Observation of multiband characteristics of microstrip antenna using defected ground structure

Multiband antennas play a significant role in many wireless applications. A simple rectangular microstrip with defected ground structure is observed. As defected ground structures, single and double slot with several lengths in ground are modeled. The numerical simulation shows, the second resonance of the structure with single slots is shifted to lower frequency significantly if the slot length is longer, while the first resonance changes around 1 GHz. Whereas, for double slot case, the second resonance is shifted more, and there is a third resonance under 10 GHz, while the first resonance is practically unchanged. The measurements validated the numerical results.