Question about Antenna settings on 1852E in Mobility express

[Willem de Groot]

Hi all,

I'm not sure about the settings of the"Antenna Configuration" for an 1852E Mobility Express Access Point.

If I look at the datasheet for the 1852E, it notes that 2.4GHz uses 3 antennas. -> Does that mean that for Radio 1 only 3 Antennas need to be ticked (which 3)?

The antennas I use are AIR-ANT2524DW-R-RF 2.4GHz2 dBi/5 GHz4 dBi DipoleAnt.White,RP-TNC

so, is it correct that I have to change the Antenna Gain for 2.4GHz to 4 x 0.5 dBi?

Thanks a lot

Willem

[pieterh]

>>> Does that mean that for Radio 1 only 3 Antennas need to be ticked <<<

-> NO. the 4th is also used, it means only max. 3 antenna's are used to transmit, this could vary according to client position.

if 4 antenna's are mounted -> all boxes ticked

the current shown  antenna gain settings are correct

   2,4GHz: 2dBi -> 4x0.5dBi

   5GHz: 4dBi -> 8x0.5dBi

[Michael Sales]

pieterh. 

I have 2 x 1562E AP's. One is the RootAP and the other is MeshAP mode to create a bridge. Each uses a single AIR-ANT5114P2M-N external antenna which have 14 dbi gain. Using your info below.

2.4GHz: 2dBi -> 4x0.5dBi

5GHz: 4dBi -> 8x0.5dBi

My setting should be 

5 Ghz: 14dBi -> 28 x 0.5 dBi ?

and according to Cisco's documentation. the antenna is actually 13 dBi gain with cabling.

Would I be right on this?

[pieterh]

No not really,
when I wrote 2,4GHz: 2dBi -> 4x0.5dBi
this meant using 4 internal radio's each at power level 0.5dBi

28 X 0,5 dBi would describe 28 radio-transmitters in above calculation

but i believe the AIR-ANT5114P2M-N only has a single coax-connector?

so you can only attach and use a single radio from the AP and disable the others!

furthermore dB's are not multiplied but added/substracted

-> the 14dBi of the antenna should be ADDED to the dBi's of the radio.to calculate ERP.

or other way around: ERP - Antenna-gain = radio-power

[Michael Sales]

Hi Pieterh,

Okay so that's asking for the radio count. its calculating the Antenna Gain =  (# radios) x 0.5 dBi

Sorry for my ignorance. This is quite a confusing parameter in the WLC as I have looked all over documentation and states very little about how to calculate and that its the radio count. I am only using this as a bridge. they are not taking clients. The AIR-ANT5114P2M-N has two antennas with 2 connector pig tails. Right now, I'm only using the 802.11a side for the backhaul on the bridge.

What should I be using for the radio count? 2?

[pieterh]

The radio count available depends on the electronics circuit in the access point. you do not need to calculate the number?

the 1850 series has a total of 4 connectors each internally connected to a dual-band radio

so 4x 2.4GHz radio's and 4x 5GHz radio's present

as you mention the  AIR-ANT5114P2M-N has internally two antennas with total 2 connectors you can only connect two of those radio's to the antenna.the other two connectors on the AP are unused.

also as the antenna is only 5GHz (not dual-band ) you need to disable 2.4GHz

I also advise to disable the unused 5GHz radios in the AP configuration.

never done this on a 1852, but I guess you do this by disabling diversity and then select the active antenna's