Over the last two decades, the capability and implementation of mm-wave point-to-point radios has changed almost beyond recognition. A manually-tuned, waveguide-aficionado's delight has evolved into a highly manufacturable, field programmable terminal with lower cost, higher performance and much greater utility. These changes have depended largely on the availability and performance of GaAs Microwave Monolithic Integrated Circuits (MMICs). Waveguide mounted diodes of various types have been replaced by highly integrated receiver LNA-mixer, transmitter mixer-buffer and PA blocks manufactured in commercial foundries and packaged in SMT packages which can be machine assembled onto micro strip radio boards. At these frequencies, "split" configurations are required to minimise RF losses, so the microwave components are exposed to a severe temperature range in an outdoor environment and power efficiency becomes very important.
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