Home based EMC measurements

J

Joe.G

Guest
Hi All,

I have a spec analyser and I looking for suggestions
on antennas and comb generators within an afordable budget..

I have seen some scanner antenna's that are log periodic that have a wide
bandwidth.

The main goal is to get some idea if my product is
radiatating somewhere near the EMC limits or not.

Thanks in advance.

Joseph
 
In article <4261c5eb$0$12415$afc38c87@news.optusnet.com.au>,
Joe.G <joe.gXSPAMX@optusnet.com.au> wrote:
Hi All,

I have a spec analyser and I looking for suggestions
on antennas and comb generators within an afordable budget..

I have seen some scanner antenna's that are log periodic that have a wide
bandwidth.

The main goal is to get some idea if my product is
radiatating somewhere near the EMC limits or not.

Thanks in advance.
One problem is finding an environment (chamber/freespace) that is
free from other sources of RF so you can be certain if it's your
equipment that is emitting or not. I.e. you may have to build a
Farraday cage.

Later, -ingo
--
/* Ingo Cyliax, cyliax@ezcomm.com, Tel: 812-391-0895 */
 
Joe.G wrote:

Hi All,

I have a spec analyser and I looking for suggestions
on antennas and comb generators within an afordable budget..

I have seen some scanner antenna's that are log periodic that have a wide
bandwidth.

The main goal is to get some idea if my product is
radiatating somewhere near the EMC limits or not.

Thanks in advance.

Joseph


The antennas need a calibration curve (sensitivity VS frequency) to
be useful.
 
Ingo Cyliax wrote:

In article <4261c5eb$0$12415$afc38c87@news.optusnet.com.au>,
Joe.G <joe.gXSPAMX@optusnet.com.au> wrote:
Hi All,

I have a spec analyser and I looking for suggestions
on antennas and comb generators within an afordable budget..

I have seen some scanner antenna's that are log periodic that have a wide
bandwidth.

The main goal is to get some idea if my product is
radiatating somewhere near the EMC limits or not.

Thanks in advance.

One problem is finding an environment (chamber/freespace) that is
free from other sources of RF so you can be certain if it's your
equipment that is emitting or not. I.e. you may have to build a
Farraday cage.
The simple answer is to listen to the output of the receiver and switch the
EUT off and on - that'll determine where the emission is coming from.


Graham
 
On Sun, 17 Apr 2005 12:12:35 +1000, "Joe.G" <joe.g@optusnet.com.au>
wrote:

Hi All,

I have a spec analyser and I looking for suggestions
on antennas and comb generators within an afordable budget..

I have seen some scanner antenna's that are log periodic that have a wide
bandwidth.

The main goal is to get some idea if my product is
radiatating somewhere near the EMC limits or not.

Thanks in advance.

Joseph
These guys have some neat looking stuff:

http://www.electrosmog.com/



John
 
On Sun, 17 Apr 2005 10:54:50 -0700, in sci.electronics.design John
Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sun, 17 Apr 2005 12:12:35 +1000, "Joe.G" <joe.g@optusnet.com.au
wrote:

Hi All,

I have a spec analyser and I looking for suggestions
on antennas and comb generators within an afordable budget..

I have seen some scanner antenna's that are log periodic that have a wide
bandwidth.

The main goal is to get some idea if my product is
radiatating somewhere near the EMC limits or not.

Thanks in advance.

Joseph


These guys have some neat looking stuff:

http://www.electrosmog.com/



John
what an utterly confusing website, I'm looking for something like
this, whatever it is......


martin

After the first death, there is no other.
(Dylan Thomas)
 
On Mon, 18 Apr 2005 00:00:59 +0200, martin griffith
<martingriffith@XXyahoo.co.uk> wrote:

On Sun, 17 Apr 2005 10:54:50 -0700, in sci.electronics.design John
Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sun, 17 Apr 2005 12:12:35 +1000, "Joe.G" <joe.g@optusnet.com.au
wrote:

Hi All,

I have a spec analyser and I looking for suggestions
on antennas and comb generators within an afordable budget..

I have seen some scanner antenna's that are log periodic that have a wide
bandwidth.

The main goal is to get some idea if my product is
radiatating somewhere near the EMC limits or not.

Thanks in advance.

