This paper proposes a novel miniaturized rectangular loop antenna sensor consisting of a multiturn wire and a cuboid ferrite core. The lateral surface of the ferrite core is tightly wound by the multiturn wire. To verify its feasibility, the antenna sensor is fabricated, and the antenna factor (AF) levels are measured using the three-antenna method from the very low frequency (VLF) to the high-frequency (HF) bands. The measured AF levels are 31.8 dB (with a covering plastic case) and 33.1 dB (without a covering plastic case) at 30 kHz. In addition, the proposed antenna is employed in the shielding effectiveness measurement of a small commercial cabinet to observe its suitability for shielding effectiveness (SE) measurement of small shielding enclosures. The SE values averaged over the frequency range from 10 kHz to 3 MHz are 4.1 dB and 12 dB in the horizontal and vertical polarizations, respectively.

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.

This paper proposes an electrically small and frequency selective loop (FSL) antenna for shielding effectiveness (SE) measurement in low frequency (10 kHz-30 MHz) magnetic fields. The proposed antenna consists of an outer loop and an inner loop. A low-pass filter is placed between outer and inner loop to improve the antenna factor (AF) in the upper frequency band as the number of loop turns increases. The size of the designed antenna is 220 mm  220 mm, which achieves 46 % reduction of the antenna area compared to conventional 300 mm loop antennas and the proposed antenna preserves the AF characteristic over the entire frequency range (10 kHz-30 MHz). In addition, the loop of the designed antenna is printed using microstrip techniques, which reduces the cost and complexity of the antenna fabrication. The results demonstrate that the proposed antenna is suitable for SE measurements of small enclosures (all dimensions between 0.75 m and 2 m). INDEX TERMS Electrically small loop antenna, frequency selective antenna, SE measurement small enclosures