Regarding elevated OATS, a San Diego compliance test lab, EESI, constructed their own 10 meter site using a wood structure about 24" above ground level. I suggest you contact Dr. John Lavery of EESI at 619-259-4944 or tech...@eesi.com.
Ed ------------------------ From: "WOODS, RICHARD" <wo...@sensormatic.com> Subject: RE: ANSI C63.4 Date: Thu, 12 Nov 1998 14:23:39 -0500 To: emc-p...@ieee.org > I have no personal experience with raised sites, but I do know of folks that > skimped on the size of their ground planes when they were on the surface, > and they could not pass. I made my comments based upon that input and the > following. > > According to C63.7 Section 6.1, " . . . it may be prudent to have the > capability to extend the rectangular or trapezoidal dimensions of the ground > plane up to or larger than the dimensions of the Fresnel ellipse. This is > especially important for ground planes that are elevated above the > surrounding surfaces." > > ---------- > From: b...@namg.us.anritsu.com [SMTP:b...@namg.us.anritsu.com] > Sent: Thursday, November 12, 1998 11:06 AM > To: emc-p...@ieee.org > Subject: RE: ANSI C63.4 > > Hi Richard, > > Would you please explain in detail what you said "Raising your > ground plane > above ground level is not recommended as it tends to create ground > discontinuities at the edge of the plane." in the 2nd paragraph of > your > following article. To my limited knowledge, people don't have > problem with > OATS atop their buildings. > > It seems to me that the discontinuities at the edge of the plane > exist on > every OATS, including those on a level with ground. ANSI C63.7 > already > considers it. The OATS with ground plane above ground level is not > an > exception of the consideration. > > Thank you. > Best Regards, > Barry Ma > > > ------------- > Original Text > From: "WOODS, RICHARD" <wo...@sensormatic.com>, on 11/11/98 1:21 PM: > Consult C63.7, "Guide for Construction of Open-Area Test Sites. We > built > our > site according to the guidelines with two exceptions: we soldered > the > ground > plane sections at about 6 inches and we made the plane size slightly > larger > than the recommendations. We passed the first time. I recommend the > increased size. > > Raising your ground plane above ground level is not recommended as > it tends > to create ground discontinuities at the edge of the plane. For > example, > this > can be a problem for OATS on top of buildings. This problem can be > corrected > by increasing the size of the plane. > > We run our cables over the ground plane and do not have a problem. > > Our OATS is in on the edge of a woods with trees on two sides and > water on > two sides. On the water sides, we have bushes to "hide" the site > (required > by the building code). We have not noticed a problem. > > Re how far way an object must be: I saw a film produced by HP where > they > had > a metal fence far outside the ellipse. They claimed that they could > see > variations in the reading when the wind moved the fence. > > ---------- > From: randall.flind...@emulex.com > [SMTP:randall.flind...@emulex.com] on behalf of Flinders, Randall > Sent: Wednesday, November 11, 1998 12:44 PM > To: 'emc-pstc' > Subject: ANSI C63.4 > > Greetings EMC Professionals! > > 2) Extending the width of the ground plane to 11.4 > meters. > > I have four questions to pose to the group: > > Question #1 - Does anyone have experience with an > OATS where > the ground plane is covered with concrete? What effect does this > have on > the performance of the site? > > Question #2 - ANSI C63.4:1992 does not specify the > minimum > size of the ground plane. Is there a guideline, or can someone tell > me > from > experience, what the minimum size should be? > > Question #3 - Does anyone have any feelings on what > the > effect of running the COAX and Power Cables on top of the Ground > Plane can > have on the site performance? Would It be better to raise the > ground plane > off the ground (on a wooded platform) in order to run all of the > cables > under the GRP? > > Question #4 - Although there are several trees with > in the > 10 meter Ellipse, they are located at the very edges of the Ellipse. > However, there are raised concrete curb planters and waist-high > hedges that > are well within the Ellipse. Can I expect these items to cause > significant > site abnormalities? Also, how far away does a metal object need to > be > before I can consider it safe from causing abnormalities due to > reflections? > > Any insight or suggestions on this matter would be > greatly > appreciated. Thanks for your time. > > Regards, > > > Randy Flinders > EMC Engineer > Emulex Network Systems > (714) 513-8012 > randall.flind...@emulex.com > -------------------------- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 11/12/1998 Time: 14:19:52 -------------------------- --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
