Impedance Extraction using Impedance Perturbation Method of Electrically Small HF Loop Antenna with Undercover Ferrite Sheet

Electrically small high frequency (HF) loop antenna with undercover ferrite sheet yields high radiation resistance for multi-turn structure. Antenna impedance without radiation differs greatly from that with the radiation effect. Impedance perturbation method is used for extracting antenna impedance with radiation effect at a desired frequency. Matching networks are designed based on the extracted antenna impedance. The measurement results show that the antenna with the designed matching network provides higher return loss.