Design of a Miniaturized Printed Multi-Turn Loop Antenna for Shielding Effectiveness Measurement

This paper proposes a novel miniaturized loop antenna consisting of a multi-turn printed strip and a ring-shaped ferrite core. The lateral surface of the ferrite core is tightly wrapped by the circular multi-turn strip, which is printed on a thin, ring-shaped Styrofoam. To verify the feasibility, the proposed antenna is fabricated, and the antenna factor (AF) levels are measured using the three-antenna method from the VLF to HF band. The AF levels by measurement, theory, and simulation are 36.14 dB, 34.01 dB, and 33.6 dB at 30 kHz, respectively. In the VLF band, the antenna has a diameter of 114 mm, which is miniaturized to less than 60% compared to previous research. In addition, the proposed antenna is employed in the shielding effectiveness (SE) measurement of a small commercial cabinet to observe its suitability for SE measurement of small shielding enclosures. The SE values averaged over the frequency range from 10 kHz to 3 MHz are 5.19 dB and 14.14 dB in the horizontal and vertical polarizations.