The compact, broadband microstrip antenna with defective ground plane

A compact, broadband microstrip antenna with a defective ground plane has been successfully implemented. The impedance bandwidth of the proposed antenna could reach almost 256 MHz, which is about 4.3 times that (59 MHz) of the conventional microstrip antenna. With the presence of slots in parallel to non-radiating edges and a normal ground plane, the proposed antenna exhibits a dual-band operation while, with the presence of a defective ground plane and a normal patch, the impedance bandwidth of the fundamental mode is augmented and the resonant frequency is lowered simultaneously. A novel broadband technique exploiting a defective ground plane composed of 25 cross-shaped elements has been investigated experimentally, offering a new idea for bandwidth enhancement. Details of the antenna design and experimental results are presented and discussed.