On 2/26/14 12:44 AM, Hal Murray wrote:
rich...@karlquist.com said:
Solid dielectric cable and connectors of 3.5 mm size are mode limited to 18
GHz. That is why there is so much stuff rated at 18 GHz as opposed to 16 or
20 GHz.
Thanks. That's what I was looking for.
Wiki says that SMA works to 18 GHz and the 3.5 mm is good for 34 GHz.
http://en.wikipedia.org/wiki/SMA_connector#Variations
And, as pointed out earlier, the market is smaller, so volumes are
smaller, and driving the price down from being able to change to truly
mass production is harder.
There's also a manufacturing tolerance issue. The higher you go, the
tighter the mechanical tolerances get. I suspect there is a huge amount
of tooling out there for SMA connectors and other things of that size
where the machining tolerances are "good enough" for SMA and 18GHz, but
not "good enough" for higher.
That drives all sorts of things.
THere's also semiconductor parts. Lots and lots of stuff in the under
12-13 GHz range that are inexpensive. A fair amount up to 18-ish, and
then it sort of falls off.
There, it's driven by market, which in turn is driven by international
allocations. DBS satellites at 12-13 GHz is a high volume market, so
there's lots of things like MMIC low noise amplifiers. Likewise
anything around 2.45 or 5.1-5.8 GHz. You see a big break in RF
equipment model capability at 3GHz and 6GHz, and I suspect that's driven
by the desire to test cellphones and wifi and BT (<3 GHz) and
802.11a/802.11n, WiMax, etc at <6GHz.
Parts that are cheap and easy to use lead to interesting products like
the SignalHound spectrum analyzer, but I don't expect to see a 50GHz
SignalHound any time soon. ($900 for 4.4 GHz, $2k for 12.4GHz). You
could probably *build* a front end converter for a signal hound fairly
inexpensively, but the parts for, say, 32 GHz would cost as much as the
Signal Hound backend.
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