Abstract: Using simulation and experiment methods, a compact, coplanar, and cover all the operating bands of 2.4/5.2/5.8/GHz WLAN and 2.5/3.5/5.5GHz WiMAX systems of laptop antenna were designed. The antenna adopts coupling feed mode, by adjusting the size of the rectangular radiating surface and L-typed structure, and the dimension of the slotcoupling to arouse the resonant frequency of 25GHz and 55GHz; through cutting a U-shaped slit in the L-type radiation surface to achieve the resonance point of 3.5GHz, the length of the U-shaped is 1/4λ at the resonance point of about 4GHz. The antenna shows an entire area is only 7.5 mm× 17.5 mm (not including the system ground plane). In the procedure of design, through changing the gaps between the rectangular and L-shaped radiator can adjust the strength of the resonance point, but also realize the matching of input and output impedance. When mounted at the top edge of the display panel in the laptops, three wide operating bands for covering all the desired operating bands of WLAN/WiMAX systems are obtained and the antenna has a good radiation characteristics. The optimizations by using the simulator software Ansoft HFSS were performed, and an actual model has been prototyped for experimental measurements, the measured and simulated results are in good agreement.

Key words: multi-band; miniaturization; laptop antennas; coupling antennas; WLAN; WiMAX