A Double Layer Interdigital CPW Metamaterial Director for LTE Antenna System

This paper proposes the design of metamaterial director for antenna, which has the feature of double layer based on CPW structure by using interdigital CPW technique. The designed unit cell of metamaterial director has resonance frequency of 1.8 GHz, covering the frequency band of LTE system (1.72 GHz-1.83GHz). By using this technique, the unit cell can have negative permeability, the required property in design at the resonance frequency. It is found that size of the designed interdigital CPW unit cell has been reduced to
$\lambda/8$
. The result causes from the slow wave effect on transmission line in the structure, which electrical and physical lengths of transmission line are not equal from that effect. The unit cell size of 14 mm was designed and used to form a
$7\times 7$
array as a result of metamaterial director with overall size of 98 mm. The 1.8 GHz dipole antenna was then used with the metamaterial director. The results show that the simulation impedance matching result less than −10 dB with the bandwidth of 183 MHz. Using the designed director, the antenna gain has been increased from 2 dB to 5.91 dB with directional radiation pattern. The proposed metamaterial director is appropriate for modern wireless communication systems.