A Dual-Polarized Dual-Band Antenna With Omni-Directional Radiation Patterns

A new dual-polarized dual-band (DPDB) omni-directional antenna is presented in this communication. The proposed antenna consists of a circular patch with eight open slots, eight shorted metal pins, and a central feed coaxial probe. By utilizing TM
₀₁
mode, eight shorted metal pins, and open slots can radiate
$\theta$
- and
$\varphi$
-components, respectively. Omni-directional circular polarization can be generated over the lower band. When the basic TM
₀₂
mode is excited, omni-directional linear polarization can be generated over the higher band. Omni-directional circularly polarized fields and omni-directional linearly polarized fields can be achieved at both resonant frequencies. The circular patch antenna is printed on a substrate with a radius of 48 mm (
$0.24~\lambda _{\mathrm {\mathbf {0}}}$
, where
$\lambda _{\mathrm {\mathbf {0}}}$
is the wavelength in free space). The antenna has a low profile of 4 mm (
$0.02~\lambda _{\mathrm {\mathbf {0}}}$
). The antenna is fabricated and measured; the measured results show that the impedance bandwidths for VSWR <2 are 18 MHz (1566—1584 MHz) and 32 MHz (2440—2472 MHz). The axial ratio in the xoy plane is less than 3 dB over the lower band. These measured results are congruent with the simulated data. The antenna can be a good candidate for both GPS and WLAN applications. Besides, the S-parameters, radiation patterns, and some key structures are studied.