A compact multiband bow-tie dipole slot antenna fed by coplanar waveguide (CPW) is proposed in this paper. Multiple resonant mode technique and notch-band technique have been combined in this design to form triple-band operation just by adding single elements. Based on this, a pair of hairpin-shaped branches is implemented on each arm of the bow-tie slot antenna. A notch-band property is achieved compared with the original wideband bow-tie antenna (without branches). Meanwhile, a new lower resonant frequency is obtained by using this kind of structure, which means the size is compact in nature and the triple-band operation is achieved. The notch-band and lower resonant frequency can be tuned by changing the length of the branch. The parameters of the antenna, including reflection coefficients, current distributions, radiation patterns and gain, are achieved by numerical simulations and measurements. The results indicate that the slot size of the proposed antenna is 52.4 mm×22.3 mm, and the proposed antenna can offer triple-band operation at 2.39-2.50 GHz (4.5%), 3.38-3.79 GHz (11.4%) and 4.87-6.23 GHz (24.5%), which is suitable for WLAN in the 2.4/5.2/5.8-GHz bands and WiMAX in the 3.5/5.5-GHz bands.
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