Dual-band and Wideband Design of a Printed Dipole Antenna Integrated with Dual-band Balun

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 (2180–2750MHz) and 5.2GHz (5040 MHz–5480MHz) where return loss is less than −10 dB. In order to get a larger 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 bands has been achieved. The design equations for modified balun have been presented and agreement between calculation and measurement is good.