ANSI C63.4A:2017 pdf free download – American National Standard for Methods of Measurement of Radio- Noise Emissions from Low-Voltage Electrical and Electronic Equipment in the Range of 9 kHz to 40 GHz
Two antennas are set up on the test site in a specific geometry as illustrated in Figure D.1 and Figure D.2 (see D.8); Figure D.2 is an illustration for dipoles only–the actual geometry requirements are in D.2.3. The NSA procedure requires two different measurements of the voltage received V R . The first reading of V R is with the two coaxial cables, including any added impedance matching attenuators whose insertion losses are not included with the antenna factors (if used), disconnected from the two antennas and connected to each other via an adapter. The second reading of V R is taken with the coaxial cables, including any added impedance matching attenuators (if used), reconnected to their respective antennas and the maximum signal measured with the receive antenna scanned in height (Heirman [B20]). For both of these measurements, the signal generator voltage level V I is kept constant. The first reading of V R is called V Direct and the second reading is called V Site . These voltages are used in Equation (D.1) or Equation (D.2) to calculate the measured NSA (AN ):
The parameters AF T and AF R in Equation (D.1) and Equation (D.2) are determined using the applicable antenna calibration process as specified in ANSI C63.5. For Equation (D.1), the mutual impedance correction factor ∆AF TOT (see Table D.9 in D.8) applies only to the site geometry of 3 m separation, for both horizontal and vertical polarizations, when using tuned dipoles. The mutual impedance correction factor ∆AF TOT = 0 for all other geometries using tuned dipoles. For Equation (D.2), the appropriate GSCF values, as determined per ANSI C63.5, shall be used; see also the considerations in NOTE 2 about use of Annex G and Annex I of ANSI C63.5-2017. NOTE 1—Users are cautioned that the determination of the appropriate GSCF values using the methods described in ANSI C63.5 is a complex undertaking, and that these factors are dependent on the exact type of antenna used. NOTE 2—The theoretical values for GSCF in Annex G of ANSI C63.5-2017 apply only for biconical antennas that comply with the dimensional and other conditions stated within that annex. If such biconical antennas are used for performing NSA measurements at heights that are not covered in that Annex G (e.g., 2.5 m for vertical, and 3 m for horizontal), appropriate GSCF values are determined using the procedure in Annex I of ANSI C63.5-2017. For biconical antennas that differ from the dimensional and other conditions stated in Annex G of ANSI C63.5-2017, and for LPDA antennas and/or hybrid antennas, GSCF values are determined using the procedure in Annex I of ANSI C63.5-2017. Linearly-polarized antennas, with calibrated antenna factors, are required for NSA measurements. Antenna factors shall be calibrated using the Standard Site Method (SSM) specified in ANSI C63.5, and the measurements involved shall be traceable to a national standard. Antennas shall be calibrated as a pair (i.e., transmit antenna and receive antenna shall be calibrated together), in accordance with 4.4.2 of ANSI C63.5-2017. Antenna factors usually account for losses in the balun.