Low-profile wideband circularly polarized asymmetric dipole antenna with artificial magnetic conductor

In this article, a novel low-profile asymmetric dipole antenna with artificial magnetic conductor (AMC) is presented for wideband circularly polarized operation. First, the asymmetric dipole is adopted to realize a wide impedance bandwidth. By modifying the shape of dipole arms and combing a rhombus-shaped arm with a quasi-triangle-shaped arm, three resonances are achieved by the asymmetric dipole, leading to a wide impedance bandwidth. Second, an AMC surface with square patch units is introduced to reduce the antenna profile to 0.11 lambda(0), where lambda(0) denotes the lowest operation wavelength in free space. Finally, the presented wideband circularly polarized (CP) antenna design was fabricated and tested. Reasonable agreement between the measurements and simulations is obtained, demonstrating that this CP antenna achieves a 115% impedance bandwidth (1.45-5.4GHz) and a 97% axial ratio bandwidth (1.69-4.88GHz). Within the CP operation band, the presented antenna yields symmetrical and unidirectional radiation patterns with a 6.7-dBic average gain. Such a broadband and low-profile CP asymmetric dipole antenna can be a promising candidate for a wide variety of CP wireless applications.