wrote in news:1145727069.586990.95580
@j33g2000cwa.googlegroups.com:

What do you mean by simple receivers ? What are you trying to receive,
with what stability and sensitivity ? Amateurs have traditionally used
crystal-controlled downconverters in front of lower frequency
receivers, but this is generally suited only for receiving small
segments of spectrum and doesn't usually have a very small parts count.
The local oscillator usually involves several multiplier stages and
tunable filters. The performance can be very good though.


Something that can be built with 1 chip just to experiment for now.
From what I read, regular fiberglass boards don't work well above 1 GHz.
Where do you get teflon boards?

JJ

"JJ" wrote in message
...
wrote in news:1145727069.586990.95580
From what I read, regular fiberglass boards don't work well above 1 GHz.

That's a bit of an overgeneralization. We routinely use "generic" FR-4 to
3GHz, and you'll find that many wireless routers at 2.4GHz do as well. As
long as the paths are relatively short and you're just using the board to get
a signal from point A to point B, it works pretty well.

The folks who suggest you use Teflon or other high-quality board materials are
probably thinking of building distributed circuits on it -- stuff like
filters, where the board's loss (its Q) significantly impact how good your
filter's response is. (Building something like a bandpass WiFi filter --
~25MHz wide at ~2.45GHz -- on FR-4 using coupled lines is probably not such a
hot idea -- this would be a good test case to simulate.)

Where do you get teflon boards?

All the decent-sized board houses (e.g., Advanced Circuits, DDI, etc.) have
low-loss board materials available. Nelco (http://www.parknelco.com/) and
Rogers (http://www.rogers-corp.com/acm/index.htm) are two of the big players
here. We have many boards done in Nelco 4000-13, which is a "mid-loss"
material... only somewhat better than FR-4 when it comes to absolute loss, but
considerably better when it comes to the specs not drifting over process,
temperature, etc., all at a relatively small pricing premium.

If you can afford it, by all means, get low-loss boards. However, in many
cases in the low-GHz area you end up with more loss from items such as coax
cable, connectors, impedances mismatches, etc. than the PCB material itself.

---Joel Kolstad