Omnidirectional dipole antenna with wideband and low gain variation

Abstract

This study presents an omnidirectional dipole antenna with wideband and low gain variation in the horizontal plane. The antenna is made up of two driven dipoles and two parasitic dipoles placed symmetrically on both sides of a central ground plane. The driven dipole is made up of two planar arms printed on both sides of the substrate. Two small slits on both sides of the driven dipole, a large centrally placed slit in the driven dipole, extensions on both sides of the driven dipole with different dimensions, and parasitic dipoles are introduced to greatly enhance the bandwidth and also attain a low gain variation. The fabricated antenna achieves a wide impedance bandwidth of 105.5% (1.36-4.4 GHz) for S 11 ≤ -10 dB, and an average gain of 4.14 dBi with a low gain variation of 2 dB. The antenna may find applications in 2G/3G/LTE frequency bands.