I've acquired a pair of single chain panel antenna (12"X12") with a RB133c and R52n (350mW). Since there was no password set, I could see that they were configured for 5GHz. However, there is no markings on the antenna so I have no idea of brand or gain. I would guess 18-21dbi. I would prefer to use these as a PtP bridge in 2.4GHz due to trees. I would like to make a link that is approximately 1/4 mile but has some trees. Does anyone have any guess on how the antenna designed for 5GHz would perform in 2.4GHz?

It would performe poor.

Actualy there is some combi antennas. But still not as good as pure 2,4 and or 5ghz antennas.

5 GHz antennas are made for the 5 GHz frequency also 2.4GHZ antennes are made for 2.4GHz wifi radios
Use of a 5 GHz antenna on a 2.4 GHz Wi-Fi radio the standing wave ratio will be too high and destroy the wifi radio

5 GHz antennas are made for the 5 GHz frequency also 2.4GHZ antennes are made for 2.4GHz wifi radios
Use of a 5 GHz antenna on a 2.4 GHz Wi-Fi radio the standing wave ratio will be too high and destroy the wifi radio

Really? Does it means 5GHz antenna used on 2.4 GHz Wi-Fi radio will damage the hardware radio chip?
Another problem is how about 2.4G antenna used on 5GHz Wi-Fi radio?

Indeed, the hardware is going to break.
The end-transistor shall burn out
Each antenna is built to function in its own frequency
All has to do with the SWR (stand wave ratio)
http://en.wikipedia.org/wiki/Standing_wave_ratio

Indeed, the hardware is going to break.
The end-transistor shall burn out
Each antenna is built to function in its own frequency
All has to do with the SWR (stand wave ratio)
http://en.wikipedia.org/wiki/Standing_wave_ratio

Thanks for your reply, but it's very complicated. I just want to know how about 2.4G antenna used on 5GHz Wi-Fi radio? can this damage the Wi-Fi radio chip too?

Yes Tournet, this shall distroy the radio card.

tournet As for the performance of these antennas, think like this, small car and a pickup truck, take a tire from one on try to install on the other.

Will it fir or work? Maybe, will it work correctly? NO. Will it cause damage? YES.

Radio equipment is designed to work CORRECTLY with the matched antennas and cable.

DO IT RIGHT OR NOT AT ALL.

You re are right

Try to use a 5 ghz antenna and a old XR2 card. Its destoied in less than 6 hours. It will even break/burn, if used for some weeks without lients connecting to antenna.

Indeed, the hardware is going to break.
The end-transistor shall burn out
Each antenna is built to function in its own frequency
All has to do with the SWR (stand wave ratio)
http://en.wikipedia.org/wiki/Standing_wave_ratio

I have only seen SWR meters up to 2.4Ghz but not 5GHz?
So without a meter, SWR cannot be measured,
Also do all antenna manufacturers use full wavelength or is half or quarter wavelengths used.