Much attention has been paid to wireless local area network (WLAN) systems that conform to the IEEE 802.11n standard in which the MIMO-OFDM technique is the major technology to achieve a high level of throughput. Many types of multi-band antennas for these systems both in the 2.4-GHz (2.4-2.5 GHz) band of the IEEE 802.11b/g standard and in the 5-GHz (4.9-5.1 GHz, 5.15-5.35 GHz, 5.47-5.725 GHz) band of the IEEE 802.11a standard were studied, e.g., [1]. It was reported that a higher MIMO channel capacity is achieved using a dual-polarized antenna configuration compared to using a single-polarized antenna configuration [2]. We proposed 2.4/5-GHz dual-band horizontally-polarized omnidirectional antennas for WLAN base stations [3], but did not address a dual-band dual-polarized omnidirectional antenna configuration, which is required for dual-polarized MIMO WLAN systems. This paper proposes a 2.4/5-GHz dual-band antenna for WLAN base stations with a vertically/horizontally dual-polarized omnidirectional radiation pattern in the horizontal plane that satisfies the wide-band requirement for the IEEE 802.11n standard. We fabricated a prototype antenna and measured its characteristics. The structure of the antennas and their fundamental characteristics such as the measured scattering parameters, gain, radiation pattern, level deviation, and XPD of the antenna are shown.
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