Highly efficient planar monopole antennas for 1.8/3.3 GHz dual band GSM/WiMAX operations

In this paper, a novel and compact dual-band planar monopole antenna with well-tuning mechanisms of each individual band is proposed. This antenna is fabricated on a low-cost, easily available FR4 substrate by using etching or milling machines. The lower operation frequency can be adjusted to cover GSM 1800 band (1805 - 1880 MHz), and the upper band covers Worldwide Interoperability for Microwave Access (WiMax) band (3.3 GHz) for more than 200 MHz. After setting the desired operation frequencies, a thin wire and microstrip pad is designed to achieve dual-band matching. The overall antenna area is compact and effectively shrinks to 0.018λ₀². Compared with other miniature antennas, our proposed antenna still maintains high efficiency. The measured antenna gains are from -1.78 to -1.12 dBi and from 1.05 to 2 dBi at its low and high frequency band, respectively.