A Dual-Polarized Omnidirectional Antenna With Small Plane Size for Indoor Distribution Applications

A dual-polarized omnidirectional antenna for indoor distribution with small plane size and low deviation from omnidirectionality (DFO) is presented. This antenna consists of a vertical-polarized (VP) element and a horizontal-polarized (HP) element. The VP element consists of two orthogonal pieces and a top-loaded disk, whereas the HP element is composed of two dipoles, a feeding network and a dielectric resonator (DR). The DR is introduced to reduce the plane size of the antenna; meanwhile, low DFO of the HP element can also be obtained. The overall size of the proposed antenna is 0.36
λ
_min
× 0.36
λ
_min
× 0.26
λ
_min
(with
λ
_min
being the wavelength of the lowest frequency). The measured results show an overlapped bandwidth of 35% (0.71–0.99 GHz) (|
S
₁₁
| < −10 dB) with DFO less than 1.6 dB for the VP element and 1.85 dB for the HP element. In addition, the cross-polarization levels in azimuth plane are lower than −20 dB for two elements.