ED, Water based sites are referred to in CISPR 12 publication in the clause referring to radio interference tests on spark ignited, engine driven motor boat engines etc.
Sites could be salt or fresh water based, but my understanding is that salt based sites would improve measurement accuracy. But a stagnant salt water based site would have variable salt concentration and hence differing RF reflectivity with weather and temperature. Out in the sea would be better (!!) because of better temperature stability too. We would be dealing with the summation of "direct" and "reflected + refracted" rays and not just the sum of "direct" and "reflected" rays. Refraction is related to wavelength, so there would be a differing response to frequency. But at CISPR frequencies to 1GHz it wouldn't matter much. Higher frequencies would refract, possibly even get (Upper GHz) absorbed by water. In any case, the actual "ground reference plane in water" in a water based site would be considerably deeper than just the surface of the sea or sea level, just how deep would depend on the salt concentration. So, the depth of the site would be important too. Who knows, we could be using the site verification measurements in Dead Sea as our yardstick in the new millennium, or, salted igloos as TEM cells (with a nice stalactite/stalagmite as septum) or anechoics!! Regards Arun Kaore EMC Engineer ADI Limited Systems Group Test & Evaluation Centre Forrester Road, St Marys NSW 2760 P O Box: 315, St Marys NSW 1790 Tel: 61 2 9673 8375 Fax: 61 2 9673 8321 Email: [email protected] <mailto:[email protected]> -----Original Message----- From: Price, Ed [SMTP:[email protected]] <mailto:[SMTP:[email protected]]> Sent: Tuesday, 03 August, 1999 7:35 To: 'Arun Kaore'; '[email protected]' Subject: RE: cost effective EMC facility Arun: I was just struck by what you said about "setup a Sea Plane or a salt water based site" . Has anyone ever set up an OATS using salt water as the ground plane? Talk about excellent surface smoothness, easy to level and cheap material, plus simple repair! (Uhh, could we say it fixes itself?) Just what conductivity would be enough? Could we get enough conductivity before we reach salt saturation? I suppose the upper limit on surface area would be when we get to the point of the wind causing surface ripples. Or gravitational tides. Turntables might be a lot cheaper, too. Just a thin raft that floats. Seriously, has anyone tried this for an OATS? (I seem to recall the US Navy had a really big ship simulator here in San Diego, where they placed scale models of ships on a sheet-steel "sea" in order to model HF wire antennas.) Regards, Ed :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-): -):-):-):-):-):-):-):-):-):-):-):-):-):-):-) Ed Price [email protected] <mailto:[email protected]> Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 (Voice) 619-505-1502 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-): -):-):-):-):-):-):-):-):-):-):-):-):-):-):-) > -----Original Message----- > From: Arun Kaore [SMTP:[email protected]] <mailto:[SMTP:[email protected]]> > Sent: Sunday, August 01, 1999 6:05 PM > To: '[email protected]' > Subject: FW: cost effective EMC facility > > > IMHO, there is no cost effective EMC facility, but you don't have to spend > all your bucks all in the one day. A sound and well managed EMC business > growth program could see you through. > > Start off with pre compliance and eventually branch off into formal > compliance (by drafting up a Quality System to ISO 25 or whatever, a few > test procedures and a few Quality and third party Technical Audits) > > Buy a 2nd hand shielded room today with a view to lining it with ferrite > tiles and/or RAM material such that you meet the Radiated Immunity 16 > point > check for immunity and alternative sites 3 m NSA for emissions. Initial RE > prescans could be done here. > > Buy a 26 GHz cheap ($25000/-!!) analyser (without preselector) driven by > software for now and then go for a $100000/- preselectable receiver > suitable > for formal CISPR measurements and also MIL 462 related work. > > Start off with a chicken wire mesh car park OATS and improve later; not > much > hope in Singapore because of the ambients, but you could always go to > Malaysia or setup a Sea Plane or a salt water based site (you will get > very > good NSA, probably won't need NSA). > > Lastly, performing ESD, EFT and Surge tests in a shielded room/ anechoic > chamber will make you very popular among your colleagues because of the > additional filtering within the shielded room. > > > Regards > > Arun Kaore > EMC Engineer > > ADI Limited > Systems Group > Test & Evaluation Centre > Forrester Road, St Marys NSW 2760 > P O Box: 315, St Marys NSW 1790 > > Tel: 61 2 9673 8375 > Fax: 61 2 9673 8321 > Email: [email protected] <mailto:[email protected]> <mailto:[email protected] <mailto:[email protected]> > > > -----Original Message----- > From: Qu Pingyu [SMTP:[email protected]] <mailto:[SMTP:[email protected]]> <mailto:[SMTP:[email protected]] <mailto:[SMTP:[email protected]]> > > > Sent: Friday, 30 July, 1999 18:38 > To: 'emc' > Subject: cost effective EMC facility > > > Hello, everyone: > I posted an question several weeks ago asking about GTEM. Thanks those who > share with me your experience. I may not address my problem very clearly > thus I would like to come back to you one more time. > We are a R & D orgnization in Singapore mainly dealing with semiconductor > industry. Since there are some requirements from our industry partners in > the area of EMC design, we are considering setting up some EMC measurement > capabilities. At the intial stage, we will only consider equipment for > radiated emission/susceptibility testing. Our objective is to evaluate the > EMC performance of the product from our customers, being of PCB level or > system level. Based on those results, we can help our customers to improve > their product EMC design so that their product can pass the final > compliance > testing. The EUT could be small, such as integrated circuits on PCB, but > it > can also be large such as a PC. Due to our budget constraint, I think GTEM > maybe a good choice. Do you guys agree ? If not, any other suggestions ? > Thanks in advance. > Best Regards > Qu Pingyu > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
