Enhanced Gain Planar Inverted-F Antenna with Metamaterial Superstrate for UMTS Applications

Planar inverted-F antennas (PIFA) are widely used in wireless hand-held devices due to their small-size, moderate bandwidth and radiation patterns. However, the radiation patterns of such antennas degrade when placed very close to a conductive finite ground plane. In this paper, an engineered magnetic superstrate is introduced to enhance the gain of PIFA antennas. The engineered magnetic superstrate is based on the broad-side coupled split ring resonator (SRR) inclusions which have high real permeability value at the resonance frequency of the antenna. Numerical full-wave simulations are performed to analyze the entire radiating system (antenna with superstrate). By using the magnetic superstrate, a 3.2 dB improvement in the gain of the PIFA antenna working in the UMTS band was achieved. The total height of the proposed superstrate over the antenna is only λ0/14 where λ0 is the free-space wavelength at antenna’s resonance frequency. Thus, the antenna structure remains low profile, and is advantageous in cell-phone applications.