Tri-Band Monopole Antenna Covers WiMAX And WiFi Bands

July 16, 2010
Systems with mulitple wireless communications protocols require compact, low-cost, multiband antennas. Recently, a compact tri-band monopole antenna was proposed. It uses reactive loading, which was inspired by previous ...

Systems with mulitple wireless communications protocols require compact, low-cost, multiband antennas. Recently, a compact tri-band monopole antenna was proposed. It uses reactive loading, which was inspired by previous transmission-linemetamaterials (TL-MTM) work, and a "defected" groundplane. In doing so, it can meet the specifications of the WiFi and WiMAX standards while maintaining a small form factor. The antenna was developed by Jiang Zhu, Marco A. Antoniades, and George V. Eleftheriades from the University of Toronto's Edward S. Rogers Sr. Department of Electrical and Computer Engineering.

The loaded antenna can operate in two modes. The first resonance exhibits a dipolar mode over the lower WiFi band of 2.40 to 2.48 GHz. The second resonance has a monopolar mode over the 5.15-to-5.80-GHz upper WiFi band. The currents of the two modes are orthogonal to each other, resulting in orthogonal radiation patterns in the far field. The defected groundplane, which is formed by cutting an L-shaped slot out of one of the coplanar-waveguide (CPW) groundplanes, leads to the third resonance covering the WiMAX band from 3.30 to 3.80 GHz.

The 20.0-x-23.5-x-1.59-mm prototype exhibits good agreement between the measured and simulated S-parameters and radiation patterns. The measured radiation efficiencies are 67.4 percent at 2.45 GHz, 86.3 percent at 3.50 GHz, and 85.3 percent at 5.50 GHz. See "A Compact Tri-Band Monopole Antenna with Single-Cell Metamaterial Loading," IEEE Transactions On Antennas And Propagation, April 2010, p. 1031.

About the Author

Nancy Friedrich | RF Product Marketing Manager for Aerospace Defense, Keysight Technologies

Nancy Friedrich is RF Product Marketing Manager for Aerospace Defense at Keysight Technologies. Nancy Friedrich started a career in engineering media about two decades ago with a stint editing copy and writing news for Electronic Design. A few years later, she began writing full time as technology editor at Wireless Systems Design. In 2005, Nancy was named editor-in-chief of Microwaves & RF, a position she held (along with other positions as group content head) until 2018. Nancy then moved to a position at UBM, where she was editor-in-chief of Design News and content director for tradeshows including DesignCon, ESC, and the Smart Manufacturing shows.

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