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Can FR4 be used at 5.8GHz? - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


James
Post subject: Can FR4 be used at 5.8GHz?
Unread postPosted: Fri Jul 08, 2005 1:43 pm

Does anybody have experience using FR4 at 5.8GHz?


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Guest
Post subject:
Unread postPosted: Sat Jul 09, 2005 12:33 am

Why not?. I used FR4 upto 17GHz. No more RT Duriod.


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IR
Post subject:
Unread postPosted: Sat Jul 09, 2005 3:58 am
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Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hello,

FR4 has a high loss due to its high TanD. Also FR4 has an unstable dielectric coefficient. That is working against you if you have to implement printed elements: Couplers, Filters, Baluns etc. The only motivation to use FR4 is only for low cost. A known solution is to combine between 2 types of substrates: FR4 and
ROGERS 4003/4050 for example. In this solution, you can implement the printed elements with the ROGERS and the rest of the design with FR4.

_________________
Best regards,

- IR


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James
Post subject: Thanks IR.
Unread postPosted: Mon Jul 11, 2005 12:53 pm

Right. Low cost is what I am looking for. I am using FR4 with 10 mil RO4350 now. Two risks come with using FR4 only. One is whether I can build power spliter/couplers/baluns on board. The other is will it have too much loss. Is there any PCB supplier who are very experience in doing FR4 PCB for RF application?


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IR
Post subject:
Unread postPosted: Mon Jul 11, 2005 2:14 pm
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Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hello James,

I don't think that the manufacturer should be experienced in doing FR4 for RF application. You should do the effort on a good PCB layout and pay attention to good layout practices - and there are plenty to follow.

Any medium to large PCB manufacturer with good workmanship quality will do the same on your RF PCB. You should ask the manufacturer to check the impedance of your PCB in the layers that carry the RF signals. The manufacturer usually provides a report of that test together with samples of the PCB.

Should you need more information, please let me know.

Good luck!!

_________________
Best regards,

- IR


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James
Post subject: Thank you IR
Unread postPosted: Tue Jul 12, 2005 5:37 pm

Thank you IR!


Posted  11/12/2012
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