Near Field Probes. - Page 1
Forum section: electronics / testgear

author: kumar
author_rank: Contributor
timestamp: August 16, 2013, 12:15:50 pm
content: Hi,I want to make near field probes using a semi rigid coax cable. There are a few posts about it but only the final photograph is displayed. There is no step-by-step procedure given. Can any one please help me?

author: Carrington
author_rank: Super Contributor
timestamp: August 16, 2013, 12:34:03 pm
content: I also I have interest, I hope someone contributes.

author: Rufus
author_rank: Super Contributor
timestamp: August 16, 2013, 02:15:41 pm
content: Quote from: kumar on August 16, 2013, 12:15:50 pmThey are just a loop of the centre conductor using the screen of the cable as an electrical shield.Cut back a little bit of the screen and insulator so you can short the core and screen with solder. Form a loop and solder the core and screen back onto the screen. A little copper tape wrapped and soldered around the joint might make a nicer job.Now you have a screened loop but the screen is also a loop which you need to break. With a small hacksaw or needle file carefully cut a slot in the screen trying to leave the insulator (and definitely the core intact). Doesn't really matter where the slot is but middle is easiest.Find some way to insulate the whole thing to avoid the risk of shorting live circuits to ground. Multiple coats of paint or maybe epoxy glue/resin or potting compound, or something. I used hot melt glue on the ones I made.

author: fpliuzzi
author_rank: Regular Contributor
timestamp: August 16, 2013, 06:44:11 pm
content: The center probe in Figure 1 of the included illustration shows the type of probe that Rufus has described the construction steps for above. This illustration was helpful to me when I built my set of H-field and E-field probes.Regards,Frankps The 60 minute Rohde & Schwarz EMC presentation over at vimeo was interesting. Thanks.

author: eurofox
author_rank: Unknown
timestamp: August 16, 2013, 10:56:15 pm
content: There is a excellent book about this subject TESTING FOR EMC COMPLIANCE Approaches and TechniquesYou can buy itIncluding as well the detail how to build and use the probes.Eurofox

author: fpliuzzi
author_rank: Regular Contributor
timestamp: August 16, 2013, 11:18:50 pm
content: I just downloaded your recommended book "TESTING FOR EMC COMPLIANCE Approaches and Techniques" in pdf form for free. Should make for some interesting reading. Thanks.Another book on the subject of EMC that I purchased quite a few years ago is "Noise Reduction Techniques in Electronic Systems", by Henry W. Ott (2nd edition). I found this book quite helpful.Regards,Frank

author: eurofox
author_rank: Unknown
timestamp: August 17, 2013, 01:18:09 pm
content: Quote from: fpliuzzi on August 16, 2013, 11:18:50 pmI could find the book you advice on the netLook interesting as well, thanks for it. Now we can start to build our probes.In attachment an interesting file with a lot of information about tools from a specialist in this field.Eurofox

author: Carrington
author_rank: Super Contributor
timestamp: August 18, 2013, 12:12:13 am
content: http://www.millertechinc.com/pdf_files/MTI%20TN101%20Simplest%20EMC%20Magnetic%20Field%20Probe.htm

author: fpliuzzi
author_rank: Regular Contributor
timestamp: August 18, 2013, 02:07:29 am
content: Speaking of simple to construct probes; EMC/ESD consultant Douglas C. Smith made a handy little magnetic field loop probe from an insulated paperclip and a female BNC coupler. The probe is described on the following pages of his site.http://emcesd.com/tt080699.htmhttp://emcesd.com/tt040600.htmThis short video shows the ultra-simple probe being used for sniffing switch-mode power supply noise (note the use of a clamp-on type ferrite core on the probe end of his 50 ohm cable).Doug's site contains quite a bit of practical EMC/ESD info (http://emcesd.com/)Regards,Frank