An Omnidirectional Triple-Band Circular Patch Antenna Based on Open Elliptical-Ring Slots and the Shorting Vias
A circular patch antenna based on open elliptical-ring slots and shorting vias with conical radiation patterns is proposed. Fed by the coaxial probe at the center of the circular patch, the proposed antenna is excited at three resonant modes simultaneously. The first resonant mode (monopolar patch mode) is achieved by six shorting vias, each of which is placed at the center of the open elliptical-ring slot. By embedding six open elliptical-ring slots on the patch, the other two resonant modes of the open elliptical-ring slot resonator, TE110 and TE210, can also be excited. Due to symmetrical slots on the patch, these two modes can produce conical patterns, and their frequency ratio can also be tuned by adjusting the size of the slots. The proposed antenna is fabricated and measured. The measured results show that the proposed antenna can provide three operating bands which meet the required bandwidth specifications of 2.4/5.8 GHz WLAN and 3.5/5.5 GHz WiMAX standards. Detailed design considerations of the proposed antenna are described, and both the simulated and measured results are given. Moreover, the effects of the vital parameters on the performance of the proposed antenna are analyzed in this paper.