An UWB horrizontally polarized omnidiectional antenna array with a series power divider

In this letter an ultra-wideband (UWB) horizontally polarized (HP) omnidirectional antenna array has been investigated. The proposed array consists of two elements, which are fed by an UWB 2-way series power divider with identical magnitude and reverse phase based on a coaxial cable. The designed antenna array operates at a frequency band about 81.25% (from 1.9 to 4.5 GHz with S11≤ -10 dB), and obtains very good gain variation in the horizontal plane, which is less than 0.5 dB over the relative frequency band about 67.83% (from 1.9 to 3.85 GHz), and increases to over 1 dB from 4.2 GHz. Meanwhile the gain is 0.2 - 2.75 dB in the impedance bandwidth. Within the operating frequency band, the cross polarization is less than -25 dB in the horizontal plane.