On Nov 5, 6:21 am, David wrote:
On Sun, 04 Nov 2007 00:17:26 -0000, wrote:
On Nov 3, 5:49 pm, Telamon
wrote:
In article .com,

wrote:
If you need to prototype or build a lumped element RF filter, check
out the RF Filter PCBs at RF Bites.

http://www.rfbites.com

Those are not very good coax to PCB connectors. You can do better. Must
be pretty low frequency stuff ( 1 GHz ) if you are using FR4.

--
Telamon
Ventura, California

Connectors are rated to 12GHz.

FR-4 is good up to 3.5GHz, then it starts to fall apart.

http://en.wikipedia.org/wiki/FR4- Hide quoted text -

- Show quoted text -

Hi David,

Good article. I partially agree with Talamon that FR4 is not ideal
over 1GHz, if you have the budget for Roger's material and the specs
that necessitate such performance in your substrate. In the commercial
world, you would have a hard time justifying such an expense, so most
designers have to eat the performance issues and work a little harder
to develop more robust designs to handle the gross tolerance swings. I
would challenge anyone to find a PCS cell phone (1.9GHz) or a
commercial GPS with Roger's material. When I said that the FR-4
material was good up to 3.5GHz, that means I am getting good rejection
in my filters up to that frequency. I wouldn't design my passband to
be anything much over 2 GHz. Isn't there a saying that goes something
like, "Any average Engineer can design a $50,000 car, it takes a good
Engineer to design a $15,000 car." Food for thought.

FH