Design of a probe excited circular ring above the reflector for bridging outdoor wireless LAN applications

Point to point communications have received attention for several decades. An antenna that can be useful for point to point communication is the antenna radiating a unidirectional beam pattern. This paper proposes to accomplish a unidirectional beam by using a probe excited circular ring above the reflector. The structure is simple and easy to fabricate. In addition, since there is no dielectric component, it has low loss. The antenna can be made using low cost material that is easy to find in the market. This structure is expected to be cost effective (S. Kusulvu et al, IEICE Trans Electron. vol. E84-C, no.4, pp. 443-450, 2001). The antenna design is straightforward. The ring radius is first specified to accomplish the condition of dominant mode propagation. The ring length is designed based on the suitable ring radius and desired directivity. Furthermore, the spacing between the probe excited circular ring and the reflector is selected to achieve compact antenna size. The antenna radiation patterns with and without the reflector are shown. The experimental results for the radiation pattern and impedance characteristic show that this antenna can be used for bridging outdoor wireless LAN systems.