Design of a dual-band microstrip antenna using slotted annular-ring and concentric disk

A dual-band microstrip antenna using an annular ring and a concentric circular disk is proposed. The ring is designed and operated in the TM₁₂ mode which is a first band with its frequency of f_lr, the disk is operated in the TM₁₁ mode which is a second band with its frequency of f_hr. Two rectangular slots are used to achieve better bandwidth. Design examples of the dual-band antenna working at frequency of f_lr = 2.45 GHz and f_hr = 5.3 GHz are fabricated. The comparisons of simulated and measured results show good agreements.