An Electrically Small Frequency Selective Loop Antenna for Shielding Effectiveness Measurement

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).