J9000A antenna (with a 530na AP)

[Martin Dettbarn]

So is it just me, or does it seem odd for an indoor/outdoor directional antenna to only come with 2' of cable?

That would be great if I wanted to mount the 530 in a wiring closet or on my desk, but you'd think for the cost of the antenna a little more cable length would have been included.

Does anyone know what a max length is for this cable (whatever it is)when connecting to a 530?

Thanks.

[Matt Hobbs · Accepted solution]

There is some good information on cabling recommendations for these antennas here: http://www.hp.com/rnd/pdfs/antenna_tech_brief.pdf

If you need a long distance between the AP and the antenna, you should get LMR400 type cabling.

[Rich S]

Because of the frequency there can be a lot of loss of signal in a long cable. You must use a heavier cable for longer runs.

http://www.radiolabs.com/products/cables/cable.php

http://www.shop.com/op/aprod-p49941882-k24-g1-~wifi+low+loss+cable-nover


http://search.ebay.com/wifi-extension-cable_W0QQfkrZ1QQfnuZ1


Rich


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[Karsten Breivik_1]

The operative word here is attenuation. This is loss over the length of the cable. The longer the cable, the poorer quality cable and the higher the frequency, the more attenuation you get. At 2.4 GHz frequency on which 802.11b/g operates on the attenuation in the cable will get very pronounced.

You can use a longer cable, just make sure you get the right cable. You want a 50 ohm cable of high quality. Get AIRCOM plus or AIRCELL 7 cable. These have loss of about 0.2-0.4 dB/m. Also, add about 1 dB loss (I think - comments, anyone...) for each connector. If you have an external directional antenna with a 6 dB gain the math for how long your cable should be will be pretty simple. Generally I guess I would be careful with cables much longer than a couple of meters.

Your local radio shop and actually some computer stores I have seen may try to sell you standard RG-58 50 ohm cable which is used for radio amateurs operating in the 27 MHz band or for old thinnet ethernet. If you use this, you might be cheaper and just as well off using shoelaces for cable.

See http://www.on1hh.be/ham/coax/ for a comparison of loss in cables.