ANSI SCTE 48-3-2018 pdf free download – Test Procedure for Measuring Shielding Effectiveness of Coaxial Cable and Connectors Using the GTEM Cell.
This document details the procedure for measuring the Shielding Effectiveness (S.E.) of coaxial cable and connectors using the Gigahertz Transverse ElectroMagnetic (GTEM) cell. More particularly, this procedure applies to measuring the S.E. of 75 Ohm braided coaxial drop cables and connectors presently used within the broadband communications industry. S.E. measurements can be performed with or without the affixing coaxial connectors removed from the measurement.
1.3. Benefits This procedure exists in order to provide a standard method of testing between laboratories performing Shielding Effectiveness tests. When utilized this procedure helps to ensure confidence in results when published.
1.4. Areas for Further Investigation or to be Added in Future Versions Future revisions of this document may build upon the work started here by increasing the understanding of:
• Variability of data between GTEM Cell systems with varied “uniform field” sizes.
• The affects of location differences between bare wire and shielded samples within the GTEM cell.
2. Normative References
The following documents contain provisions, which, through reference in this text, constitute provisions of this document. At the time of Subcommittee approval, the editions indicated were valid. All documents are subject to revision; and while parties to any agreement based on this document are encouraged to investigate the possibility of applying the most recent editions of the documents listed below, they are reminded that newer editions of those documents might not be compatible with the referenced version.
2.1. SCTE References
• No SCTE references are applicable.
2.2. Standards from Other Organizations
• No normative references are applicable.
2.3. Published Materials
• No normative references are applicable.
3. Informative References
The following documents might provide valuable information to the reader but are not required when complying with this document.
3.1. SCTE References
• No informative references are applicable.
3.2. Standards from Other Organizations
• IEC 61000-4-20 2nd Edition, August 1, 2010. Electromagnetic compatibility (EMC) – Part 4-20: Testing and measurement techniques – Emission and immunity testing in transverse electromagnetic (TEM) waveguides.
3.3. Published Materials
• A GTEM BEST PRACTICE GUIDE – APPLYING IEC 61000-4-20, TO THE USE OF GTEM CELLS. A. Nothofer, M.J. Alexander, National Physical Laboratory, Teddington, UK, D. Bozec,D. Welsh, L. Dawson, L. McCormack, A.C. Marvin, University of York, Heslington,UK(Principal contact: nothofer@ieee.org)
• http://ieeexplore.ieee.org/search/searchresult.jsp?newsearch=true&queryText=GTEM Multiple helpful documents
6.3. Calibration and Equipment Preparation Data points
– The number of measurement samples taken is at the discretion of the Engineer performing the test, however, as a minimum requirement there will be at least one sample point every 5 MHz (i.e. 5, 10, 15, …… upper frequency limit). When testing frequencies above 1GHz, it may be necessary to use multiple amplifiers to cover the entire range. The following items should be considered when using multiple amplifiers.
• Safety consideration must be taken into account if manually switching between amplifiers, and the amplifier outputs must be off before switching them.
• When using data collecting and control software for a spectrum analyzer, and manually switching amplifiers there should be a pause feature to stop the sweep at the correct frequency to switch amps and then continue sweep once correct amp is in place.
• Be sure to verify that all supporting equipment, i.e. pre amp, attenuators etc. are correctly chosen to cover the entire frequency range in question. RF power level – As this test is designed as a comparison of shielded vs unshielded cable, an exact field strength is not stated. It is necessary however to have enough energy in the GTEM as is necessary to achieve sufficient dynamic range for the measurements being made. Attenuator characterization – Any attenuators that may be inserted or removed from the measurement during the measurement process shall be characterized and data stored for later use during S.E. calculations.ANSI SCTE 48-3 pdf download.