Mag Mount antenna not helping signal or speed at all?

Darkober · EVDO Newbie Joined: 14 Jun 2008 Posts: 9

I bought a mag mount 12" booster antenna for my Alltel UM150. I've been having around 2-3 bars with and without the antenna, and the antenna doesn't seem to change anything with my connection speed.

The booster is plugged in the back of the modem correctly, and the signal will change when I move the booster, but I can't seem to get any difference from the signal I had before.

Help would be highly appreciated.

whyzeman · EVDO Heavy User Joined: 14 Dec 2007 Posts: 104

Most magmounts require a ground plane. I, myself, haven't quite figured out the propery way of creating one (I am told that a car is a ground plane), but that could be your problem.

karlyn · Posted: Fri Jun 27, 2008 1:31 pm Post subject:

whyzeman is correct -- if you don't have the mag mount installed on your car or some other metallic surface you need a ground plane. If you look at the image of the omni antenna you'll see the ring of spikes. These act as the ground plane on this antenna.

Try setting your mag mount on top of a pizza tin or something similar.

Jim_in_VA · Posted: Fri Jun 27, 2008 1:36 pm Post subject:

ground plane specs: http://evdotips.blogspot.com/search?q=antenna+is+crap
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Darkober · EVDO Newbie Joined: 14 Jun 2008 Posts: 9

Thanks for the help guys, but it turns out I ended up putting the antenna outside and coincidentally I stuck in on a metal surface.

But here comes another problem, in that there was no improvement in the reception even after sticking it on some metal. Confused

I'm still running the same as I was.

Gaahhh. Mad

karlyn · Posted: Fri Jun 27, 2008 3:02 pm Post subject:

So what's your RSSI? (In QLM go to Help>About QLM and look for the RSSI for 1xEVDO as shown here near the bottom of the page.) Does your RSSI get better with the antenna (say closer to -75 dBm instead of -85 dBm?

Frankly, it could be you just won't get better throughput because of site congestion, etc.

I don't use an antenna and can't help much more. Is your metal surface the 28" by 28" as recommended in Jim_in_Va's most excellent blog?

Darkober · EVDO Newbie Joined: 14 Jun 2008 Posts: 9

My RSSI for the 1xEVDO stays around 85 dBm no matter whether the mount is plugged in or not.

I have just tried several pieces of magnetic metals, ranging from about 12 inches in diameter to 24, and I had the same results everytime. I also tried mounting it on my car, and I got the same results.

Jim_in_VA · Posted: Fri Jun 27, 2008 3:44 pm Post subject:

Either the antenna or the cable connection is bad. You should see something even if it is a very small gain. Make sure your pigtail adapter is firmly pushed into the UM150, that disconnects the internal antenna and enables the external.
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Darkober · EVDO Newbie Joined: 14 Jun 2008 Posts: 9

I've tried pressing fairly firmly on the adapter, but I'm afraid I'll end up pressing too hard and screwing it up. Is there a point where the adapter will click into place or otherwise?

Jim_in_VA · Posted: Fri Jun 27, 2008 4:35 pm Post subject:

Usually enough so that the smallest part of the barrel connector is not visible. It should be snug enough that it won't fall out if turned upside down. You should feel some small resistance as it couples with the internal connector.
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Darkober · EVDO Newbie Joined: 14 Jun 2008 Posts: 9

Well, it was set up correctly then from what I can see.

Jim_in_VA · Posted: Fri Jun 27, 2008 4:42 pm Post subject:

Then a bum antenna I'd say. Try the coffee can yagi I have on my blog, cheap and very effective.
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whyzeman · EVDO Heavy User Joined: 14 Dec 2007 Posts: 104

Jim, do you have any homemade solutions for those of us with data cards? I don't think I'll really need it though because I went to Lowe's and bought a 12x18 steel plate and mounted it to the side of my house for a magmount and now (according to the new CTR350 firmware), I have 100% signal strength with -51 RSSI but I'm still getting horrid download speeds (400 Kbps with bursts up to 550), but my upload speeds are maxed out (144 Kbps). Little birdies tell me that Alltel is replacing the KPC680's because I've requested that they "reboot" my nearest tower multiple times.

Without the magmount, I was getting 48% signal strength with -88 RSSI.

With the magmount but without a proper ground plane (had it mounted on a bracket equal to the width of the base of the magmount), I was getting 13% signal strength with -110 RSSI. That wasn't even enough to connect with. So, the ground plane made all the difference there.

A test to see about the antenna adapter and if you are connecting it correctly was given to me by one of the admins here: Connect the antenna adapter to the data card without connecting it to the antenna. Your signal should drop to nothing because theoretically, both antennas have been disabled. If it remains the same as if you don't even have an antenna adapter plugged in, then something's wrong.

Jim_in_VA · Posted: Wed Jul 02, 2008 12:49 pm Post subject:

You can fabricate a homemade antenna for an express/pcmcia modem but its a lot more involved. You would make a dipole for the inside of the can and use antenna cable to hook to it via the pigtail adapter attached to the card. However after gathering all the pieces and part it would have been simpler to just buy a directional antenna. However; since you state that your RSSI is -51, that is about as good as you can get and it is meaningless to try and improve upon it. I hope you are not getting that number from the router. If you are that result is woefully misleading.
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whyzeman · EVDO Heavy User Joined: 14 Dec 2007 Posts: 104