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This communication presents an omnidirectional rectenna array with an enhanced RF power distributing strategy. The proposed rectenna array consists of three bidirectional subarray antennas, a $3\times $ 3 RF power distributing network, and a three-element rectifier array. Utilizing the $3\times $ 3 network to redistribute the varying RF power received by the three antennas, the RF-to-dc power conversion efficiency of the rectenna array can be enhanced under the illumination of electromagnetic (EM) waves with arbitrary incident angles. Measurement results reveal that the proposed rectenna array has an improved omnidirectional-harvesting capability compared with the design without RF power distributing strategy, thus can be readily used for RF energy-harvesting applications. [ABSTRACT FROM AUTHOR]

The millimeter-wave (mmWave) band will be used for the fifth-generation communication systems. In this paper, 60-GHz mmWave channel measurements and modeling are carried out for indoor office environments. The rotated directional antenna-based method and uniform virtual array-based method are adopted and compared to investigate the 60-GHz channel in a 3-D space, simultaneously covering azimuth and coelevation domains. The multipath component parameters including power, delay, azimuth, and elevation angles are estimated with the space-alternating generalized expectation–maximization estimation algorithm, and then processed with the K-means clustering algorithm. An extended Saleh–Valenzuela model with both delay and angular cluster features is used to characterize the measured channel, and the intercluster and intracluster parameters are extracted. We find that the azimuth departure angles are diverse and highly related to the antenna position and measurement environment, while the elevation departure angles are more related to the antenna height difference and confined in a relatively small direction range. The azimuth angle spread is much larger than the elevation angle spread either in global level or in cluster level. The results agree with the studies in the literature and channel models in IEEE standards. [ABSTRACT FROM PUBLISHER]

Uniform leaky-wave antennas (LWAs) with limited length have suffered from the presence of high-level side lobes, which could lead to the reception of unwanted noise especially when the LWA is short. This communication examines how the phase constant of a short LWA can be manipulated to achieve side lobe suppression. The tapering of the phase constant is shown to result in higher order “image patterns,” which can be used advantageously for side lobe suppression. Validation of this principle is given by a cosine-shaped width-tapering profile design of a half-mode substrate-integrated waveguide (HMSIW) LWA. The measured results show that the side lobe level (SLL) of a short ($1.4 \lambda _0$) HMSIW LWA has been suppressed to below -16\;\dB in the entire space wave leakage region using this tapering profile. [ABSTRACT FROM PUBLISHER]