Definitely not just an LRAD, if it was LRAD at all. It had to an Active Denial Weapon using microwaves. The fact that this could be measured says it was being misused and possibly a military version of the weapon. Civilian devices would be expected to pulse rapidly to avoid overexposure.
An operational version of the Active Denial System (2008), as demonstrated to the US Army brass.
This is the video from the article. It takes a minute to load.
File:Active Denial System Demo.ogv
At seven football fields away, a person wouldn't know where to run to get away so the burn could continue.
All of those who don't believe it exists...