A center-feed dual-band dual-polarized circular microstrip antenna employing the curved slots on the ground is proposed. The proposed antenna radiates φ-polarization by introducing 10 units of curved slots symmetrically on the ground and θ-polarization by the coaxial probe at the center. The measured results show that the proposed antenna provides two resonant bands, TM01 and TM02 modes, covering the frequency bands of the WLAN (2.4-2.484 GHz) with an omnidirectional right-handed circular polarized (RHCP) radiation pattern and the WiMAX (3.3-3.6 GHz) with an omnidirectional horizontal polarized radiation pattern, respectively. In addition, the effects of the unit number of the curved slots and the width of the slots on the frequency ratio of these two resonant frequencies are studied. Furthermore, for the low profile of 0.056 λ0 and good omnidirectional characteristic, the antenna is suitable for the modern multi-band wireless communication systems.
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