Enhanced performances of a compact conical-pattern annular-ring patch antenna using a slotted ground plane

By embedding four radial slots in ground plane, enhanced performances of a probe-fed annular-ring patch antenna operated at the TM₂₁ mode for conical-pattem radiation have been obtained. The size reduction achieved for the proposed antenna is about 75%, compared with the corresponding conventional annular-ring patch antenna at a fixed operating frequency. Moreover, with the large lowering in the resonant frequency, the impedance bandwidth of the proposed antenna can greatly be increased by a factor of about 4.8. Also, the antenna gain measured is increased by about 3 dBi. Owing to these enhanced performances, the proposed antenna is suitable for present-day mobile communication. In addition, the design of adding a reflecting plate behind the antenna´s ground plane to reduce the backward radiation due to the embedded slots in the ground plane is also studied