I have to confess to complete ignorance here. I had no idea that the measurements made during a height search were averaged. I though the NSA curve was based on a specular reflection from a perfect ground plane, in which case only the peak measurement during a height scan could correlate to the NSA curve. Could someone on the list explain how correlation is achieved through averaging?
> From: [email protected] > Reply-To: [email protected] > Date: Mon, 23 Jun 2003 10:40:29 -0600 > To: <[email protected]>, <[email protected]>, <[email protected]> > Subject: RE: another OATS question > > > Yes that will work too. I like the SNA or VNA because they calibrate out the > cable loss. As I understand it, one connects the RX and TX antenna cables > together and then performs a two-port cal. Then connect the cables to their > respective antennas and read S21 or S12 (should be the same either way). Then > only the AF needs to be factored in. > > If I understand the OATS cal procedure, the RX antenna height is moved from 1 > meter to 4 meters and readings are taken. Now this is the strange part: The > readings are averaged. Is this right? Now think about it- when a DUT is > tested, the RX antenna is moved until maximum signal is achieved- not the > average signal as the RX antenna height is swept. This method makes a DUT look > "hotter" than it really is and makes the site uncertainty appear larger. > > If the cal consisted on taking only the maximum signal, then the correct > height could be determined by simulations and the antenna could be swept close > to this height. Much less data to take. These antenna heights will of course > be different for horizontal and vertical polarization. > > Dave Cuthbert > Micron Technology > > -----Original Message----- > From: Luke Turnbull [mailto:[email protected]] > Sent: Monday, June 23, 2003 2:24 AM > To: [email protected]; [email protected]; drcuthbert > Subject: RE: another OATS question > > > Or a Spectrum analyser with tracking generator. > >>>> <[email protected]> 06/20/03 06:58pm >>> > Renting a VNA or SNA would really speed things up. > > Dave > -----Original Message----- > From: [email protected] [mailto:[email protected]] > Sent: Friday, June 20, 2003 10:02 AM > To: [email protected] > Subject: another OATS question > > > Hello everyone, > > I have worked with sites that used the hardware cloth (screen) over concrete > in the past. When the tears would happen, they would patch that area with > screen to cover the hole and maintain continuity. Can this patching create a > problem with site attenuation, if there are too many patches? I was planning > to build the site with concrete underneath the screen. > > Also, do you know of a way to do the site attenuation faster? In the past, I > have used tunable dipoles (takes forever) and also broadband antennas, which > is a little faster. Normally, I have done the site attenuation with the > signal generator about 10 feet behind the transmitting antenna. This means > that you have to go outside, change the frequency, go inside and make the > measurement, then back outside again. All I have to work with is a signal > generator and spectrum analyzer. Would it make a difference to have the > signal generator inside the building (this means that the output cable to the > antenna would be approx. 30 feet long.) I guess as long as this long cable > for the transmit antenna is counted in the "V direct" reading, it should be > ok? Making site measurements faster will help me evaluate my proposed site > location. > > Thanks for your input. > Tim Pierce > > > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
