ANSI C63.7-2015 pdf free download

ANSI C63.7-2015 pdf free download.American National Standard Guide for Construction of Test Sites for Performing Radiated Emission Measurements.
ANSI C63.5, American National Standard for Electromagnetic Compatibility—Radiated Emission Measurements in Electromagnetic Interference (EMI) Control—Calibration of Antennas (9 kHz to 40 GHz). ANSI C63.14, American National Standard Dictionary of Electromagnetic Compatibility (EMC) including Electromagnetic Environmental Effects (E3). CISPR 16-1-4 Edition 3.1 with Amendment 1:2011, Specification for Radio Disturbance and Immunity Measuring Apparatus and Methods—Part 1-4: Radio Disturbance and Immunity Measuring Apparatus— Antennas and Test Sites for Radiated Disturbance Measurements. Hemming, L. H., Electromagnetic Anechoic Chambers: A Fundamental Design and Specification Guide, Piscataway, NJ: IEEE Press, 2002. 3. Definitions For the purposes of this guide, refer also to the definitions provided in ANSI C63.14 and ANSI C63.4. alternative test site: A location commonly identified as follows:  Radio frequency (RF) absorber-lined metal test chambers with only the floor composed of a conductive material, generally referred to as a semi-anechoic chamber (SAC);  office or factory buildings large enough for reflections to not disrupt the field at the point of measurements;  weather-protected (covered) open-area test site (OATS), because of the potential effects of the cover material. NOTE—Metal-shielded enclosures and other sites that do not comply with the volumetric normalized site attenuation (NSA) requirements should be used only for exploratory radiated emission measurements; see 5.4.2 in ANSI C63.4- 2014. fully anechoic room (FAR): Shielded enclosure, the internal surfaces of which are lined with radio- frequency energy absorber material that absorbs electromagnetic energy in the frequency range of interest. normalized site attenuation (NSA): Site attenuation divided by the antenna factors of the radiating and receiving antennas (all in linear units).
4. General considerations Below 1 GHz, test sites such as OATSs, have a conductive ground plane with no significant reflective surfaces above that plane. At 1 GHz and above, test sites simulate near free-space conditions which significantly reduce the reflection off the conductive ground plane used at 1 GHz and below. Reflective surfaces above the ground plane can affect emission measurements below, at, and above 1 GHz. Such surfaces should either be a significant distance away from the measurement area, or treated with RF absorber material such as those used in a SAC or FAR to reduce unwanted reflections from the metal walls and ceiling (and floor in the case of a FAR) if not treated with absorbers. Recommended construction characteristics of the test site, the ground plane, instrumentation, EUT services and related information, are provided in Clauses 5, 6, 7, and 8. These recommendations should be followed so as to achieve adequate test sites, as established by performing site validation tests. These tests include the normalized site attenuation (NSA) measurement for 30 MHz to 1 GHz, as described in ANSI C63.4, and the S VSWR (site voltage standing wave ratio) measurements for 1 GHz to 18 GHz, as described in CISPR 16-1-4 (also referenced in ANSI C63.4). This guide describes construction techniques that can assist in meeting the site validation requirements. 5. Basic test site construction planning and guidance 5.1 General This clause presents construction considerations for OATSs and covered OATSs, semi-anechoic chambers, and fully anechoic rooms. While emissions measurements can also be performed in transverse electromagnetic (TEM) cells and reverberation chambers, those will not be addressed as the construction considerations are specific to the manufacturer’s design. In addition, it is assumed that any enclosed test facility such as a semi-anechoic chamber provides sufficient shielding in its design to not have the RF ambient outside the chamber affect emission measurements inside the chamber.
5.3 Semi-anechoic chamber (SAC) (30 MHz to 18 GHz) ANSI C63.4 allows the use of the SAC as an alternative test site. The SAC consists of a shielded enclosure with four walls and ceiling treated with RF absorber material and a conducting ground plane floor. Typically a combination of ferrite tile and pyramidal-shaped RF foam absorber is used to provide the required attenuation of reflections across the frequency range of use. Computer modeling of RF absorber is frequently used to determine the placement and effectiveness of the RF absorber. The following construction guidelines are relevant for SACs; see also Hemming 2002. 7 a) For 30 MHz to 1 GHz, the floor of the enclosure is a conductive surface which will act as the ground plane. The same chamber can be used above 1 GHz with appropriate changes applied to the floor of the enclosure. At 1 GHz and above, the conductive floor between antenna and EUT should to be treated with RF absorber of ample size and performance to reduce the reflection off the floor for simulating near free-space conditions. b) The enclosure should be sized adequately to meet the requirements for the measurement distance identified in specifications or regulations. The usual measurement distances are either 3 m or 10 m. The selection should depend on the requirements for the test, unless its use is only needed at one of these distances. At a minimum the floor dimension, taking into account the space taken up by the RF absorbers on the walls, should be no smaller than needed to accommodate the required ground plane dimensions (see 6.2.1.2). Again, modeling is often used to optimize the room size.