I build them as needed. Nothing critical about that. Even unbalanced shielded loops are good for locating (say) coating process problems -- and you can throw them away without a qualm, later.
Cortland ====================== Original Message Follows ==================== >> Date: 01-Aug-00 06:57:16 MsgID: 1072-33989 ToID: 72146,373 From: [email protected] >INTERNET:[email protected] Subj: Re: Shielding Effectiveness - or when a dB is not a dB Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 1 List-Post: [email protected] Date: Tue, 01 Aug 2000 06:58:47 -0700 From: "Douglas C. Smith" <[email protected]> Reply-To: [email protected] Subject: Re: Shielding Effectiveness - or when a dB is not a dB Hi Cortland, It is good to know that others are using the technique. I have seen many misapplications of shielding numbers in selection of a material. Do you buy or build your loops? Doug Cortland Richmond wrote: > > I have been using plane shielded loops for over 15 years. Small magnetic > loops allow localizing defects to small areas and use of small samples. I > don't claim objective figures, but by comparing the material under test to > a known good shield (i.e.: galvanized iron sheet) and to air, one gets a > good feel for the merit of the material in hand. > > Cortland > > ====================== Original Message Follows ==================== > > >> Date: 31-Jul-00 20:53:05 MsgID: 1072-33864 ToID: 72146,373 > From: "Douglas C. Smith" >INTERNET:[email protected] > Subj: Shielding Effectiveness - or when a dB is not a dB > Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 1 > > Date: Mon, 31 Jul 2000 20:53:52 -0700 > From: "Douglas C. Smith" <[email protected]> > Subject: Shielding Effectiveness - or when a dB is not a dB > Reply-To: "Douglas C. Smith" <[email protected]> > > > > Hi All, > > Shielding effectiveness is normally measured using plane > waves (relatively far from the source). This method of > measurement for shielding effectivenes does not always > correspond to the way a shielding material is used. It is > especially true when shielding material is incorporated > into small products, such as the new wave of wireless > devices on the market. If you rely on shielding to keep > different parts of a product from interfering with each > other, correlation of specification to use is especially > important. > > The August 2000 Technical Tidbit on http://www.dsmith.org > (or http://emcesd.com) describes a simple method of > shielding effectiveness measurement that can be easily done > in the development laboratory. This measurement method can > give a better measure of shielding effectiveness that > industry standard measurement techniques when the shield is > close to the source being shielded. > > Has anyone here who is into shielding used something like > this method which uses magnetic field loops? > > Doug > -- > ----------------------------------------------------------- > ___ _ Doug Smith > \ / ) P.O. Box 1457 > ========= Los Gatos, CA 95031-1457 > _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 > / /\ \ ] / /\ \ Mobile: 408-858-4528 > | q-----( ) | o | Email: [email protected] > \ _ / ] \ _ / Website: http://www.dsmith.org > ----------------------------------------------------------- > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Jim Bacher: [email protected] > Michael Garretson: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > > ====================== End of Original Message ===================== > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Jim Bacher: [email protected] > Michael Garretson: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] -- ----------------------------------------------------------- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: [email protected] \ _ / ] \ _ / Website: http://www.dsmith.org ----------------------------------------------------------- ====================== End of Original Message ===================== ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
