One important EMC compliance test is to determine whether external RF fields can affect your product. This test is also often referred to as radiated immunity or radiated susceptibility testing and is defined by the IEC 61000-4-3 standard for commercial products. For commercial products, the test is usually performed from 80 to 1,000 MHz at E-field levels from 3 to 20 V/m depending on the product environment or application. The test is performed in a shielded semi-anechoic chamber using a broadband antenna to transmit the RF in the direction of the product under test. The shielded chamber prevents interference to other communications services. Some military, vehicular, or aerospace applications require testing to 200 to 1,000 V/m and frequencies up to 18 GHz or more. The RF signal is generally modulated by a 1,000 Hz AM sine wave modulation set to 80% for commercial testing and either square wave or short-duration (at times less than 1%) pulsed modulation, typically at 1 kHz for military and aerospace testing. The modulation is designed to test for audio rectification issues (or radar pulse interference for military testing). For example, if the RF signal is rectified by semiconductor junctions or in audio or other analog circuitry, the low-frequency modulation could cause bias upsets or otherwise disrupt sensitive analog circuitry.

Chapter Contents:

• 6.1 Introduction to Radiated Susceptibility
• 6.2 Radiated Susceptibility Checklist
• 6.3 Typical Failure Modes
• 6.4 Troubleshooting at the Test Lab
• 6.5 Troubleshooting at Your Facility
• 6.6 Special Cases and Issues
• 6.7 DIY Tricks and Low-Cost Tools
• 6.8 Typical Fixes

Inspec keywords: anechoic chambers (electromagnetic); amplitude modulation; semiconductor junctions; electric admittance; electromagnetic shielding; conformance testing; interference suppression; antenna radiation patterns; IEC standards; radar interference; microwave antennas; radar antennas; broadband antennas; electromagnetic compatibility; aerospace testing; military radar

Other keywords: square wave; low-frequency modulation; EMC compliance test; radar pulse interference; communications services; frequency 18 GHz; AM sine wave modulation; frequency 1 kHz; audio rectification issues; military testing; analog circuitry; broadband antenna; shielded semi-anechoic chamber; IEC 61000-4-3 standard; RF transmission; aerospace testing; commercial products; external RF fields; short-duration pulsed modulation; radiated susceptibility testing; semiconductor junctions; radiated immunity; E-field levels; frequency 80 MHz to 1000 MHz; interference prevention

Subjects: Radar equipment, systems and applications; Modulation and coding methods; Radar and radiowave systems (military and defence); Aerospace testing and simulation; Electromagnetic compatibility and interference; Single antennas; Semiconductor junctions