A Compact Magnetic–Electric CP Element and Its Design in Pattern Reconfigurable Antenna With Full Coverage in Azimuth Plane and Wide Coverage in Elevation Plane

A compact magnetic-electric circularly polarized (MECP) element is proposed and employed in the design of a pattern reconfigurable antenna that provides full coverage in the azimuth plane and wide coverage in the elevation plane. The MECP element, working in the zeroth-order resonant (ZOR) mode, inherently has a compact size of 0.17λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.32λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.06λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> denotes the free space wavelength at 920 MHz). The MECP element achieves a fan beam with wide azimuthal and elevational 3-dB axial ratio (AR) beamwidths of 192° and 110°, respectively. By integrating four such sequentially rotated MECP elements, a pattern reconfigurable antenna is designed and fabricated. The antenna has the advantage of compact size of 0.58λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.58λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.04λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub>. By switching the excited elements through the feeding ports, the antenna provides four reconfigurable beams for full coverage in the azimuth plane (one effective beamwidth covering an angle larger than 90) and wide coverage in the elevation plane (effective beamwidths covering angles within the range of  ≤ 75).