Bandwidth enhancement design of single-layer slotted circular microstrip antennas

By loading properly arranged slots in a single-layer circular microstrip antenna, the novel bandwidth enhancement design is proposed and experimentally studied by using a single probe feed. For the proposed broadband design, a pair of narrow arc-shaped slots is close to the side edges of the circular patch and connected with a narrow rectangular slot oriented along the excited surface current direction of the fundamental resonant mode of the unslotted circular patch. By properly adjusting the narrow rectangular slot's length, broadband operation of the proposed circular microstrip antenna near its fundamental resonant mode can be achieved. And, it is found that the obtained impedance bandwidth in the proposed design can be greater than 2.3 times that of a conventional unslotted circular microstrip antenna. Details of the proposed antenna designs are described, and typical experimental results are presented and discussed.