Bloody 7db mag mount antennas from eBay!

After wandering his feedback(most happy with antenna) i'm guessing alot of people are using 1.2ghz antennas on there gear :/

Well if he says it's 7dbi, you'll have to believe it, unless if you want to get it tested in a laboratory and prove otherwise.

We carry a 7dbi on our catalog as well, which has 2 coils:

HTH / c24

Half an idea of wavelength and antenna theory should do it.. But it looks like that is more rare then first thought.

AdamO hath wroth:

Ummm, I don't think so. I can model the antennas easily enough if I had accurate dimensions. Just looking at both and guessing, I would give the one on the left about 5.0 dB gain. The problem is that the gain peak may not be where you expect. Both antennas are intended to be operated over a ground plane. That will reflect the signal upwards to a considerable degree. You may have 5dB of gain, but it might be at an angle of perhaps 20 degrees or more above horizontal (uptilt). In the horizontal plane, the gain may be considerably less. Fortunately, it's not much of a problem with such low gain antennas because they have side lobes and mysterious gain peaks all over the place.

However, that's not the real problem. It's the coax cable loss. That looks like RG-316 on the right and RG-175 on the left which are both very lossy at roughly 1.5 dB/meter at 2.4Ghz. My guess(tm) is about 3 meters of coax on the left or about 4.5dB loss in the coax. That subtracts from the antenna gain resulting in no net gain. That might be why you claim it was "no good". It's not, but might offer an improvement by virture of an improved location. It's also false advertising for the vendor to not include the coax loss in the specs, but everyone does that so it's difficult to change.

Yes clearly Not and that being my point. Leaving coax out of this as it will only be cut to a very short length and connected to a usb dongle.... At first glance i would be expecting 6db from the right and 4.5 from the left based on antenna theory and practice. The ground plane is a not a worry as usualy a mag mount is on a large metal roof....

The right antenna being for a very different band is the kicker.... More and more people put a nice little spring on the bottom of there

AdamO.

All these dbi numbers and other WiFi antenna talk brings back memories of the glory days of CB. What a waste.

And memories of you Pace 123A?

And memories of your Pace 123A?

Pace 123A! You saying i'm old? :P