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Re: Satellite Downlink Power Combiners?

I have done this both ways, using a high power combiner and using linear
amplifiers. If you select the high power combiner approach, you will
definitely lose in excess of 6 dB per port. Circulators on each port are
highly recommended, which adds additional loss and weight. The linear
amplifier approach is probably more practical and in the end could be the
smallest and lightest package. Either way winds up with allot of power. For
the class C combiner scenario, you would need a total of 80 watts of RF to
get 20 Watts (4 x 5watts) after the combiner. Assuming 70% efficiency thats
around 114 Watts of DC power. For the class A low level linear amp, you
still need 20 watts of RF power. Assuming an efficiency of 20%, you end up
with about 100 Watts of DC power. Keep in mind, in the linear scenario, the
amplifier must be operated around 3 to 6 dB away from saturation to keep the
IMD products down. This could reduce the efficiency as well.


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