Uniplanar Printed Coupled-Fed PIFA With a Band-Notching Slit for WLAN/WiMAX Operation in the Laptop Computer

A small-size uniplanar printed antenna suitable for 2.4/5.2/5.8 GHz WLAN and 2.5/3.5/5.5 GHz WiMAX operations is presented. The antenna is a coupled-fed PIFA and shows a height of 9 mm and a width of 13 mm only, when mounted at the top edge of the display panel in the laptop computer. The multiband operation is achieved by using the coupling feed and further embedding a band-notching slit in the radiating arm of the PIFA. With the coupling feed, two wide operating bands can be generated at about 2.5 and 5.5 GHz for the PIFA. By further embedding the slit of length about a quarter-wavelength at about 4 GHz, a band-notching characteristic at about 4 GHz is obtained, which leads to an additional resonance at about 3.5 GHz and shows very small effects on the desired 2.5 and 5.5 GHz bands. This behavior results in successful excitation of an additional resonant mode for 3.5 GHz WiMAX operation. Hence, with no increase in the antenna size, three wide operating bands for covering all the desired operating bands of WLAN/WiMAX systems are achieved for the proposed PIFA. Details of the design considerations are presented, and results of the fabricated prototype are discussed.