Tim, The best advice is to set up the chicken wire as a ground plane and take full sets of NSA. Perform these measurements just as if you were on the completed site, including keeping yourself and your measurement equipment out of the ellipse. If you don't meet NSA, then re-orient the site and do it again until you do. Once you get good data, build the site in that spot in that orientation. If you can't get good data, then it might be career limiting to put a site there. Fix the problems BEFORE you invest in the site. Keep in mind that the building you put up to house the people doing the testing may interfere with the NSA in the final version. Rent a U-Haul and park it where the building will end up. If that big hunk of metal still lets you obtain good NSA data, then the building should be OK too. Take the measurements and don't guess, a good site survey runs rings around guessing and conjecture. Also, once you determine the site is OK, take the time to perform an ambient survey and drive around the area to see what's there. There may be other gotchas! And just to stress the importance, take measurements, take measurements, and take measurements. Good Luck, Mike
From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of emcp...@aol.com Sent: Wednesday, 18 June, 2003 6:13 PM To: emc-p...@majordomo.ieee.org Subject: Question about OATS Hello, I'm building an open area test site, and have some questions about the ellipse and ground plane. I'm following ANSI C63.7:1992. I have used several OATS and done site attenuation before, but this is the first time building one from the ground up. I'm building a 10 Meter OATS with a 14 foot turntable. Figure 1 in ANSI C63.7 says that the minor diameter of the ellipse shall be 17.3 Meters and the major diameter shall be 20 meters for a 10 meter site. For the ground plane, Table 1 in ANSI C63.7 says for a 10 meter site, the width shall be 12 meters and the length shall be 15.3 meters. The corners of the ground plane will be outside the ellipse. Is this ok, or should the ground plane be smaller, to fit inside the ellipse? What would be the minimum ground plane size I could use for this 10 meter site with a 14 foot turntable? Also, there is a chain-link fence running parallel with the proposed site, but the fence is just outside the ellipse. Would there be any problems with site attenuation? I can alter the ellipse so the site is not exactly parallel with the fence. (Antenna would be somewhat diagonal to the fence) Would that help avoid any problems? Thanks in advance for any input you may have. Tim Pierce EMC Engineer
