Planar array with bidirectional elements for tunnel environments

Abstract

The growing demands for wireless communications in tunnel environments are driven by requests for maintaining uninterrupted internet access for users in tunnels as well as wireless connections for wireless sensors, security, and control networks. Nevertheless, wireless networks in tunnel environments are associated with technical challenges related to elongated wireless coverage in two opposite near-end-fire directions. Here, we introduce a low-profile bidirectional antenna that can be mounted on a large ground plane and that has a dual-magnetic-current mode exhibiting radiation patterns with 3-dB beamwidth coverage at near-end-fire angles. Furthermore, we realized a planar array with eight such bidirectional antennas that were configured as a sparse array in order to reduce the commonplace issues of mutual coupling and grating lobes. The radiation beams of the proposed antenna array can scan in the end-fire area (60° < φ < 120°, 45° < θ < 80°), with scanning gains of 11~15 dB in the near-end-fire directions. In addition, we demonstrate that the proposed array can adaptively generate a directional single beam or multiple beams according to the positions of users, which is suitable for intelligent communication systems with low power consumptions and high communication bandwidths in tunnel environments.

Theoretical analysis of a graphene quantum well hybrid plasmonic waveguide to design an inter/intra-chip nano-antenna

“…The scheme of a 1×5 array of HPWA based on the graphene quantum well is depicted in has a destructive effect on the intermediate broadside radiation pattern, which is related to the appearance of grating lobes [46,47]. It is due to the distance between the adjacent elements, which is approximately one wavelength and exceeds a half wavelength based on the product principle [46].…”

“…To eradicate the grating lobes, the distance between the elements should be decreased but it leads to the variation of mutual coupling between the adjacent elements. To set a balance between the mutual coupling and distance between the adjacent elements, the elements of single row array should be arranged as stair steps [47]. Also, when the phase of the input signal of each port is equal to each other, the shape of radiation patterns of even and odd modes remains unchanged compared with the single nano-antenna.…”

Broadband high‐efficiency high‐gain dual‐beam empty substrate integrated waveguide cavity‐backed filtenna

“…In wireless communication, the dual-beam antenna is important to cover bidirectional areas with reduced multipath and interference effects. 1,2 Especially in narrow and long tunnel environments, 3 such as subway and underground mine, wireless coverage is usually required in two opposite directions. Dual-beam antenna shows its application potential and has been widely explored recently.…”

S‐shaped planar antenna with 45° tilted bidirectional radiation pattern for motorcycle helmets

“…To the best of the authors' knowledge, antennas with bidirectional radiation and beam tilt characteristics have not been reported for helmet applications. While antennas with bidirectional radiation characteristics have been developed by utilizing improved microstrip antennas [3,4], back‐to‐back antennas [11,12], surface wave antennas [5], end‐fire antennas [13], shaped notch antennas [14], slot antennas based on a SIW transmission line [15], metamaterial inspired antennas [16], improved monopole antennas [17], and open‐ended waveguide antennas [18], these antennas are typically applied in outdoor MIMO base stations, coal mines, subways/street microcells, broadcasting base stations, indoor mobile robots, and intelligent transportation systems. As a result, antenna size for such applications is not a main concern, and these bulky antennas cannot be directly used for wearable devices such as helmets.…”