No abstract

In this paper, we propose a dual-broadband multiple-input multiple-output (MIMO) indoor base station antenna for 2G/3G/LTE systems. The proposed MIMO antenna has a low profile with its overall dimensions of 220×220×42 mm 3 and utilizes both spatial and polarization diversities. The antenna operates at 800-960 and 1700-2700 MHz simultaneously, with the return loss of higher than 14 dB across both frequency bands. The isolations of the antenna are 18 and 25 dB, with antenna gains of 3.6 and 7.2 dBi for the lower and upper frequency bands, respectively. The proposed MIMO antenna is designed and fabricated with its practical deployment in mind, such as the durability and overall low cost. Comparing with existing commercial 2G/3G/LTE antennas, our proposed design offers a more compact size and simpler feeding structure.INDEX TERMS Base station antenna, long term evolution (LTE), multiple-input multiple-output (MIMO).

No abstract

In this paper, we propose a reconfigurable metasurface antenna for beam switching applications. The reconfigurable metasurface is formed by uniformly distributed double-split square rings loaded with positive-intrinsic-negative (PIN) diodes for dual operations of a wave reflector and a wave director. Specifically, when the PIN diodes are forward biased, an epsilon-negative (ENG) metasurface is realized which reflects all incident waves with appropriate polarization; when the diodes are reverse biased, at the same operating frequency, a mu-near-zero (MNZ) metasurface is acquired which directs wave propagation. For excitation, a dipole radiator loaded with the same type of PIN diode is designed. Simulation and measurement results show good agreement and verify the beam switching functionality of the proposed metasurface antenna.

No abstract

No abstract

No abstract

Development and optimization of printed spiral coils have significant impacts on the power transfer efficiency (PTE) and operating range for magnetic resonant wireless power transfer (WPT) applications. In this paper, the effects of different material losses (substrate and conducting coating) of printed coils are considered and experimentally studied. For the purposes of comparison and finding the dominating losses, lossy loaded capacitors with equivalent series resistances have also been investigated. A four-coil system with an external capacitor-loaded (ECL) magnetic resonant WPT system is considered, and a self-resonant coil is designed and compared. Results show that the ECL resonant coil has higher PTE than the self-resonant coil with the same size and distance between the transmitting and receiving coils. Through observing the simulated results and analyzing experimental data, it can be concluded that the dominant cause of the decrease in PTE of this ECL-WPT system is the strip resistive loss of coil of 57% (0.891 dB) and the ohmic loss in ECL of 37% (0.568 dB). Meanwhile, the substrate loss significantly impacts on the PTE of the self resonant coil. The overall measured PTE is about 66% of the ECL coil at a distance of 50 mm when the above loss factors are considered. The measured results are in good agreement with the analysis and simulations.