Hi Terry,
Each Antenna has a specific use/pattern. If you are adding the 5Ghz modules (A-Radio) then you will want to use an Antenna that supports 5Ghz like the one listed below;
This is the one you listed, which is for b/g 2.4 Ghz;
Cisco Aironet 2.4 Ghz Articulated Dipole Antenna (AIR-ANT4941)
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This document outlines the specifications and description of the 2.2-dBi articulating dipole antenna. This antenna operates in the 2.4- 2.5-GHz band and is designed for use with Cisco Aironet radio products utilizing a reverse-polarity threaded naval connector (RP-TNC).
https://www.cisco.com/en/US/docs/wireless/antenna/installation/guide/4941.html
This one supports 5Ghz;
AIR-ANT5135D-R Omnidirectional
Indoor-only black dipole like omnidirectional antenna for 5 GHz. Used with the 802.11a radio (AIR-RM22A) and the 1200 Series access point.
http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/product_data_sheet09186a008008883b.html
Cisco Aironet 3.5-dBi Articulated Dipole Antenna (AIR-ANT5135D-R)
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This document outlines the specifications and describes the Cisco Aironet 3.5-dBi Articulated Dipole Antenna. The antenna operates in the 5-GHz frequency band and is designed for use with Cisco Aironet 5-GHz radio products using a reverse-polarity Neil Councilman connector (RP-TNC).
http://www.cisco.com/en/US/docs/wireless/antenna/installation/guide/ant5135d.html
The chances are pretty good that you don't require 2 of the Ant4941's or 2 or the ANT5135D-R's attached to each AP unless you require "Diversity" mode to overcome Multipath issues.
Hope this helps!
Rob
