Recently a defected ground structure (DGS) have been introduced,
DGS is realized by etching off a simple shape defected from the ground
plane, depending on the shape and dimensions of the defect, the
shielded current distribution in the ground plane is disturbed resulting
a controlled excitation and propagation of the electromagnetic waves
through the substrate layer. Defected ground structures, either in
a single configuration or periodic form that is frequently referred to
as a photonic band gap (PBG) show slow-wave effects leading to
considerable size realization. A geometry of a dumb-bell shaped DGS
etched on the ground plane between the two patch arrays elements.
The dimension of the DGS is optimized for the band gap at the
resonant frequency of the antenna by trial and error approach. The
Progress In Electromagnetics Research B, Vol. 4, 2008 29
square lattice dimension is (a×b), with etch gap distance g and width
of the gap w [11].