VHF/UHF receivers use one of a few standard intermediate frequencies. Is there a similar set of standard intermediate frequencies for microwave (around 3GHz) receivers?

As I understand it, the choice of IFs usually comes down to what filters are available and how easy it is to create an LO at the appropriate frequency. Is that the case for microwave receivers as well?

  • 1
    \$\begingroup\$ The reasons for selecting a particular IF (and its associated bandwidth) for microwave downconversion are the same as for UHF/VHF/HF frequencies. Availability hasn't much to do with it (at least in the commercial realm- you just have the parts custom made to fit your needs). Since most of the early uses of microwave spectrum were radar, line-of-sight communications (telephony), and satellite communications (L/S/C/X/Ku/Ka transponders), the particular requirements evolved from that background. \$\endgroup\$
    – user201365
    Dec 7, 2018 at 3:07
  • \$\begingroup\$ @isdi If you want to add that comment as an answer, I'll be happy to accept it. Seems to me that "there aren't any" is a good answer in itself. \$\endgroup\$ Dec 10, 2018 at 9:15

1 Answer 1


The early satellite TV receivers used a 70 MHz IF, to filter and amplify and limit the down converted signal.

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On the other hand, in the 1970s, there were satellite to satellite laser links, and the data streams ended up on earth and were recorded onto photographic film. To handle the downlink (not the space-based laser links), some radio methods were needed to handle clouds and other non-laser friendly issues.

The datarate was 700,000,000 bits per second.

I don't think 70MHz IFs (with +-5MHz bandwidth?) would suffice.

I do recall various MODEMS (back then, we called them bit-syncs) crafted to handle 150,000,000 bits per second in the early 1970s using ECL; some in the late 1970s even were adaptively equalized, using coax-delays and Gilbert-cell multipliers; these also functioned at 150,000,000 bits per second.

In the late 1970s I recall boxes providing nearly 1/2 GigaBit spaceborne. These likely used 5x or 10x the bitrate as the carrier, just so the antenna bandwidth and the antenna beam-forming, were practical.

  • \$\begingroup\$ I'm not sure why this was downvoted? It is only one example, but it seems like a good datapoint. \$\endgroup\$ Dec 8, 2018 at 8:59

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