Aruba Support answer!!!
The setup which have deployed is not going to work well because both antennas are physically connected to one radio chain on one radio chip.
This chip has no method to use either of the 2 physical pieces of metal for RX or TX, everything heard on both or either antennas, is delivered to the chip, and treated as RX.
Also everything sent from the chip will radiate from both antennas, depending on the quality of the splitter, almost equally.
Also you need to be on ANT-0, not ANT-1, on the 2.4Ghz antenna. If you are on AOS 6.3, you can also re-provision the AP to just use a single-antenna which will disable diversity.
To be safe, a 50-Ohm cap should be placed on the unloaded antenna connector.
However, note that running your antenna in to a splitter and then connecting an antenna on each side of the splitter to be in two different rooms will result in very poor performance. Since the antennas are in two
different rooms, there's no way to mitigate client collisions and hidden node issues from the clients in the two different rooms.
1. You can provision your AP onto a specific antenna via 'Configuration > AP Installation'
2. If you would put a cap on the ANT1 port just to be safe and make sure that the unused antenna is loaded with 'something'. It can't hurt and can only help make sure it works correctly and protects the radio should it be mis-configured later (it also makes it physically/visually obvious how it is configured).
3. Configure an AP-specific RADIO profile to disable CSD
4. Configure your HT profile on the SSID profiles assigned on those APs to MCS0-7 only .
Again, because you are splitting the RF into two different antennas covering two different areas, you will very likely see performance issues (your previous map didn't make clear to me what you were trying to show, but your drawings with the splitter show two separate antennas in two separate rooms, which will not work well).
As far as the steps, you're doing what you need to do, short of visually confirming that you have provisioned the radios and that the antennas are indeed connected to the correct antenna port (which I assume has already been done).
No not every single step above is required, if you are provisioning on to a single antenna, per your screenshot, and have CSD override enabled, that should be all you need to do. But we recommend terminators and static MCS rate limiting.
It sounds like we need an AP in each room, and there is no method to dictate exactly which antenna is used for RX or TX.
We would not consider this valid, as it's likely to not provide good service..