Abstract: A powder bed fusion apparatus includes a build platform movable in a build sleeve, the build platform for supporting a bed of metal powder, a powder layer formation device for forming layers of metal powder to form the bed, a scanner for directing an energy beam to selected regions of each layer to consolidate the metal powder and a radio-wave generator arranged to surround the metal powder and generate radio waves to heat the metal powder that forms the bed.

Abstract: A power amplifier is described that includes a balanced amplifier arrangement having an input quadrant coupler and output quadrant coupler and two amplifiers, which may include or consist of single transistors, there between. The power amplifier also can provide a signal to an isolated port of the output coupler in order to provide impedance matching. This arrangement dispenses with the need for transistor matching networks at the output of the two amplifiers, which in turn enables the power amplifier to be operable over a wider frequency range as compared with a Doherty power amplifier.