A Dual Band SIR Coupled Dipole Antenna for 2.4/5.2/5.8 GHz Applications

A novel physically small, coplanar, dual band antenna for 2.4-, 5.2-, and 5.8-GHz industrial, scientific and medical (ISM) band applications is proposed. The antenna element occupies an area of 25 mm × 9 mm on a substrate of thickness 1.6 mm and relative permittivity 4.3. The wide band at the higher resonance is due to the modified planar dipole and the lower resonance is achieved by a stepped impedance resonator (SIR), which is electrically coupled to the modified dipole. The 2:1 VSWR impedance bandwidth of the proposed antenna is 95 MHz for the first resonance and 1.38 GHz for the second resonance. The radiation patterns are nearly omnidirectional and the maximum measured gain is 2.6 and 3.6 dBi at 2.48 and 5.35 GHz, respectively.