Directional/Patch Antennas

[paul_erion]

I'm wondering how directional a patch antenna is ... for example, if I mount a directional/patch antenna (for a 1252) in the middle (horizontally) of a 60' wall, will there be signal at the endpoints of the wall?

Thanks,

Paul

[Leo Laohoo]

Hi Paul,

Have you tried Cisco Aironet Antennas and Accessories Reference Guide (http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/product_data_sheet09186a008008883b.html) or the Cisco Aironet 2.4 GHz and 5 GHz Antennas and Accessories (http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/product_data_sheet09186a008022b11b.html)?

Hope this helps.

[paul_erion]

Thanks for the reply ... yes, I did look at those, and they were helpful. Unfortunately, I'm not quite sure how to read all of an antenna's specs (i.e., how to translate them into the specifics of my question). In particular, I'm not sure how to interpret the radiation pattern graphs, and how I can apply them to the specifics of a building/structure.

[Scott Fella]

There are alot of site out there with the information you are looking for. Take a look at this:

http://www.astronwireless.com/topic-archives-antenna-radiation-patterns.asp

[paul_erion]

Thanks for the pointer!

So if I've understood what's going on (which is not a safe bet), by looking at the "Antenna A Elevation and Azimuth Pattern" for the AIR-ANT2430V-R antenna (http://www.cisco.com/en/U/docs/wireless/antenna/installation/guide/ant2430v.html) I could figure that the antenna shows a loss in the elevation plane of approximately 7 dBi at 120 degrees at 30 meters. Am I close?

Thanks,

Paul

[Scott Fella]

That is correct. The low points between a wave is considered null and is your weakest signal. Again, this antenna is an omni directional, so depending on your environment, it can change. Distance also varies depending on your environment and what db you require.

[scottmac]

If the patch antenna says it covers 180 degrees, then the wall's end wold be covered.

The diagrams are showing you what the pattern looks like from the top, and what the pattern looks like from the side.

Think of what a doughnut looks like from the top (a large circle) and what it looks like from the side (a smaller circle).

The limits of the diagram are usually 6db, corresponding to ~25% of the original radiated power.

Good Luck

Scott