A dual-band printed dipole antenna with integrated balun feed is given in this paper. First, the fork-shaped slot is etched on the arms of the printed dipole antenna to achieve the dual-band operation with resonances at WLAN bands. The radiating element without balun is optimized and operates at 2.4 GHz (2180-2750 MHz) and 5.2 GHz (5040 MHz-5480 MHz) where return loss is less than -10 dB. In order to further get a lager bandwidth, a modified Marchand balun is introduced for dual-band operation, which can provide two resonances in each band to enhance impedance bandwidth. By co-designing the radiating element with the dual-band balun, an antenna covering 2150-2750 MHz and 5050-6230 MHz has been achieved. The design equations for modified balun have been presented and agreement between calculations and measurements is good.
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