Charles,
You can do the same thing that ED PRICE suggested if your spectrum analyzer
has a tracking generator option installed. Just replace the signal
generator by the tracking generator.
We have characterized ferrite clamps and such in the same manner.
Best Regards,
Scott Mee
Johnson Controls Inc.
Automotive Systems Group
EMC Product Compliance
616.394.2565
[email protected]
[email protected]
Sent by: To:
[email protected], [email protected]
owner-emc-pstc@majordo cc:
mo.ieee.org Subject: RE: Measuring a
ferrite performance
12/18/2003 02:42 PM
Please respond to
ED.PRICE
From: Grasso, Charles [mailto:[email protected]]
Sent: Thursday, December 18, 2003 9:40 AM
To: '[email protected]'
Subject: Measuring a ferrite performance
Greetings all:
I have a requirement to test the performance of ferrite bead (one that
that can fit over a power cord) to 500MHz for qualification of
alternate vendors.
I have an impedance analyzer - but it only goes to 40MHz. Does anyone
have a good way to verify ferrite impedance.??
Thanks
Best Regards
Charles Grasso
Senior Compliance Engineer
Echostar Communications Corp.
Tel: 303-706-5467
Fax: 303-799-6222
Cell: 303-204-2974
Email: [email protected];
Email Alternate: [email protected]
Chuck:
Assuming that you have a signal generator and a spectrum analyzer, you
could try the following:
1. Get a small RF project box. Mount two N or BNC or SMA coax connectors on
opposite walls of the box. Solder a short wire directly from one coax
connector center pin to the other.
2. Decide on system impedance. If 50 ohms is OK, then just connect a 3 dB
attenuator to each of the coax connectors. If you want another impedance,
then put appropriate resistors (carbon comp preferred) into the project
box.
3. Connect the signal generator to one attenuator, and the spectrum
analyzer to the other.
4. Now set the generator to 0 dBm and sweep or step the frequency range,
noting the spectrum analyzer response.
5. Now open the box, break the wire, thread the bead onto the wire, and
re-solder the wire.
6. Repeat step 4. The amplitude differences will be the insertion loss due
to the bead performance.
7. Repeat steps 5 & 6 with any other bead samples.
This isn't an exhaustive test, but it's a good A to B comparison of RF
loss.
Ed
Ed Price
[email protected] WB6WSN
NARTE Certified EMC Engineer & Technician
Electromagnetic Compatibility Lab
Cubic Defense Applications
San Diego, CA USA
858-505-2780 (Voice)
858-505-1583 (Fax)
Military & Avionics EMC Is Our Specialty
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