A triple-band microstrip fed monopole antenna using defected ground structure for WLAN and Wi-MAX applications

A compact triple-band monopole antenna with dimension 30 × 40× 1.6 mm3 fed by a 50 Ω microstrip line is proposed in this paper. The signaling plane consists of a microstrip feed line and a radiating element. The radiating element contains two branches and two stubs. The branches of the radiating element are used to make the circuit to radiate at 2.3 GHz and 3.9 GHz. The stubs help in making the circuit to radiate at 5.3 GHz. Thus the proposed antenna is capable of radiating triple band of frequencies which meets the specifications of WLAN 2.4/5.3 GHz and Wi-MAX 3.9 GHz. The VSWR values are 1.2, 1.9 and 1.1 at 2.3 GHz, 3.9 GHz and 5.3 GHz respectively. The simulated return loss values at the desired frequencies are -19 dB at 2.3 GHz, -25 dB at 3.9 GHz and -38 dB at 5.3 GHz. The ground plane is designed with a defected ground structure with two inverted L shaped strips that helps to enhance the bandwidth of the system. The bandwidth of the proposed triple band antenna are (2.2 - 2.4) GHz, (3.7 - 3.92) GHz and (5.2 - 5.4) GHz. The radiation pattern of the proposed antenna is bi-directional in H-plane and unidirectional in E-plane which is suitable for WLAN and Wi-MAX applications.