Aironet external antenna configuration question

[joey.debra]

Hi,

I've been looking and looking for an answer but I just can't seem to find it.

In Aironet AP's with external antennas like the 1562E which I have to survey with have the option to use 2 dual band antennas on the bottom of the AP or use single band antennas 2.4 GHz on the bottom (1,2) and 5 GHz on top (3,4).

But configuration wise I just can't grasp the whole A, A+B, A+B+C, A+B+C+D thing.

In the current configuration for my survey I'm using two dual band ANT-2547VG Omni antennas on the bottom of the AP so I have configured the antennas to be dual band and set both 5 GHz and 2.4 GHz to A+B which I assume to be correct.  The aircheck showed a similar RSSI from where I was standing after I made the configuration.

However being mobility express for the survey I did encounter a bug where I couldn't set the antennas to dual band in the gui and everytime I change an antenna setting it reverts to the following config: single band, 5 GHz A, 2.4 GHz A+B.  Then the 5 GHz signal disappears or becomes really weak (-69 dBm next to the AP).  I could only manage to get my desired config by putting first both 2.4 and  5 GHz to A+B and then putting everything on dual band using CLI (config ap antenna-mode dual SurveyAP).

So for now I'm safe to conduct my survey 
Tx powers are also set to fixed values 13 dBm on 2.4 GHz and 16 dBm on 5 GHz.

But how do you configure if you have 2 sets of 2 single band antennas for the top and bottom?
You can't set 5 GHz to C+D because it starts at A.  So what's a valid configuration here?

And when do you use the A+B+C and A+B+C+D configs?
Does this also affect the whole XOR radio thing?

For both my questions the cisco documentation seems to be lacking big time.

Thanks in advance!

[pieterh]

I doubt if I understand your question about A+B+C+D?

and i don't think the 1562 has XOR radio?

there are AP's with single, dual, triple and quad antenna connectors (radio's)

the 1562 only has 2 (or 2 times 2)  so this is only A+B if you use 2 antenna (per band) for diversity

or you can use A or B separately if you use single antenna and do not use diversity

NB! in single band it is A+B (1/2 ) for one band and also A+B (but 3/4) for the other .

there are other model AP's that use 3 or 4 (dual-band) radios so there you can use antenna's A+B+C (+D)

does this help?

[joey.debra]

So this is the configuration I mean.
Configuration in MOBEXP

And indeed the 1562E is a 2x2:2 AP.
So if I read your response correctly and logically deduct.
When you have 2x2 radios you can only choose A and A+B.

So in this case the AP has ports 1 and 2 on the bottom (dual band or 2.4 GHz) and 3, 4 on top 5 GHz only.
If single band would have been selected and A only for 5 GHz, only antenna 3 would be used for 5 GHz or A+B then antenna 3, 4 would be used.

Same for 2.4 GHz but A = Antenna 1, and A+B = Antenna 1, 2

So if you'd have a 4x4 AP like a 2802E you'd need 4 dual band antennas and select A+B+C+D for both 2.4 and 5 GHz and choose dual band.  Correct?

My other question about the XOR was a general question how this configuration would affect AP's that support it also like the 2802E.

Thanks for the first response!

[pieterh · Accepted solution]

Yes, you (almost) got it.

normal with single band and diversity on you chose A (one antenna) or A+B (two antenna)

you got the physical connections right, and yes the 2802 uses A+B+C+D.

if you switch off diversity then you could also choose B as single antenna.

but this will be used only in very special setups.