I have bought and set up a Ubiquiti NanoStation M2.
Now I am planning to place it on my chimney mast (5 to 10 feet above the chimney) either below or above the ground plane for a 2 meter ringo.
Because I want the NanoStation as high as possible, I wonder if the NanoStation interfere with the 2 meter antenna and/or vice versa, if I place the router between the ringo ARX2B and its ground plain (which is about 2 meters below)?
The only time I've seen issues is with a 2Ghz node near (within 2 feet) of a high power 900Mhz transmitter.
I have a node directly under the ground plane of a 2m antenna on my tower with no issues.
Agree, not a problem.

Here's a rocket on an omni and a nanobridge on 5GHz on a rooftop with commercial and other ham transmitters.
Recently set up a NanoStation M2 below a commercial spec portable repeater (x2 Motorola GM300's battery powered into duplexor with RG213 . The cables for both radio systems were placed opposite each other on the short telescopic mast on our comms trailer. When a site test was done it was noticed that the hand portables on the repeater could no longer be heard although on a previous visit to the site the radios worked fine.
The repeater was moved to another location and then worked faultlessly. The NanoStation M2 appeared to work all the time (it hadn't been modified to mesh at that time).
There was no time to investigate why the repeater was not receiving properly but the Ethernet cable to the Nano w2as a cheap cable. If I get time I might be able to simulate the conditions again.
I forgot to mention only the repeater installation was moved the NonoStation was left in the same place.
I posted a spectrogram previously showing the broadband "hash" and miscellaneous carriers that a typical plastic box Ubiquiti device radiates. In a strong-signal environment this is not likely to be a problem. But any ham doing (relatively) weak-signal work should not expect that they can mount one of these devices right on top of their existing antenna installation without some adverse effects on reception. The Rocket device can be put in a shield box - the nano station is much harder to shield. If the signal is emitted from the Ethernet cable, then ferrite cores might help. But if the nano-station is close enough, direct radiation through the box will be the limiting factor.
http://www.aredn.org/content/rocket-shields
I would recommend using shielded CAT5E cable when around 2m equipment. I know I have seen the RFI from Ethernet cable cause interference on the 2m band. How much interference depends on which 2m frequency you are trying to receive on, but it just seems like good engineering practice. Ubiqiuity recommends it (demands?) in some of their documentation. Depending on where you live, you may not have much luck acquiring shielded CAT5E locally, but it is easy enough to come by online. A bit more of a pain to install the connectors than for unshielded, but certainly manageable. I can't speak to RFI to other bands since I spend most of my time on 2m. I have heard elsewhere that the Ubiquity PoE power supplies generate RFI on lower frequencies, but I haven't explored that myself.
Dave
Dave