In this paper, the design and performance evaluation of a switched-beam antenna array to operate in the 60 GHz band for short-range WPAN applications is presented. In order to overcome the high path-loss attenuation at millimeter-wave frequencies and, moreover, to achieve high data rate wireless communications, highly directive antennas are required. In addition, beam-steering capabilities are also needed to deal with the high user random mobility and human-body shadowing characteristic of indoor environments. For these reasons, we propose a design based on a five by five slot antenna array, in which each single element can be selected individually, and a dielectric inhomogeneous gradient-index flat lens to steer and enhance the radiation in a particular direction. A total of 25 fixed high-gain beams can be selected individually to scan in both theta and phi directions. Our measurement results show that we can achieve up to 17.25 dB of broadside gain, and beam-steering capabilities from +20 degrees to -20 degrees with more than 15 dB of gain, and up to 52 with around 12.8 dB, with low-side lobe levels, in the entire frequency band of interest (from 57 to 64 GHz).
