EMC Beginner Questions - Page 1
Forum section: electronics / beginners

author: facuadrado
author_rank: Newbie
timestamp: September 25, 2019, 05:22:29 am
content: Hi,My name is Felix. I'm currently studying at the Polytechnic University of Puerto Rico. We have an EMC Chamber that no one uses. I believe some students did some testings 3 years ago when it was built and that's it. At the moment there are no professors that have used one before so I really don't have someone to teach me. I want to learn more about EMC and would like try some simple experiments. I was told a simple experiment would be to evaluate how well is the chamber isolated. My question would be: Is there a particular topic in the forum for EMC Beginners, a sort off tutorial to get you EMC chamber tested. Maybe a book you might recommend?I have attached the inventory we have and some pictures of the chamber:Equipment Model No. DescriptionTektronix 2465 Digital OscilloscopeTektronix 2430 Digital OscilloscopeHP 8350 A Sweep OscillatorHP 4332A LCR MeterSolar Electronics Co. 8282-1 Transient Pulse Generator (Peak Output Volts 0-600)ETS-Lindgren FM 5004 Holaday EMF MeasurementCrown DC300A 2 Channel High Power AmplifierETS-Lindgren FP5000 Isotropic Electric Field Probe (two)Kalmus 102LC-CE Max Input .22Vrms, .31 V Peak, .62 Vp-pRohde & Schwarz Esib-7 EMI Test ReceiverAlliedSignal 6552-1A 100 Watt Solid State Audio AmplifierHP 11691D Directional Coupler 2-18GhzHP 8495B Attenuator / 70dB (various)Avcom NASA-1000A Network and Spectrum AnalyzerMarconi Intruments 2022D 10kHz-1Ghz Signal GeneratorHP 8447D Amplifier 0.1-1300MhzETS-Lindgren 491198-36 Field ProbeRohde & Schwarz R&S Elektra EMC Test SoftwareGreat Lakes 15-12423 Server HousingAPC Pro-1500 Back-upsAmetek 3000Ls Power Supply 400HzSorensen DCS40-30E Power Supply (28V)IFI EFG-3 ETS Lundgrenna- Antenna 0.01-220MhzEmco Double Ridged Guide AntennaHP 8673B Synthesized Signal GeneratorSolar Electronics Co. 9233-50-TS-50-N Line Impedance Stabilization Network (10KHz-50MHz) ((various))Emco 3708 AntennaEmco 3102 Conical Log Spiral (various)Solar Electronics Co. 9144-1N Current Injection Probe (10KHz-100MHz)Tegam 95236-1 10KHz- 100MHz Current Probe (various)Wavetronics 6002-04 Freq 1.7-2.6GHz6003-04 Freq. 2.6-3.95GHz6001-03 Freq. 1.12-1.7GHz6004-05 Freq. 3.95-5.85GHz6005-03 Freq. 5.85-8.2GHzScientific Atlanta 12-8.2 Standard Gain Horn12-12 Standard Gain Horn

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 25, 2019, 08:25:46 am
content: Very cool! Looks well equipped, and the enclosure isn't just thrown together, it's something like, a commercial kit, I'm guessing? You may have a hard time measuring its isolation.May be worth tying in some experiments with your curriculum. That would be topical, and easy to convince professors or department heads to do, I would think. Are you doing physics, wave mechanics, EM, radio communication, anything like that? Even AC steady state problems (intro EE stuff) can be analyzed with a few of those instruments.Full-on EMC is an outgrowth of electromagnetism and circuit and network theory, with a lot of practical experience thrown in. And because it is quantitative, a lot of metrology is involved as well -- summing the losses of a system, calibrating it; measuring the noise floor and ensuring adequate margin there; etc. The experience can be derived from theory, but is usually learned piecemeal, because most engineers never really understand the physics, it seems to me, and many are forced into doing EMC by doing a product design and then failing to pass the cert test. This is very much a commercial operation, and it may be difficult to make use of all that equipment for academic purposes alone.It would be a cool opportunity to reproduce famous historical experiments from Hertz, J.C. Bose and others, for example (basic wave mechanics: antennas, transmission and reception; polarization; reflection, diffraction; signal generators, maybe not the original spark generators, but there are some cute items like Gunn diodes: not actually diodes, but resistors that happen to sing in the GHz!). The equipment running up in the 10s GHz range can be used to demonstrate optics (refraction and reflection) with reasonably sized elements.If nothing else, it might be something to suggest to dept head, or administration, that they could consider opening the lab to commercial users, perhaps hiring a lead tech (preferably with direct EMC experience) to support that role. There probably aren't many test labs in PR, I would guess!? Then again, probably not many customers either.Tim

author: facuadrado
author_rank: Newbie
timestamp: September 25, 2019, 03:50:17 pm
content: Hey Tim,Thanks for the quick response! I forgot to mention that I'm an EE student. So far I've taken (related to the emc) the regular physics classes and the math (calcI - Deferential Equations), Electronics, Micro-controllers, VHDL, Circuit Analysis and a class of Electromagnetic Theory. I enjoy Math and Physics and working on a lab environment. I was doing an internship this last summer and was given a tour around the EMC chambers used to test NASA equipment that will be sent to space. I got excited that we had one here at the university but unfortunately there is no one here willing to give it a go. I hate to say this but professors here lack the interest that I have... That chamber has been sitting there doing nothing for 3 years. This is why I decided to try and figure this out myself(with your help). I will look into the experiments you mentioned. Thanks again for replying.

author: tonyalbus
author_rank: Super Contributor
timestamp: June 17, 2020, 12:36:09 pm
content: Quote from: facuadrado on September 25, 2019, 05:22:29 amHi can you get a hold on teh servicemanual, schematics of the Avcom NSA-1000A Network and Spectrum Analyzer ?

author: fcb
author_rank: Super Contributor
timestamp: June 17, 2020, 01:10:13 pm
content: Hi Felix.I'm assuming there are two rooms, the shielded room next to the anechoic chamber? Can you find a ratings plate on the chamber - probably worth trying to get the spec.Also, what sort of feed-throughs have you got between the two rooms and from each room to the outside world. Got power?Looking at the list of equipment, it does seem heavily biased towards susceptability testing of military/avionics gear and less about emissions.Probably start by putting something noisy (chinese iphone charger?) in the anechoic and pointing a log periodic at it, change orientations, rotate the DUT, run sweeps, etc.. Get a feel for it. Be careful if you try conducted tests - make sure you pad the front end of that esib-7, treat it like a princess!