High Efficiency, Small Volume 44 GHz Transmitter

The replacement of millimeter-wave traveling wave tube by solid-state power amplifiers has been recognized as a very important goal for some time. Solid-state power amplifiers provide the substantial benefits of elimination of high voltage supplies,reduction in size and weight, and generally improved reliability, especially for airborne microwave systems. However, the demand for high power at millimeter-wave frequencies are steadily increasing for today's military and commercial systems such asMILSTAR, SATCOM, GBS and LMDS. The limitation of output power of present MMICs can be partially overcome by combining several of them offers low loss, good amplitude and phase balance, and high power handling capability. Combining approaches can beseparated into two groups: those, which can combine two devices at a time and those that can combine the output of N devices in one step. On one hand, the losses of binary structure degrade the combining efficiency and on the other hand, the n-waycombining structures are designed to combine the output of N-devices in one step. This scheme has the potential of higher combining efficiency. We are proposing the development of SATCOM amplifiers using Gysel Combiner and MILSTAR amplifier using Radialcombiner. The choice is dictated by the availability of the present day MMICs.