A parallel beam is a physical impossibility, especially at those wavelengths.
A phased array does not magically produce a parallel beam. Its main advantage is that the beam can be steered extremely fast, so multiple targets can be tracked concurrently.
As regards hazards to humans, this was done to death in the mobile phone debate. I am not aware of any credible study which found a hazard other than through the heating of tissue, and you need a lot of average power to do that.
A hazard to avionics is more real, especially the relatively flimsy and often badly wired (badly shielded, etc) GA avionics. The data I have on the KFC225 failures suggests that the frequent servo burnouts are caused both by internal and external RF emissions, but the totality of the failures I have had does not map onto published HIRTAs in any apparent way.
Last edited by IO540; 13th August 2011 at 17:52.