A Dual-mode Miniaturized Rhombus-Shaped Antenna Inspired with CRLH-TL Employing Christmas-Tree Shaped Meander Line

In this paper a rhombus-shaped monopole antenna loaded with Christmas tree-shaped meandered line is proposed. This antenna offers dual-band characteristics with electrical size of
$0.235\lambda_{0}\times 0.235\lambda_{0}\times 0.013\lambda_{0}$
corresponding to lowest resonant frequency of 2.62 GHz. The suggested antenna consists of slotted rhombus-shaped patch on top layer and partial ground plane on bottom layer. Further, the meandered lines are used to increase the current travelling path and connected to the partial ground plane. The Christmas tree shape is chosen to accommodate the meandered lines within the area available on the bottom side of the antenna. It is implemented on a
$27\times 27\times 1.6\ \text{mm}^{3}$
FR4 Glass Epoxy substrate having permittivity of
$4.4+\mathrm{j}0.088$
. Simulated results show that the antenna is capable to work over 2.52-2.73 GHz and 3.75-3.86 GHz. Moreover, It is observed that the measured results are following the simulated results with fractional bandwidth of 7.66% and 2.42% at center frequencies of 2.61 GHz and 3.71 GHz, respectively. This antenna provides consistent dipolar pattern in the
$xz$
plane while proper omni-directional pattern in the
$yz$
plane at both the bands. Excellent cross polarization level of greater than −22.5 dB ensures that antenna will not radiate in the undesired direction.