Joseph


These guys have some neat looking stuff:

http://www.electrosmog.com/



John
what an utterly confusing website, I'm looking for something like
this, whatever it is......
No argument there. Try this...

http://home.t-online.de/home/electrosmog.com/Antennas.htm


John
 
What if a get a Comb generator calibtated at a OATs test site.

Then I can do relative measurements regardless of antenna cable loss etc.

Meansure the comb freq / level and compare to the OATs test site results.

Provided the RF comb frequencies are up near the limits.

Then I can know weather to worry about passing the limits by a large safe
margin etc.

Joseph

"Joe.G" <joe.g@optusnet.com.au> wrote in message
news:4261c5eb$0$12415$afc38c87@news.optusnet.com.au...
Hi All,

I have a spec analyser and I looking for suggestions
on antennas and comb generators within an afordable budget..

I have seen some scanner antenna's that are log periodic that have a wide
bandwidth.

The main goal is to get some idea if my product is
radiatating somewhere near the EMC limits or not.

Thanks in advance.

Joseph
 
Some colleagues gave me a good tip.

They can do EMC testing with proper kit, but before you submit stuff for
expensive testing you can detect most of the gross RF leaks just by waving a
cheap AM radio around it.

Passing that test saves a wasted day of expensive EMC testing.
 
Hi Paul,
Are the suich things as wide band noise generators 10kHz to 1GHz for EMC
testing.

I hadn't seen andy around.

Any pointers to wide band noise genators would be appreciated (kits /
project and pro gear).

Regards
Joseph


"Paul Mathews" <optoeng@pioneernet.net> wrote in message
news:1113922504.414788.103810@o13g2000cwo.googlegroups.com...
Comb generator approach is OK to the extent that you approximate an
open area test site. Faraday enclosures can have quite strong
resonances between comb peaks. Noise generators are the preferred
signal source, since standing waves aren't such a problem.
Paul Mathews
 
I read in sci.electronics.design that Joe.G <joe.g@optusnet.com.au>
wrote (in <42663c19$0$10303$afc38c87@news.optusnet.com.au>) about 'Home
based EMC measurements', on Wed, 20 Apr 2005:
Are the suich things as wide band noise generators 10kHz to 1GHz for
EMC testing.

I hadn't seen andy around.

Any pointers to wide band noise genators would be appreciated (kits /
project and pro gear).
ARRL or RSGB Handbook (if possible, both). Look for 'noise diodes'.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
Joe.G wrote:
Hi Paul,
Are the suich things as wide band noise generators 10kHz to 1GHz for EMC
testing.

I hadn't seen andy around.

Any pointers to wide band noise genators would be appreciated (kits /
project and pro gear).
<http://www.yorkemc.co.uk/instrumentation/>

Paul Burke
 
Ingo Cyliax wrote:
In article <4261c5eb$0$12415$afc38c87@news.optusnet.com.au>,
Joe.G <joe.gXSPAMX@optusnet.com.au> wrote:

Hi All,

I have a spec analyser and I looking for suggestions
on antennas and comb generators within an afordable budget..

I have seen some scanner antenna's that are log periodic that have a wide
bandwidth.

The main goal is to get some idea if my product is
radiatating somewhere near the EMC limits or not.

Thanks in advance.


One problem is finding an environment (chamber/freespace) that is
free from other sources of RF so you can be certain if it's your
equipment that is emitting or not. I.e. you may have to build a
Farraday cage.

Later, -ingo
A 20' container works nicely. Reefers are better, they are a lot warmer
in winter.

Cheers
Terry
 
Kryten wrote:
Some colleagues gave me a good tip.

They can do EMC testing with proper kit, but before you submit stuff for
expensive testing you can detect most of the gross RF leaks just by waving a
cheap AM radio around it.

Passing that test saves a wasted day of expensive EMC testing.
Bruce Carsten's EMI sniffer probe is good there, too. Use with a tunable
receiver, can be very cheap.

I have a mate who's company has an EMC test setup (alas no anechoic
chamber) and thus have 4 hacks at it:

1) design for minimum EMI
2) sniffer probe tests.
3) use their test-setup, only $100/hr
4) then pay big bucks for the real deal.

Cheers
Terry
 
Terry Given wrote:
A 20' container works nicely. Reefers are better, they are a lot warmer
in winter.
I find hot toddies warmer in winter, as the reefer doesn't really give
out much heat.
 

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