Utilization of Photon Orbital Angular Momentum in the Low-Frequency Radio Domain

Abstract

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Circular Polarized Patch Antenna Generating Orbital Angular Momentum

“…In particular, we show that the higher order modes of a circularly polarized patch antenna can be used to generate different OAM states. This solution is clearly cheaper, lighter and more compact compared to the ones already proposed [5][6][7][8][9]. Moreover, although OAM cannot be used to improve the performances of a communication system except in very particular cases [12], the proposed solution can be useful to experimentally investigate the properties of the OAM or to extend to microwave frequencies imaging and identification techniques based on OAM and developed in the optical regime [13].…”

“…Recently, it has been shown that an electromagnetic (EM) field with a non-zero OAM can be also generated in the microwave range using standard antenna systems [5]. Starting from this first demonstration, several systems generating EM fields with non-zero OAM have been proposed [5][6][7][8][9]. Such systems are based on two different approaches.…”

“…Such systems are based on two different approaches. The first one consists of a circular antenna array in which the different elements are fed with signals having the same amplitude and a progressive phase shift, such that the total delay between the first and the last element is an integer multiple l of 2π [5,6]. A variant of this approach is presented in [7] and makes use of a time-switched array.…”

Horn Antenna Generating Electromagnetic Field With Orbital Angular Momentum

“…The phase rotation factor e −jlϕ [3] determines the spatial phase distribution structure of the vortex beam, in which l represents the mode of the orbital angular momentum. Moreover, the OAM beams with different modes are mutually orthogonal and have different spatial structures.…”

“…In the article [9,10], the asymmetric structure of antennas lead to the asymmetry of the radiation field. The second is to create phase difference using multi-point feeding, such as the circular patch antenna [11], circular antenna array [12][13][14][15][16], the half mode substrate integrated waveguide antenna [17], etc. Antennas in [11,17] fed with two same signals but with a π/2 phase shift to get phase factor e −jlϕ .…”