A multiband antenna loaded with metamaterial and slots for GPS/WLAN/WiMAX applications

A compact planar four band antenna loaded with metamaterial and slots for GPS, WLAN, and WiMAX applications, is presented in this letter. Initially, a dual-band (2.9 and 5.9 GHz) antenna is designed by etching trapezoidal shaped slots in the radiating patch and rectangular shaped slots in the ground plane. In order to make the dual band antenna to operate at more number of bands, two identical metamaterial unit cells are introduced in the ground plane. The introduction of metamaterial creates additional resonance at 1.5 and 5.2 GHz, respectively. The proposed design has a dimension of 0.21λ₀ × 0.23λ₀ × 0.01λ₀ at a lower frequency of 2.4 GHz, and operates at 1.5 (GPS), 2.4, 5.2 (WLAN), and 3.5 GHz (WiMAX) frequency bands, respectively. The proposed metamaterial negative permeability retrieval mechanism through waveguide medium is discussed in detail. The proposed design has measured S₁₁ < −10 dB bandwidth of about 6.06% (1.6–1.7 GHz), 8.33% (2.3–2.5 GHz), 5.55% (3.5–3.71 GHz), and 5.94% (4.9–5.2 GHz), respectively. Good impedance matching, stable radiation characteristics with low cross-polarization and an average gain of 2.25 dBi, are observed across the operational bandwidths, when the antenna is fabricated and tested.