High Efficiency, Small Volume 44 GHz Transmitters

The replacement of millimeter-wave traveling wave tube by solid-state power amplifiers has been recognised 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. Hoever, the demans of higher power at higher frequencies are stedily increasing in today's molitary and commercial applications such as MILSTAR,SATCOM, GBS and LMDS. The limitation of output power capability of state of art solid state devices can be partially overcome by combining several devices or amplifiers. A difficult aspect of designing a combiner is finding a scheme that offers low loss,good amplitude and phase balance, and high power handling capability.Combining approaches cccan be seperated into two groups: those which combine two devices at a time(binary) and those that combine the output of N devices in one step(n-way combiners).Onone hand, the losses of binary structures degrade the combining efficiency and on the other hand, the n-way combining structures are designed to combine the output of N devices in one step. This scheme has the potential for a higher combining efficiency.Wepropose the development of MILSTAR SSPA using a radial combinerThe development of the SSPA amplifiers for SATCOM, and GBS will find direct insertion into Local Multi-point distribution Systems at 28-30 Ghz in which Princeton Microwave is currently active.