Anderton
Karyn
The issue here is wifi drivers, not radio waves and microphones.
I interpreted his original post as talking about a wireless network, e.g., not a wi-fi card inside a laptop or computer but something like a broadband modem from a telephone or cable company, with wireless capabilities. I've had several instances of interference caused by these types of networks, particularly with wireless mics (even digital wireless). I would just turn off the modem to make the problem go away, then turn it back on later when I wanted to watch movies on my iPad 
Yep, My initial though was exactly the same, hence my first reply..
Karyn
What sort of mic? I'm guessing a capacitor... with a screen grounding problem....
RODE NT1A
By pure coincidence I've just finished building a new LDC from a microphone-parts.com kit, so I know all about RF shielding, self noise and interference removal.
Without holding the mic in my hand it's hard to diagnose where RF interference would be coming from. Possible options include, but are not limited to.. Bad screen in the mic cable, bad (loose or dirty) screen connection between interface - cable - mic. Corrosion on the gauze cage around the capsule where it connects to the main body. Corrosion on the main body mounting points. Corrosion at the body split point. Corrosion of the capsule connections to the fet pre-amp. Corrosion on ANY of the solder joints on the pre-amp board. By corrosion, I don't mean anything you can actually see.... but oxidation of the metal surface, creating a partial semiconductor which acts as a diode.
If you can prove it is the mic you have three options.
Fix it
Use a different mic
Turn off your Wifi when you record.