The roof alternative has been done more than a few times. Emaco (now part of TUVPS) in San Diego had a pair of pneumatic lifts which travelled from their second floor through the roof. The test specimen and antenna could be set up on their respective elevators, pushed up through the roof, and come to rest level with the roof ground plane.
I imagine that they did have some problems with weathering of conductive interfaces and water leakage, but it did serve them well for a few years. BTW, I agree that the "parking lot" option is better than trying to live with a test site WITHIN a commercial office structure. There have been several posters who already described the problems found inside the building. Some of the problems with a parking lot site are: 1. Sometimes the cars encroach on the site. 2. You have to schlep all your stuff out to the site, and back again at night. 3. Sometimes, your utilities get mysteriously shut off, necessitating a call to your plant facilities guy (for a big company; for little companies, you get to look for the breaker yourself). 4. Flooding. 5. Wind can knock over your test antenna mast. Securing the mast each night adds another housekeeping task. 6. Sunburn. (If I'm gonna get sunburned, let it be with a yacht beneath my feet.) 7. Ants and rodents. (You are only one step short of a picnic.) 8. Snow. Ice. Wind chill factor. (Enough said.) Ed Ed ------------------------ From: Gary McInturff <[email protected]> Subject: RE: Precompliance Testing Date: Mon, 3 May 1999 12:11:30 -0700 To: 'Brent DeWitt' <[email protected]>, Allen Tudor <[email protected]>, [email protected] > I'll agree with Brent, and others, the headaches of a metal room or the > metal studs et al, in a building are going to make you pull your hair out. > But there is an alternative to the parking lot. You may want to consider the > roof. The ground reference can be put up there as well, especially if you > are doing pre-compliance stuff. You don't have to give up parking space - > which is sure to irate somebody. The roof gets a little hot, but that only > gives you the opportunity to work in your cutoffs, and showing up to a > meeting with the suits dressed like this is always good for a laugh! > Gary > > -----Original Message----- > From: Brent DeWitt [SMTP:[email protected]] > Sent: Friday, April 23, 1999 7:12 PM > To: Allen Tudor; [email protected] > Subject: RE: Precompliance Testing > > Allen, > > From bunches of years of designing and using sites, what I would > suggest is, > IMHO, use the money to reserve a large space in the parking lot free > of > obstacles. Current construction techniques in buildings use lots of > steel > "2x4s" for the walls and there will likely be steel in the floor > above you. > All of these contribute to resonances in the emissions measurements > that are > far too difficult to want to deal with. The best way to do radiated > measurements is to be a minimalist. Get as far away from any > structure as > you can, put down a simple hardware cloth ground plane and throw a > nylon > tent over the product if it rains. > > Best regards, > > Brent DeWitt > Datex-Ohmeda Medical > Louisville, CO > > > > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]]On Behalf Of Allen Tudor > > Sent: Friday, April 23, 1999 1:27 PM > > To: [email protected] > > Subject: Precompliance Testing > > > > > > Our division is in the process of constructing a new building. I > > have been told that I will be given a room in which to make > > pre-compliance radiated emissions measurements. However, ferrite > > tiles or cones are out of the question (I have been told that I > > can hang "chicken-wire" on the walls if I want to). > > > > Even though I am restricted in how much money can be spent, I > > have the luxury of designing in features as the building is being > > constructed. > > > > At a bare minimum, I think we should lay sheet metal or grid-wire > > on the floor after the concrete is poured. This ground plane > > should be grounded at each corner by ground rods. I am thinking > > that if there is no steel framework near the room, this may > > provide fairly good results. > > > > I would appreciate any recommendations on other cheap features > > that I can design in while the building is under construction. > > Also, what is the minimum size the room should be? How about > > power wiring in the walls and in the ceiling. Should any > > measures be taken to prevent radiated energy from coupling into > > power wiring? > > > > Perfection is not the key issue here: repeatability is. We have > > a local certified lab that I can compare my measurements with. > > Once the room is complete, I can repeat my measurements at the > > certified lab and develop the necessary correction factors. > > > > By the way, my product is dc powered shelf-level telecom > equipment. > > > > Again, any advice will be appreciated. > > > > Thanks in advance. > > > > > > Allen Tudor, Compliance Engineer > > PairGain Technologies tel: (919)875-3382 > > 2431-153 Spring Forest Rd. fax: (919)876-1817 > > Raleigh, NC 27615 email: > > [email protected] -------------------------- Ed Price [email protected] Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: [email protected] Date: 05/03/1999 Time: 13:37:40 Military & Avionics EMC Services Our Specialty Also Environmental / Metrology / Reliability -------------------------- --------- 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).
