One of many start-ups focused on antenna technologies for squeezing more capacity out of existing spectrum and footprint, Blue Danube Systems is poised to start trials of its BeamCraft 500 offering. AT&T is hotly tipped to be an initial triallist, since it is also an investor in the Silicon Valley company, along with Sequoia Capital, though Blue Danube says it has agreements with multiple mobile operators and OEMs. It says its antenna technology can boost capacity as much as tenfold without new towers, and at far lower cost than many of the beamforming innovators which have come before, such as ArrayComm. The product, currently targeted at LTE networks in the 1.7 GHz to 2.3 GHz range (AWS and PCS in…