TECHNICAL FEATUREMICROWAVE JOURNAL EDITORIAL BO AR D REVIEWED

tions. A single-chip amplifier capable of pro-ducing in excess of ten watts at Ka-band or Q-band, or several watts at V-band or W-band, represents an enabling technology in many cases. A new approach to millimeter-wave ampli-fication called the grid amplifier, developed at the California Institute of Technology,3 ad-dresses the need for higher power solid-state amplification. The grid amplifier uses a tech-nique known as spatial power combining, in which the outputs of many individual ele-ments are combined into a beam in free space, circumventing the losses associated with conventional power combining schemes. Previously, spatial power combining has been demonstrated as a method for producing mil-limeter-wave output powers well in excess of 10 W.4,5 However, the earlier implementations of spatial power combining used multiple chips and involved substantial hand assembly and tuning. The grid amplifier spatially com-bines the outputs of a large number of transis-tors fabricated on a single chip, resulting in