Abstract
This paper investigates uni-/multi-cast and orbital angular momentum (OAM) mode data transmission in orthogonal directions by the utilization of a new circular antenna array, operating at 28 GHz. In the horizontal plane the proposed antenna array operates as multimode transmitter (i.e., it provides broad-, uni- and/or multi-cast communication), while in the vertical direction OAM transmission occurs (i.e., it is capable of generating up to 15 spatially orthogonal OAM modes). Antenna array is designed using twelve, low-complexity, electromagnetically coupled microstrip patch antennas with high radiation efficiency. Each of these can transmit power of equivalent order of magnitude in both horizontal (i.e., broadside radiation pattern) and vertical direction (i.e., endfire radiation pattern) over electromagnetic waves of orthogonal electric components. This property leads to the formation of uni-/multi-cast and OAM modes in the horizontal plane and vertical direction, respectively. Antenna was tested through full-wave electromagnetic analysis and measurements in terms of impedance matching, mutual coupling and radiation pattern: good agreement between simulated and measurement results was observed. Specifically, it presents up to 8.65 dBi and 6.48 dBi realized gain under the uni-cast (in the horizontal plane) and OAM mode (in the vertical plane), respectively. The proposed antenna array is perfect candidate for high spectral efficiency data transmission for 5G and beyond wireless applications, where orthogonality in communication links and OAM multiplexing is a requirement.
Highlights
The development of wireless multimedia communication techniques over the last years requires the design of new, high-directive1, compact2, reconfigurable[3], multiple-input–multiple-output (MIMO)[4] and meta-surface antenna systems[5]
A circular antenna array consisting of patch antenna elements, which lay in parallel to the horizontal plane, is able to form orbital angular momentum (OAM) modes, given an appropriate excitation, and transmit power in the vertical direction, e.g.,18,20
The proposed antenna serves as WSNgateway through the drone. Another application is the communication between swarms of connected drones equipped with the circular array, where drone-to-drone communication is established along the horizontal plane, i.e., through the uni- and multi-cast modes, while drone-to-BS, which is placed on some or a single drone, communication occurs in vertical direction, by utilizing the OAM modes
Summary
The development of wireless multimedia communication techniques over the last years requires the design of new, high-directive1, compact2, reconfigurable[3], multiple-input–multiple-output (MIMO)[4] and meta-surface antenna systems[5]. The mode-based circular array radiation is promising in terms of spectrum e fficiency[6], since it can be used for orthogonal data transmission by utilizing, at the same time, spatial and frequency resources. The novelty of this work is the solution of this engineering problem: how to design a circular antenna array, able to form spatially separated uni-/multi-cast and OAM modes. The solution of this problem is the utilization of radiating elements, which transmit power in two orthogonal directions, over two orthogonal electric components. To the best of our knowledge, it is the first antenna that has been designed and fabricated at 28 GHz which presents this double functionality
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