two sides of my window (not willing to pay like $100 to get an antenna down here for 2 months)
n4yek
Member
You can get one for $45 here, dual band:
http://www.mfjenterprises.com/Product.php?productid=MFJ-1734&PHPSESSID=bee082f1f2c9bf171bac0b0a10d3a1bf
or for 2 meter only, just $35...
http://www.mfjenterprises.com/Product.php?productid=MFJ-1738
http://www.mfjenterprises.com/Product.php?productid=MFJ-1734&PHPSESSID=bee082f1f2c9bf171bac0b0a10d3a1bf
or for 2 meter only, just $35...
http://www.mfjenterprises.com/Product.php?productid=MFJ-1738
My problem is that I'm not in the US right now, and I'm only going to be here until August, that's why I'm looking into other solutions.
They have pretty good stuff though, thanks for the link.
They have pretty good stuff though, thanks for the link.
If it's just going to be temporary, Radio Shack sells a glass mount antenna for about $45 as well. And there is no waiting or cost for shipping.
Glass mounts aren't the best, but for close in signals or repeated signals, reception should be adequate. If there are simplex systems you want to monitor, they will be dicey.
Glass mounts aren't the best, but for close in signals or repeated signals, reception should be adequate. If there are simplex systems you want to monitor, they will be dicey.
N1BHH
Member
Any over the glass clip works. I bought a couple from Radio Shack a number of years ago. It has a BNC jack, so you can attach your duck to it, with about 8 feet of RG58/U cable. I will use mine when riding with a friend and don't want to bring a big antenna. Here is one that you could get, similarly constructed: http://www.universal-radio.com/catalog/hamantht/0204.html
n4yek
Member
Glass clips are ok if you don't have tinted windows. You could possibly scratch the tint and have to replace it. Other than that, it is a good temporary set-up.
af5rn
Member
Rather than start a new thread, I would like to take this discussion out a little farther.N467RX said:
Anybody know what is actually inside the coupling box of a glass mount antenna? Is there a tuned load or something in there that is band specific? Or is the whip and external loading coil the only band-specific parts of the entire system?
Could you change a glass-mount antenna's band by simply replacing the whip with a new one cut for a new band, or would the inner workings not match up with the whip? Like, if I am using an Antenna Specialists 800mhz glass mount, can I replace the whip with a UHF/VHF dual band whip and it work just fine on those new bands?
Inquiring minds want to know!
ridgescan
Member
Rob- YOU asking a question?!
JK man-IMO I think the coupler is general delivery which is why the whip and coil (if any) have to be specific.
JK man-IMO I think the coupler is general delivery which is why the whip and coil (if any) have to be specific.af5rn
Member
Well trust me, it has been very tempting to break a few of those things apart just to figure it out for myself, lol! But I figured someone here must have already beat me to it, so no since in destroying a few $70 dollar antennas just to duplicate their efforts!
Anyhow, I'd sure like to think that I could just interchange the whips for various bands!
Anyhow, I'd sure like to think that I could just interchange the whips for various bands!
The last time I cracked one open, it consisted of a round tuneable metal disc that is factor adjusted-variable inductor.
af5rn
Member
Well, I'm a little embarrassed to admit that I am not really sure what that means. In fact, you could have just completely made all that up, and I wouldn't know it. :lol:
Did you mean FACTORY adjusted, or "factor adjusted"?
Are you saying that the coupler is tuneable to determine frequency range or mid-frequency? Or are you saying it is factory tuned and not tuneable by the user? Is the same one in every antenna, or is it a different one in each antenna depending upon the band?
And what band antenna did you break open? Just one or several?
Thanks for the input!
Did you mean FACTORY adjusted, or "factor adjusted"?
Are you saying that the coupler is tuneable to determine frequency range or mid-frequency? Or are you saying it is factory tuned and not tuneable by the user? Is the same one in every antenna, or is it a different one in each antenna depending upon the band?
And what band antenna did you break open? Just one or several?
Thanks for the input!
fmon
Silent Key Jan. 14, 2012
The internal disc is fixed to tune to attached whip. I cut a RS through glass whip to 3 1/4 inch which improves a little on 800 MHz but is deficient on VHF & UHF.
The frequency range is determine by the whip, not the coupler. The coupler merely provides a match to the 50 ohm cable feeding the antenna. I've seen some that are adjustable, which just allows the installer to match for best vswr. Tuning for frequency would occur outside at the whip. If you try to go to a different band, it's likely that the coupler portion would not be adequate to provide a 50 ohm match and, depending on what they're doing, could add quite a bit of attenuation.af5rn said:
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