View of 70m (230 ft.) <a href="https://en.wikipedia.org/wiki/spacecraft_communication" class="extiw" title="w:spacecraft communication">spacecraft communication</a> antenna at the <a href="https://en.wikipedia.org/wiki/Canberra_Deep_Space_Communication_Complex" class="extiw" title="en:Canberra Deep Space Communication Complex">Canberra Deep Space Communication Complex</a>, located outside Canberra, Australia.  It is one of the three complexes which comprise NASA's Deep Space Network. The other complexes are located in Goldstone, California, and Madrid, Spain.  This is a <a href="https://en.wikipedia.org/wiki/parabolic_antenna" class="extiw" title="w:parabolic antenna">parabolic antenna</a> with <a href="https://en.wikipedia.org/wiki/Cassegrain_antenna" class="extiw" title="w:Cassegrain antenna">Cassegrain</a> feed.  It operates on <a href="https://en.wikipedia.org/wiki/X_band" class="extiw" title="w:X band">X band</a> (8 - 12 GHz) with extremely high gain of about 70 dBi.  The incoming microwaves bounce off the large dish and are focused on the small white convex secondary reflector, which reflects them into the <a href="https://en.wikipedia.org/wiki/feed_horn" class="extiw" title="w:feed horn">feed horn</a> at the center of the dish.      The receiver uses extremely low noise amplifiers such as cryogenically cooled <a href="https://en.wikipedia.org/wiki/maser" class="extiw" title="w:maser">masers</a> or <a href="https://en.wikipedia.org/wiki/parametric_amplifier" class="extiw" title="w:parametric amplifier">parametric amplifiers</a> to detect the faint signals from spacecraft in the outer reaches of the Solar System.  The three flags in foreground are those of the nations hosting the three Deep Space Network sites.
NASA
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