Low-Profile Magneto-Electric Dipole Antenna With Capacitively Loaded Loop and Stub-Added Notch

In this paper, a magnetoelectric dipole (MED) antenna with compact size, low profile, and wideband characteristics is proposed. The proposed antenna consists of an electric dipole, magnetic dipole, and reflector. The folded reflector and bent electric dipole form a capacitively loaded loop (CLL) structure. The CLL operates as a radiator at low frequencies, thereby significantly reducing the size of the antenna. Stub-added notches are incorporated into the electric dipole of the antenna. These structures improve the impedance-matching characteristics and thereby expand the bandwidth of the MED antenna. The proposed antenna is constructed entirely of metal without a dielectric substrate, resulting in high radiation efficiency. The electrical size of the proposed antenna is 0.316 λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> × 0.292 λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> × 0.0389 λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub>, where λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> denotes the wavelength at the lowest operating frequency. Furthermore, the –10-dB impedance bandwidth of the antenna is 0.71–1.96 GHz (93.6%), the gain within the operating bandwidth is 4.0–6.5 dBi, and the radiation efficiency exceeds 91%.