Millimeter Wave Spatial Power Combining Techniques

Many millimeter wave radar and communications applicatins require total RF output power of 30W or more. Since one solid state three-terminal amplifier can deliver less than a Wattat these frequencies, the outputs of several devices must be combined to achieve the power levels desired. Conventional power combining circuits become expensive and ineffecient for large numbers of devices. However, spatial power combining via quasioptical techniques improves efficiency by replacing much of the transmission line with lenses and feeds, thus allowing arrays with many amplifiers to give a net power increase. Our study will include practical tradeoffs of a quasioptical power combiner having an output power goal of 10-100W in the millimeter wave range. The study will include improved lenses, feeds and planar media giving optimum efficiency, size, weight, thermal performance, impedance matching and manufacturability. Phase I will comprise a goal definition and block diagram followed by a study of tradeoffs in packing density, area, volume, antennas and amplifier transmission media. The prototype we design in Phase I will be built in Phase II. These devices can be commercialized in automobile collision avoidance radars and all weather landing systems, already under development at Millitech.