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Indoor access points (3702 or 3800 etc.) with Internal or external antennas. Which is better?

Indoor access points with internal antenna or external antenna.Which one is better for indoor installation and why?

1 Accepted Solution

Accepted Solutions

Ric Beeching
Level 7
Level 7

When ceiling mounted, indoor Access Points offer 360 degree coverage (omni directional) which is generally what people want for a data deployment however there are two main reasons why you may wish to use deploy an external antenna:

1) Altering the angle of coverage - For example, you may have a corridor that you mount an AP at on one end and use a semi-directional patch antenna to direct the signal down that corridor. This will enable areas not normally covered by an omni-directional antenna to be covered.

2) Power / SensivityEach AP and antenna both come with their own 'gain' values measured using dB. By using an external antenna, installers can get a higher power (so it will reach further) and/or a higher sensitive so the AP can 'hear' signals better from the clients. This is sometimes a little risky in terms of coverage because you can blast a signal a long way (100-200m) but your client may not have the power to get its signal back, creating a one-directional connection.

Useful antenna guide:

http://www.cisco.com/c/en/us/products/collateral/wireless/aironet-antennas-accessories/product_data_sheet09186a008008883b.html

What I've outlined above is a very general overview of the way some of the antennas and variables work. In reality it requires a bit of testing or site surveying to ensure you get the setup right depending on your requirements, device types and frequency used.

Ric

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View solution in original post

4 Replies 4

Ric Beeching
Level 7
Level 7

When ceiling mounted, indoor Access Points offer 360 degree coverage (omni directional) which is generally what people want for a data deployment however there are two main reasons why you may wish to use deploy an external antenna:

1) Altering the angle of coverage - For example, you may have a corridor that you mount an AP at on one end and use a semi-directional patch antenna to direct the signal down that corridor. This will enable areas not normally covered by an omni-directional antenna to be covered.

2) Power / SensivityEach AP and antenna both come with their own 'gain' values measured using dB. By using an external antenna, installers can get a higher power (so it will reach further) and/or a higher sensitive so the AP can 'hear' signals better from the clients. This is sometimes a little risky in terms of coverage because you can blast a signal a long way (100-200m) but your client may not have the power to get its signal back, creating a one-directional connection.

Useful antenna guide:

http://www.cisco.com/c/en/us/products/collateral/wireless/aironet-antennas-accessories/product_data_sheet09186a008008883b.html

What I've outlined above is a very general overview of the way some of the antennas and variables work. In reality it requires a bit of testing or site surveying to ensure you get the setup right depending on your requirements, device types and frequency used.

Ric

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Hi Ric

Thanks for the reply and documentation provided.

Hi Ric

hope you are good!

Can we mount the dipole antennas as well as directional patch antenna on the single access point?

Regards

Vikas Vashishtha

In theory you could but it might confuse the APs as their radios aren't intended for individual use rather they work in tandem to get the best possible use out of them. It is very likely you would just introduce more issues by going with multiple antenna types on the same AP.


Ta,

Ric

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