Application of D-Dot Sensor in HEMP Shielding Effectiveness Measurements

Shielding effectiveness (SE) measurements are essential for ensuring the electromagnetic isolation of electronic equipment inside a shielded shelter from external electromagnetic environments. IEEE-STD-299 defines the methodology for SE measurement. However, SE measurement becomes challenging when the shielded shelter is populated with electronic and electrical systems, as antenna placement becomes difficult.This experimental study investigates the suitability of a D-dot sensor for SE measurement in a shielded shelter designed to meet high-altitude electromagnetic pulse (HEMP) shielding specifications (80 dB) as per MIL-STD-188-125-1. The paper proposes the application of a single D-dot sensor (operating up to 1 GHz) for SE measurement, along with pre-amplifiers and power amplifiers, to assess the SE of a shelter. A Montena make ACD (asymptotic conical dipole) type free-field D-dot sensor (SFE1G) with an equivalent sensing area of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1 \times 10^{-2} \mathrm{m}^{2}$</tex> is utilized.The SE measurement is conducted on an anteroom of an EMC chamber with known SE values <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\geq 80 ~\text{dB}$</tex>, using both the D-dot sensor and conventional antennas (biconical and log-periodic). The SE measurement results obtained with the D-dot sensor are compared and validated against those from conventional antennas, indicating the feasibility of using the D-dot sensor for shielding measurements.