A Partial-Annular Directional Antenna with Simple Structure for Limited Space

A partial-annular directional antenna with wide bandwidth and high gain is proposed in this paper. The radiator is a simple partial-annular metal microstrip loaded with hexagonal patch, which is exited with coaxial cable. The ground is reduced to a rectangular patch with small area, which is required by the deployment. As the reflector, the circular Aluminum plate is λ/10 below the radiator to enhance the antenna gain and front-to-back ratio (FBR). The air gap between the semi-annular antenna and the reflector is also helpful for the improvement of impedance math. The simulation results show that the relative bandwidth of the proposed antenna is 46.6% (3.85 – 6.19 GHz), and the gain varies from 7.91 to 9.93 dBi. Due to the semi-annular strip structure and defected ground, the proposed antenna could be used for the limited deployment space, such as radio wave detection, terminal of mobile communication, and so on.