ISO 11452-11:2010 pdf free download – Road vehicles – Component test methods for electrical disturbances from narrowband radiated electromagnetic energy一 Part 11: Reverberation chamber.
B.2 Measurement procedure
Before starting the measurements for the chamber characterization, clear the working volume (i.e. remove test bench).
For each of the probe locations, of which there are at least eight, and each of the characterization frequencies, perform the measurement procedure described below.
— Place the isotropic E-field probe at the location on the perimeter of the chamber working volume as shown in Figure B.1.
— Place the receiving antenna at the corresponding receiving antenna location within the chamber working volume. See Clause B.1 for restrictions of receiving antenna locations.
Adjust the RF source to inject an appropriate forward power Fo into the transmitting antenna such that the received power Rec is large enough (see below). Make sure that the frequency is in band for both transmitting and receiving antennas that are used. Care shall be taken to ensure that the harmonics of the RF input to the chamber are at least 15 dB below the fundamental. Set the amplitude measurement instrument to monitor the receiving antenna on the correct frequency.
— Step the tuner through 3600 in discrete steps so that the power measurement instruments and isotropic E-field probe capture the minimum number of samples as outlined in Table B.1 over one complete tuner rotation. Care shall be taken to ensure that the dwell time is sufficiently long enough that the amplitude measurement instrumentation and isotropic E-field probe have time to respond properly.
For each tuner position, record the received power from the receiving antenna, the field strength for each axis of the E-field probe (i.e. E, and Ez) and the forward power Fo into the transmitting antenna.
From these values compute the maximum received power, 1Rec, max’ average received power, Rec,avg’ the maximum field strength for each axis of the E-field probe (Exmax, Eymax, Ezmax) and the average forward power, over the tuner rotation. All calculations shall be done using linear units [i.e. W and V/m, not dBm or dB(pVim)]. Ensure that the noise floor of the power measuring instrument for the received power is at least a factor of 100 (i.e. 20dB) below the maximum received power, Rec max for proper average data collection. If this is not the case, increase the forward power appropriately or modify instrumentation. Large variations in forward power (i.e. 3 dB or more) are an indication of poor source/amplifier performance.
— Normalize each of the maximum isotropic E-field measurements (i.e. each of the three rectangular components) to the square-root of the average forward power (I is the index for the probe position).