High-gain shorted monopole antennas for concurrent access-point applications

Multiple-input multiple-output (MIMO) technology using multiple transmit/ receive antennas is considered one of the most promising approaches to higher throughput wireless systems. A lot of "lln" products are readily accessible in the marketplace although the IEEE has very recently ratified the IEEE 802.1 In standard in September 2009 [1]. To integrate more antennas into the wireless access point (AP) or router with similar device size remained, the antenna form factor becomes very important. Conventional external dipole antennas [2, 3] are widely used in many APs. However, they are not pleasing to the end user from an esthetic point of view and prone to be vandalized. Especially for concurrent dual-band operation that utilizes single-band antennas [4, 5], a typical AP incorporating six external antennas standing upright is thus formed as one example shown in [6]. In this Symposium, an internal multi-antenna system consisting of six short-circuited monopole antennas with high gain and good isolation is proposed. Among the six monopoles, three are designed for 2.4 GHz operation while the others are for 5 GHz operation. The antennas are carefully mounted on a circular ground to achieve a symmetrical MIMO structure. Both the antennas are short-circuited to the ground via the shorting portion, which is a helpful mechanic part for affixing the antennas.