A Multiband Dual-Polarized Omnidirectional Antenna for Indoor Wireless Communication Systems

In this letter, a multiband dual-polarized omnidirectional antenna is studied. Two printed circular dipole arrays are employed for horizontal polarization (HP), while a simplified discone antenna is used for vertical polarization (VP). The two dipole arrays are fixed on the top and bottom of the VP element, respectively, and combined by a diplexer to make up the HP elements. The VP element is composed of three radiation patches with an external profile of a discone shape, which significantly lower the antenna's fabrication cost. To realize a compact structure, the HP element together with a circular patch works as the ground plane for the VP element. Simulated and measured results show that the frequency bands of 690 MHz-1.03 GHz and 1.69-3.21 GHz for HP and 770-980 MHz and 1.70-3.75 GHz for VP are achieved. Good port isolation, low cross-polarization level, and omnidirectional radiation patterns for both HP and VP in the azimuth plane are obtained over the whole working bands, which indicate that the proposed antenna can be widely used for indoor multiple-input-multiple-output (MIMO) communication systems.