Dave Fulghum's post on renewed activity with non-expendable high-power microwave (HPM) weapons reminded me of an offhand comment at a conference in 2006, where a US officer commented that - in the USAF - HPMs and unmanned combat air vehicles (UCAVs) were so intimately linked that in Air Combat Command, they belonged to the same office.
What might be a big clue emerged in one USAF presentation a few years ago, in the form of a single piece of artwork:
What it shows makes a lot of sense. An HPM is going to work best pointed straight down. since you don't want to defocus the energy by smearing it along the ground. Also, like radar, HPM likes a large antenna (equals narrow beam), and how better to install one - particularly in a small stealthy platform - than horizontally in the weapon bay, aiming down?
Of course, then you need to overfly the target and get as close as possible (effectiveness diminishes with range) and a very stealthy UCAV is a good way to do that. It also avoids any health hazards to an operator, who'd otherwise be sitting a few feet away from a gigawatt-class microwave source.
By the way, someone who appeared very confident in the results of his studies assured me a few weeks ago - quite categorically - that the US already has UCAVs in service, developed and operated in the black world. So maybe that UCAV/HPM office got something done.