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Which Antenna?

todd
Level 1
Level 1

Hi there,

I am trying to determine the best products to improve the strength of a wireless network I manage. This network is located primarily in a 5000 square foot building. I use a 340 series AP and 340/350 series PCI and PCMCIA cards. Performance in this building is pretty good but some spots could be better. This is a two story building with clients on both floors. The AP will need to be on the 2nd floor.

There is also a desktop machine with a 340 series PCI card located in a separate building about 200 FT from the main building. I am able to get somewhat of a signal in this location, enough to use the internet but not enough to maintain a reliable connection to the LAN.

So, I am looking to put new antennas on the AP and the PCI card in the separate building in the hopes of giving the network performance a good boost. I am a little confused about what would be the best parts to use though. I want to use indoor antennas.

At first glance I was thinking that the AIR-ANT3351 would be the best choice for the PCI card in the remote building. But I really only need to boost the signal in one direction, back towards the main building and the access point, so perhaps one of the stronger directional AP antennas(such as the AIR-ANT3549) would work better.

I also want to add an antenna to the AP 340 to increase the general performance in all directions. I am thinking either the AIR-ANT5959 or the AIR-ANT2012 would be most appropriate for this.

Any help would be appreciated.

7 Replies 7

beth-martin
Level 5
Level 5

Your site survey should tell you what you need. First, if you can use the 350’s, they have stronger radios so you’ll get better connectivity. Next, I’m sure you’ll want an access point on each floor and probably one with an external antenna for the remote user. You might get by by upgrading that PCI card to a 350 series and adding a AIR-ANT3351 but without the site survey, it’s just poking and hoping.

sarhoades
Level 1
Level 1

You might want to consider an after-market in-building antenna from Centurion. They offer very low profile antennas for office applications that provide excellent coverage.

They also have a new ceiling tile antenna that completely conceals two 3dBi omni-directional antennas from view. The antennas are actually embedded in a ceiling tile that matches the rest of your ceiling. You can hide the AP and connect via standard coax cable available from Centurion, like CAF94121. Products can be found at centurion.com (in-building) or i-ceilings.com

T

jhelm
Level 1
Level 1

The Armstrong iCeilings panel antennas work very well, we have placed them in buildings both large and small with great results without worrying about the local decor. Good luck and if you need any further assistance then feel free to email for assistance.

ajarina
Level 1
Level 1

I have somewhat the same kind of installation requirement of yours. I did a site survey and there were few points in the building with unreliable connectivity. The site survey was based on an AP with 2dBi antenna. I just wonder if I can use an outdoor antenna like a 12dBi omni Mast mount to be able to have a "bigger" radio cell. Anyone pls reply?

A high gain antenna will definitely provide for a larger cell (I have often used a variety of Cisco, Cushcraft, Wade Wireless and Maxrad omni's to compensate for a "less than optimal signal). The major considerations that apply to the use of alternate antennae in this situation are for the most part A) Is it the fact that the signal strength is too weak to attend to all of the nodes encompassed by your AP cell, or is it the fact that the signal strength to noise level is compromising the connection? If the latter is true then you should first do another (partial) survey for the nodes in question with the high gain antennae for the fact that when you increase the antenna gain you will also stand to potentially increase the signal noise (so if this is your hurdle you will potentially exacerbate the problem and while your cell size will increase you might find that this does not remedy the connectivity problem). B) Where is the AP located (is it in a hallway or a high traffic location)? If the AP is located in an area where the antenna will have to be ceiling mounted a high gain antenna can pose a problem due to their physical size. An 8/10/12 dBi gain omni starts off around 17" and goes up from there so you might find that the compromise to the cosmetic value and the physical intrusion to a high pedestrian traffic area (the high five the protruding antenna syndrome (know this first hand from many campus installs)) might make the use of a high gain omni difficult. A possible suggestion for you (if you need just a little "gain push" to attend to your more remote nodes) would be to try the 5 dBi ceiling mounts that Cisco offers, or try the Cushcraft "Squints" (3.5 dBi). Also, don't forget that while the use of alternate antennae can provide for a larger cell, the "rubber ducks" (2.2 dBi captured or external rptnc connected) provide for diversity which helps to eliminate "dead zones" so you might want to consider the use of two (rptnc) connected omni's.

If you can provide any specifics for your case study or have any other questions please feel free to send me an email.

Robert,

I have quite similar problem but I decided to get more coverage using High gain antenna with a 350AP.

What is not clear to me is if I need to get two AIR-ANT5959 or AIR-ANT2012 for one AP or I can mix (one standard and one high gain) or using just one.

Thanks in advance for your reply.

There is no problem using just one antenna on a 350. Tell the 350 this when you configure it so it doesn't waste time/RF on the unconnected port.

Cisco does not recommend using two antennas with different coverage patterns on a single AP. The receiver will end up sitting on the last antenna used until given a reason to switch, and will miss weak signals only being heard by one antenna.

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