A miniaturized volkswagen logo UWB antenna with slotted ground structure and metamaterial for GPS, WIMAX and WLAN applications

A novel concept of using slotted ground structure and a single circular split ring resonator (SRR) to achieve multiband operation from a miniaturized UWB antenna is presented in this paper. Initially, a miniaturized Volkswagen logo ultrawideband (UWB) antenna having −10 dB impedance bandwidth of about 124% (2.9–12.4 GHz) in simulation and 116.7% (3.1–11.8 GHz) under measurement is designed. This miniaturization leads to about 10% increment in −10 dB reflection coefficient bandwidth and about 66.71% reduction in the volume of the proposed UWB antenna as compared to the conventional circular antenna. In order to reconfigure the proposed UWB antenna to operate it at 1.5 (GPS), 3.5 (WiMAX), 5.2 and 5.8 GHz (WLAN) frequency bands, slotted ground structure with metamaterial is used. The proposed metamaterial is a circular SRR consisting of a single circular ring and is placed on the slotted ground structure of the proposed antenna to achieve 1.5 GHz band. The proposed configuration has a volume of 0.290λ₀ × 0.290λ₀ × 0.015λ₀ (30 × 30 × 1.6 mm³) at a lower resonating band of 2.9 GHz and is fabricated on a widely available FR4 substrate with a loss tangent of 0.02 and dielectric constant of 4.4. Simulated and experimental results show that the proposed design yields S₁₁ < −10 dB at the targeted frequencies. Good impedance matching, stable radiation characteristics with cross-polarization level less than −15 dB (both in E and H planes), VSWR < 2, average gain of 3.09 dBi and radiation efficiency of more than 85% are observed at the designed band when the antenna is fabricated and tested.