Re: Transmission line-like resonances at ~30MHz
From: John Larkin (jjlarkin_at_highSNIPlandTHIStechPLEASEnology.com)
Date: 02/10/05
- Next message: nospam: "Re: Why is the ATX PSU designed to standby current?"
- Previous message: Rob Gaddi: "Re: Soldering TQFSOPNCD packages ;-)"
- In reply to: Chris Carlen: "Re: Transmission line-like resonances at ~30MHz"
- Next in thread: Chris Carlen: "Re: Transmission line-like resonances at ~30MHz"
- Reply: Chris Carlen: "Re: Transmission line-like resonances at ~30MHz"
- Messages sorted by: [ date ] [ thread ]
Date: Thu, 10 Feb 2005 10:07:40 -0800
On Thu, 10 Feb 2005 07:35:14 -0800, Chris Carlen
<crcarle@BOGUS.sandia.gov> wrote:
>Joel Kolstad wrote:
>> I have a design on an FR-4 PCB that has a few long traces on it, about 12"
>> each. When I examine those trace's responses on a network analyzer, they
>> have significant (>15dB) dips at 30MHz, then 90MHz, 150MHz, etc... this led
>> me to suspect that the traces were behaving like quarter wave transformers
>> (the traces have various components connected to them, but they're all
>> supposed to be pretty high impedances), but if I assume an effective
>> dielectric constant of ~2.35,
>
>
>I think FR-4 has mu_r = 4.7
Programs like Txline and Appcad will compute effective dielectric
constant. The classic 50-ohm microstrip on 0.062 FR4 has Eeff of about
3.4. Skinnier traces tend to be lower.
John
- Next message: nospam: "Re: Why is the ATX PSU designed to standby current?"
- Previous message: Rob Gaddi: "Re: Soldering TQFSOPNCD packages ;-)"
- In reply to: Chris Carlen: "Re: Transmission line-like resonances at ~30MHz"
- Next in thread: Chris Carlen: "Re: Transmission line-like resonances at ~30MHz"
- Reply: Chris Carlen: "Re: Transmission line-like resonances at ~30MHz"
- Messages sorted by: [ date ] [ thread ]
Relevant Pages
|
