Harmonics reduction with defected ground structure for a microstrip patch antenna

A microstrip patch antenna using a defected ground structure (DGS) to suppress higher order harmonics is presented. An H-shaped defect on the ground plane with only one or more unit lattices has been utilized and yielded bandstop characteristics. Compared with a conventional microstrip patch antenna without the DGS unit cell, the radiated power of the DGS patch antenna at harmonic frequencies has been drastically decreased.