Ken, A while back the ANSI C63.5 standard went to a 10 Meter separation distance with a 2 Meter transmit height in the Horizontal Polarity (quasi-free space) even though they are calibrated over a very large ground plane (there is a minimum size and flatness requirement in the standard(s).
The Transmit antenna is at the 2-meter fixed height and the receive antenna is swept from 4 to 1 meter. Those factors are used at 3- or 10-meter distance in both polarities (horizontal and vertical). Most of the labs are using bilog (combination biconical and log periodic antennas from 30 to 1000 MHz at this point). Although some labs are using dual mast configurations with a bicon and log periodic antenna at 10 meters in claims that speeds up the testing however only in the oversized 10m chambers where site calibration allows that to be achieved. Personally, in the past I still have had our measurement antennas calibrated at 3 and 10 meters as the factors are different due to mutual coupling. Note, I am talking about antennas used for measurement not for the calibration of OATS or chambers. Calibration antennas (Bicons and Logs) get done at both 3 and 10 meters in both the horizontal and vertical polarities and mutual coupling factors are used for the bicons as part of the validation process of the sites. Larry K. Stillings Compliance Worldwide, Inc. Test Locally, Sell Globally and Launch Your Products Around the World! FCC - Wireless - Telecom - CE Marking - International Approvals - Product Safety 357 Main Street Sandown, NH 03873 (603) 887 3903 Fax 887 6445 complianceworldwide.com<https://complianceworldwide.com/> Follow us on social media [cid:[email protected]] linkedin.com/company/compliance-worldwide-inc [cid:[email protected]] x.com/complianceww<twitter.com/complianceww> Privileged/Confidential Information may be contained in this message. If you are not the addressee indicated in this message (or responsible for delivery of the message to such person), you may not copy or deliver this message to anyone. In such case, you should destroy this message and kindly notify the sender by reply email. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of my firm shall be understood as neither given nor endorsed by it. From: Ken Javor <[email protected]> Sent: Tuesday, June 30, 2026 2:25 PM To: [email protected] Subject: [PSES] ANSI C63.4 / CIS{R 16-X query To those of you who perform radiated emission qualifications to subject standards on either open area test sites, semi- or fully anechoic chambers: By way of background, my direct experience and any future activity with RE measurements is vehicle-specific EMI requirements, such as MIL-STD-461, RTCA/DO-160, and CISPR 25, which are all made at one-meter separation. I don’t have a current version of subject standards, and am not interested in acquiring them ($$$). With respect to subject standards, what antenna factors are used today? At one time, there were distance-specific antenna factors, such as 3, 10 or 30 meter antenna factors. Is it just far field antenna factors today? Similarly, are separate polarization-specific (vertical and horizontal) antenna factors used, or is just a single antenna factor, no matter how determined in CISPR 16-1-6, or ANSI C63.5? Finally, how is the height-dependent nature of antenna factors treated? On a 1 - 4 meter height sweep, the antenna factor for wire-type antennas is not constant. My reading of CISPR 16-1-6 says it is a far-field factor, with height dependence covered under the uncertainty assigned to the measurement. Is that the case, or is the height of the antenna somehow recorded and a height-specific antenna factor applied? The latter doesn’t make sense to me, but it is my understanding of what one engineer told me. Thanks in advance, Ken Javor Ph. 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