  This paper presents a pixelated cubic antenna design with enhanced isolation
and diverse radiation pattern for vehicular applications. The design consists
of four radiating patches to take advantage of a nearly omnidirectional
radiation pattern with enhanced isolation and high gain. The antenna system
with four patches has been pixelated and optimized simultaneously to achieve
desired performance and high isolation at 5.4 GHz band. The antenna achieved
measured isolation of more than -34 dB between antenna elements. The overall
isolation improvement obtained by the antenna is about 18 dB compared to a
configuration using standard patch antennas. Moreover, isolation improvement is
achieved through patch pixelization without additional resonators or elements.
The antenna achieved up to 6.9 dB realized gain in each direction.
Additionally, the cubic antenna system is equipped with an E-shaped GPS antenna
to facilitate connectivity with GPS satellite. Finally, the antenna performance
has been investigated using a simulation model of the vehicle roof and roof
rack. The reflection coefficient, isolation and radiation patterns of the
antenna remains unaffected. The antenna prototype has been fabricated on Rogers
substrate and measured to verify the simulation results. The measured results
correlate well with the simulation results. The proposed antenna features
low-profile, simple design for ease of manufacture, good radiation
characteristics with multidirectional property and high isolation, which are
well-suited to vehicular applications in different environments.
