An annular ring microstrip antenna (ARMSA) with metallic drilled holes and a defected ground structure is proposed for ultra-wideband applications. The annular ring microstrip patch antenna is excited by the microstrip line feed. The outer radius of the annular ring was optimized in this paper to choose the resonant frequency corresponding to the highest mode. The inner radius boosts the structure’s gain. A defected conductive strip with an arc in the center increases bandwidth at the lower end, increases gain and suppresses Co and Cross-pole isolation. Incorporating a metallic via array excites and includes several closely spaced lower order modes, increasing the fractional bandwidth to 108%. The gain of the proposed configuration is 10dBi at the resonance frequency. It offers Front to back lobe ratio (FBR) of 34dB and 97% radiation efficiency. The performance of the fabricated prototype agrees well with the simulated one.
