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802.11b and leaky coax antennas

Does anybody have information or experience integrating leaky coax with aironet 1200 aps?

2 REPLIES
Anonymous
N/A

Re: 802.11b and leaky coax antennas

Leaky coaxial cable and other types of radiating antenna distribution systems can work successfully in places such as miningshafts, tunnels and manufacturing areas with severe multi-pathing.

I know of customers who have successfully deployed these types of systems for several years now, but there are some concerns that arise with using this type of antenna technology.

A few issues that arise concerning leaky coaxial cable is that the radiation pattern can change with each type of deployment and the grade or quality of leaky coaxial utilized. Some types of cables favor

radiating at the "ends" of the cable while others will change the radiation pattern depending upon length of cable used and the bends and twists that occur after it has been installed.

Other issues that can also arise such as loss of antenna diversity, contention with other Access Points co-located on the same cable, radiation pattern and performance have not been characterized, antenna is not easily moved nor can that system be easily reproduced to diagnose problems with the antenna system.

There is also an issue regarding certification if it is deployed in the United States. When certifying FCC Part 15 devices, typically the entire

device (Access Point, Bridge, cable, antenna) are typically certified as a whole component and then an FCC grant number is assigned to that product.

Since Cisco has not certified leaky coaxial cable systems as an approved antenna, once you deviate from Cisco approved antennas the onus of compliance falls directly on the installer and/or operator of the device hence the following disclaimer as found on the Cisco AP-1200

documentation may apply.

------------------------------------------------------------------------

------------------------------

Caution: The Part 15 radio device operates on a non-interference basis

with other devices operating at this frequency when using integrated

antennas or those listed in Table B-1. Any changes or modification to

the product not expressly approved by Cisco could void the user's

authority to operate this device.

------------------------------------------------------------------------

------------------------------

Although one might examine FCC Part 15 rules and regulations and interpret that leaky coaxial cable could be installed provided it was done by a professional installer, there are portions of the FCC rules and regulations that seem to indicate certification would be required. Certification involves submitting the Access Point and antenna together and acquiring an FCC identification certification number. To date, I am

only aware of one company URL http://WWW.mobileaccess.com that has submitted Cisco's product along with their antenna solution for FCC certification.

Again, when using leaky coaxial cable antenna distribution systems, it is strongly suggested that the installer and/or operator seek certification and/or determine that their system is operating in

accordance to FCC rules and regulations as the onus of compliance (when deviating from Cisco approved antenna products) falls directly on the installer and or operator.

Cisco offers a diverse selection of Cisco approved antennas that can accommodate almost any type of installation or need. Cisco did not certify or add leaky coaxial cable to our line because of the changing properties of leaky coaxial cable and the difficulty typically encountered with installing such a system.

You should refer to FCC part 15 rules and regulations which can be found at this URL

http://www.fcc.gov/oet/info/rules/ specifically FCC 15.31d and this paper (see page 5 where it clearly states Leaky coaxial cable systems require certification).

http://ftp.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oe

t63/oet63rev.pdf

Green

Re: 802.11b and leaky coax antennas

For non-Cisco-approved, or unusual setups or configurations, check out Andrew Corp (www.andrew.com). They offer custom design / implementation services, leaky coax (their brand is "Radiax").

The have a variety of signal distribution systems, cabling / non-cabling options, amplifiers, and other components.

They also have the engineering, expertise, and equipment to verify and certify compliance with whatever local codes, rules, and regulations are in-place for the location.

"If you just can't do it Cisco's way, give Andrew a shot" They're good folks, very sharp (not cheap, but they're worth every cent, IMHO).

Good Luck

Scott

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