Concentric Circular Array Analysis to Overcome Divergence of Vortex Waves for 70 GHz Frequency Link

Orbital angular momentum (OAM) of waves, also known as vortex, offers a promising way to enhance communication link capacity and diversity. One of the advantages of vortex modal communication is that one can use different signal information within a fixed frequency band. There is no need to expand the frequency bandwidth, change the polarization, or wait for a time to transfer two-way communication. However, there is still work to be done before vortex communication can be considered as a potential for the next wireless network. One major issue when generating and receiving vortex high modes is the limitation of signal power level in comparison with normal waves. In this study we propose using different concentric circular array formations to overcome low power amounts for OAM modes. Through the use of a higher directive vortex mode, it is possible to increase the link budget and deal with the physical phenomena of divergence patterns. Different modes of 0, 1, and 2 are considered when tapering the array elements. The achieved directivity values were 23, 20, and 18 dB for 0, 10, and 16° angles. Helix antenna as the basic element is suggested in theory for a 70 GHz backhaul communication link.