RFI Testing Service for R&D

Introduction Originally used for comparative testing of security products, this automated test facility using a large GTEM test cell was developed and used by Cranage engineers to assist in developing PIR movement detectors with immunity exceeding 50V/m. The testing system accurately plots the equipment under test (EUT) immunity threshold (V/m) against frequency for keyed carrier, pulsed and amplitude modulated carrier waves. Field strength measurements are made using a 3-axis E- field probe calibrated by National Physics Laboratory. Technical Data Frequency range: 20Hz to 4GHz Test level: up to 100V/m Test methods: keyed carrier, pulsed, or sinusoidal AM Max. EUT size: 430 (h) x 530 (w) x 530 (d) mm How it Works Cranage test equipment are controlled via IEEE488 bus using Lotus Measure software. Frequency range, frequency increment, test level and EUT recovery time are set according to the test requirements. A bus controlled DMM is used to monitor the EUT via a suitable interface, e.g. relay contact. The EUT is continually monitored during the test process, a maloperation or deviation being recorded by the measurement control system when the monitored voltage exceeds a pre-set trigger level defined by the operator. Test Set-up The EUT is placed in the GTEM test cell above the ground reference plane in a test fixture manufactured from low permittivity dielectric. This is placed within a uniform E-field below the septum with supply, control, and monitoring cables leading out at the ground reference plane. Ferrite decoupling is applied at the ground reference plane to prevent RF currents affecting external instrumentation. Cable disposition is noted and if necessary a second test fixture used to provide a stable reference.

For more information on RFI Testing Service for R&D talk to Cranage EMC & Safety