A Novel Omni-directional Antenna with Low Gain Variations for WiFi Communications

An omni-directional monopole antenna with low gain variations is presented for Wireless Fidelity (WiFi) communications in this paper. Compared with the conventional microstrip antenna, the novel patch antenna with simple structure shows good performance in the aspects of high gain and low gain variations. Within ±1dB gain variations, dual bandwidths of 2.41GHz-2.57 GHz (6.4%) and 2.87 GHz-3.77 GHz (27.1%) are achieved for WIFI communication systems. To acquire the dual-band and omni-directional characteristics, the rectangular patch etched with an annular-ring slot is employed. Owing to the coplanar waveguide (CPW) feeding structure, the proposed antenna has an excellent performance of a stable gain of 2±0.5 dBi.