Frequency-Reconfigurable Slot Antenna Enabled by Thin Anisotropic Double Layer Metasurfaces

A frequency-reconfigurable slot antenna using metasurface (MS) is proposed. Two identical anisotropic MS layers are loaded on top of a slot to achieve the frequency reconfigurability. The MS layer is composed of a periodic arrangement of I-shaped metallic inclusions placed in both the horizontal and vertical directions. The MS layers are fed by a linearly polarized slot antenna. The operating frequency of the proposed antenna is tuned by physically rotating the two MS layers with respect to the centre of the slot antenna. Rotation of the MS layers changes the effective permittivity and the loading on the slot antenna and hence the operating frequency changes. The proposed antenna has a low profile with the thickness of the antenna including the two MS layers being 0.07 lambda(0). The simulated and measured results show that using the proposed technique, the operating frequency can be tuned from 2.55 to 3.45 GHz with a fractional tuning range of around 28%. The antenna provides a minimum gain of 5.3 dB with the peak gain being 8.3 dB. The efficiency of the proposed antenna is more than 90% over its tuning range.