Whitepaper
EMC Antenna Fundamentals
This paper provides a fundamental overview of antenna selection and terminology relevant to Electromagnetic Compatibility (EMC) testing. It distinguishes between radiating devices like antennas and non-radiating field generators such as TEM cells, highlighting that EMC applications primarily utilize antennas for radiated emissions, immunity, site qualification, or reverberation chamber excitation. The article details concepts like directivity (2.14 dBi for a half-wave dipole compared to an isotropic source), gain (often including mismatch factor in practical EMC use), and crucial antenna characteristics such as VSWR, return loss (e.g., 9.5dB for VSWR=2:1) and antenna factor – relating incident electric field to load voltage. Finally, it outlines the function and benefits/drawbacks of various antenna types commonly used in EMC testing including loop antennas (20Hz-30MHz), rod antennas (30Hz-50 MHz), dipoles, biconical antennas (20MHz–300MHz) and their relevance to standards like MIL-STD 461 and ANSI C63.5.