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This simple printed dipole antenna design provides adequate gain and a low-cost solution for high-data-rate 5-GHz WLANs.
Wireless local-area networks (WI.ANS) have gained popularity with the growth of mobile Internet services. WI.AN development in the 5-GHz band (the IEEE 802.11a and g standards) is especially attractive due to the high data rate (54 Mb/s) and greater number of allocated channels compared to 2.4-GHZ MAN systems. However, the wide bandwidth at 5 GHZ presents a challenge for RF designers, since wideband (5.15 to 5.85 GHz) antennas are more difficult to design than their narrowband 2.4-GHz counterparts. Fortunately, the authors have developed a wideband printed dipole antenna for coverage of the full 5-GHz band.
WLAN antennas are normally configured in an inverted-F (IFA) or inverted-L (ILA) form-basically a piece of metal bent into an F or L shape, respectively. However, a significant part of the antenna lies above the printed-circuit board (PCB), requiring support from foam or other materials. A more robust approach is to print it directly on the PCB, making the antenna planar and not requiring supporting foam.
The printed dipole antenna consists of two rectangular-shaped strips, typically a quarter wavelength long. The two arms of dipole must be fed differentially. Since the front-end module preceding the antenna is typically a single-ended design, a balun will be needed to make the transformation to...