Suppressing up to fourth harmonic of an ISM band microstrip patch antenna using compact defected ground structures

Defected ground structure (DGS) consisting of 2 I‐shaped etched‐out patterns underneath a microstrip line with an inverted L‐shaped stub is proposed to suppress all higher harmonics up to fourth harmonic of an inset cut microstrip patch antenna. The overall size of the proposed DGS and the position of the stub are optimized to achieve wide stop‐band characteristics. All the higher order harmonics are investigated and suppressed successfully by utilizing the proposed compact DGS of area 24%–96% smaller than that published in other related articles. The overall length of the proposed DGS is successfully formulated and verified at the desired resonating frequency of the stop‐band. The antenna is designed for ISM band (2.41–2.46 GHz) applications. An equivalent circuit of the proposed DGS is also modeled and the same is verified using ADS 2009. The simulated results are validated experimentally and good mutual agreements between the simulated and experimental results are observed.