NSA above 1 GHz becomes (technically spoken) less relevant , as it becomes increasingly easier to calibrate antennas as if they were used in free space. The short wavelength makes is easy to choose the antenna-antenna distance very short compared to the height of them. In this way reflections are most attenuated and close field coupling to the ground plane does not exist. This makes it very easy to measure emissions from EUT's in any standard (shielded) room as one is allowed to come closer to the EUT. Echo's and interference from other sources are to become irrelevant then. The extreme directivity of broadband horn antenna's add to this advantage. One may select the direction of measurement to the least environmental interference. Remember the close-field/far-field (lambda/2pi) transition determines the technical need to maintain a 3-10-30 meter distance (in addition to EUT size).
Developments are ongoing to allow the method of "partial illumination" also to be used for emission measurements on large EUT's. Regards, Gert Gremmen, (Ing) ce-test, qualified testing =============================================== Web presence http://www.cetest.nl CE-shop http://www.cetest.nl/ce_shop.htm /-/ Compliance testing is our core business /-/ =============================================== >>-----Original Message----- >>From: [email protected] [mailto:[email protected]]On Behalf >>Of [email protected] >>Sent: Thursday, January 04, 2001 2:54 PM >>To: Mike Cantwell >>Cc: [email protected] >>Subject: Re: NSA above 1 GHz >> >> >> >> >>Mike, in C63.4, the project number is 1-13.2. The contact is Michael >>Windler. >> >>[email protected] >> >>>From the latest C63 Newsletter: >> >>"The key issues being addressed in this project include ground plane >>influences, site reflections and practical frequency limits to the >>traditional method for normalized site attenuation (NSA) under 1000 MHz. >>There are five labs making various reflective ambient measurements >>(including placing absorber material on the ground plane between the >>transmitter and receive antennas)." >> >>================================================================== >>============================== >> >> >> >> >>Mike Cantwell <[email protected]> on 01/03/2001 02:06:20 PM >> >>Please respond to Mike Cantwell <[email protected]> >> >> >>To: "'[email protected]'" <[email protected]> >>cc: (bcc: Robert E. Heller/US-Corporate/3M/US) >>Subject: NSA above 1 GHz >> >> >> >> >> >>Does anyone know of any Normalized Site Attenuation measurements above 1 >>GHz? I'm specifically interested in whether or not ANSI C63.4 or CISPR-22 >>is >>planning this, and if so, is there any preliminary info? >> >>Any help would be greatly appreciated. >> >> >>Thanks, >> >>Mike Cantwell >> >>------------------------------------------- >>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] >> >> >> >> >> >> >> >> >> >>------------------------------------------- >>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] >> >> >>
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