building an EMC OATS

[youcefh]

Hi..
we are thinking to buy material for EMC open area testing site...we need to measure and locate the EM emissions on vehicles ... which material do we need to realize this test ?? such as which kind of antennas..spectrum analyzers ...??? thnx for ur help

 

[WimRFP]

Hello, I would start with reading a relevant EMC standard/recommendation for your application. This mostly shows a measurement setup with requirements for the equipment and the OATS.

Is your setup for only finding sources of EMC (to avoid interference in on-board RF equipment), precompliance or compliance measurements, as this makes a difference?

If you think that you need to test other equipment/systems also (for example Information and Telecommunication Equipment), you may buy an ITE EMC standard also (here EN 55022).

A complete other setup is required for measuring the effect of RF emissions on car electronics (RF immunity measurements). Such measurements require high power amplifiers and (directional) antennas to generate the required E-fields.

 

[youcefh]

Hi wimRF ..thnx for ur help..
our setup is only for finding sources of EMC ....can you provide me some examples about the directional antennas for measuring the RF emissions from car ? what r the requirements for such a test?

 

[WimRFP]

If you only want to find (physicaly locate) the sources where the EMI is generated, you can better invest in near field probes witgh a descent spectrum analyzer. You can think of magnetic loops, E-field probes, current probes, Bowtie antenna (for the UHF part of spectrum), etc. You can find the source with the small probes.

As locating a source of EMI doesn't require accurate equipment, you can make many probes yourself. Search for EMC probes DIY (DIY = Do It Yourself) and you will find relevant info. For locating the source you don't need a real EMC measurement receiver, a descent spectrum analyser is good enough. Be careful when buying ver low-end equipment as the dynamic range and spurious response may not be sufficient. This may result in finding things that aren't there, but are generated by the equipment itself.

If you want to find the frequency range where you exceed the limit, then you need at least a pre-compliance setup and you need to know the standard that is relevant for you. The standard specifies frequency range, measuring distance and height, soil conditions (soil or conducting plate/mesh), polarization, properties of detectors, etc.

So I think that you should start with studying the relevant standards. Then you are better informed to select equipment that does the job for a reasonable price.

To get an idea of antenna equipment you may visit:
https://www.ets-lindgren.com
https://www.com-power.com/antennas.html

These are just examples, there are many more companies supplying (calibrated) antennas.

As the "sensitivity" (E/Vout) varies with frequency, modern spectrum analyzers or measuring receivers enable you to enter the antenna parameters into the equipment so that you don't have to do the math manually.

 

[youcefh]

thnx WimRFP. it was very helpful ...
what to do for studying the relevant standards ?? it consists on what ?

 

[WimRFP]

You may google for CISPR 12 and CISPR 25. Such a search will also guide you to relevant ISO/SAE standards. These documents aren't free, but sometimes somebody leaves them on the internet, or you can find lectures that covers these standards so you will have some idea for the OATS (CISPR 12) and antennas

Why would you measure emissions? Are you manufacturer or do you need to solve EMC problems in cars (for example when installing communication equipment)?

Note that around the world there are several standards in use (also standards developed by car/engine producers). So If you need to measure for compliance, you need to know what standard is applicable for your market/client.

 

[youcefh]

yeah .. we need to solve EMC problems in cars when installing some communication equipment and other electronics systems .....like what is the best place for each equipment in the car to have no or less emc problems ??..

 

[youcefh]

OATS emc testing lab......

Hi every one...

i wanna know what are the needed materials and equipments for constructing an OATS emc lab....can some one help to explain what r the steps for building this lab ??

thnx ...