Mechanically Reconfigurable Magnetoelectric Dipole Antenna with Tunable Bandwidth via Folding of the Electric Dipole

초록

In this paper, a magnetoelectric (ME) dipole antenna with mechanically tunable impedance bandwidth is presented using a bias-free and structurally simple folding-based reconfiguration of the electric dipole. The electric dipole is implemented using a kirigami-inspired folding structure composed of copper tape on a 0.125-mm-thick polyethylene terephthalate (PET) film. This structure enables continuous variation of the effective electrical length without modifying the feeding network or the quarter-wavelength shorted patch. By mechanically folding the electric dipole, its length can be adjusted from 26 to 35 mm, which alters the relative resonance behavior between the electric and magnetic dipole modes of the ME structure. Consequently, the impedance bandwidth is tuned rather than simply shifting the operating frequency. A prototype designed for the 2.4 GHz band was fabricated and experimentally evaluated. The results show that the lower resonance shifts from 2.22 to 1.82 GHz, resulting in a tunable impedance bandwidth of 1.6 – 2.8 GHz and a fractional bandwidth ranging from 43.7% to 54.6%. Throughout the tuning range, the antenna maintains stable unidirectional radiation characteristics, consistent gain. The proposed folding-based approach offers a simple and practical method for achieving bandwidth-tunable ME dipole antennas without the need for electrical switching or biasing networks.

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