[eagle] Re: Eagle Microwave Antenna Arrays -- mechanical concepts
antonio at qualcomm.com
Fri Mar 23 15:36:31 PST 2007
At 03:24 PM 3/23/2007, John B. Stephensen wrote:
>There are probably better phase shifters available. I just happened
>to see these while looking at an MA/COM catalog. LNA MMICs have a
>gain variation of about 3 dB and at least 1 dB of the variation is
>probably temperature related, so the phase shifter loss doesn't need
>to be controlled too precisely.
A related thought... My first thought was that the programmable
attenuator was an absurd complexity. I was reacting to the thought
that it was just there to fix this stupid feature of the phase
shifter. However, there will be other things that make the levels
slightly different at each antenna. Losses, splitter imbalances, god
knows what. A programmable attenuator per element could shim all
these things. Once per cycle, the software would just write a few
bits to each antenna element, some of the bits going to the digital
phaseshift chip, and some going to the digital attenuator
chip. Maybe the attenuator is a good thing.
Still... 3dB !!! Such a big phase shifter loss VARIATION with phase
is something we'd want to compensate for no matter what the LNA gain
variation with temperature or whatever was.
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