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).
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.
The capabilities of the dual-band bidirectional dipole antenna to couple near-field with the metasurface have been investigated both numerically and experimentally. By properly positioning the radiating element with respect to the metasurface, the proposed antenna can emit in forward or in the backward direction. It is shown that the array of fractal closed ring resonators formed as the anisotropic metasurface can be excited to generate the opposite angular beams even though the reflection coefficient of the metasurface is high with the same value of 0.8. This is due to the fact that the conversion of evanescent to propagation waves from transmitting closely antenna to the far-zone existed. To our knowledge, this is the first report for a metasurface applied to dualband antenna with contrary beams. This proposed metasurface-based antenna concept may present new opportunities in the design of multifunctional antennas. V C 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:715-720, 2017; View this article online at wileyonlinelibrary.com.ABSTRACT: In this article, a simple hexagonal metamaterial is presented. Different from the design method of parameters optimization, the Figure 8 The corresponding dependencies of front-to-back ratio (FBR) as function of the distance k0/N. [Color figure can be viewed at wileyonlinelibrary.com]
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