Electromagnetic waves carrying orbital angular momentum (OAM and vortex waves) attract much attention due to their specific characteristics and prospects for use in wireless communication, biomedical engineering, and imaging. Vortex waves are complex spatial entities; therefore, their stable generation is a quite complicated task, especially in the radio frequency and terahertz wave domains, considering that the corresponding antennas must be precisely adjusted. Such adjusting is very difficult to achieve for flexible antennas, which are now being actively introduced into practice. Here, we propose a design of a flexible antenna that is able to stably generate waves carrying OAM even when being subjected to some bending. The antenna is composed of a ring-shaped resonator made of a highly conductive graphene film deposited on a thin polydimethylsiloxane substrate. The antenna is operated on two mutually orthogonal degenerate TM m 1 modes excited by two supply strip lines to generate vortex waves with a desired topological charge. We verify this ability numerically and in a microwave experiment on two antenna prototypes deriving the OAM mode purity by changing the bending radius of the antenna bearing surface, giving it either positive or negative curvature. The obtained experimental results confirm that the antenna has good performance and can be used for flexible electronic devices and communication systems.

1.
J. E.
Curtis
and
D. G.
Grier
, “
Structure of optical vortices
,”
Phys. Rev. Lett.
90
,
133901
(
2003
).
2.
S. M.
Mohammadi
,
L. K. S.
Daldorff
,
J. E. S.
Bergman
,
R. L.
Karlsson
,
B.
Thide
,
K.
Forozesh
,
T. D.
Carozzi
, and
B.
Isham
, “
Orbital angular momentum in radio—A system study
,”
IEEE Trans. Antennas Propag.
58
,
565
572
(
2010
).
3.
Y.
Yan
,
G.
Xie
,
M. P. J.
Lavery
,
H.
Huang
,
N.
Ahmed
,
C.
Bao
,
Y.
Ren
,
Y.
Cao
,
L.
Li
,
Z.
Zhao
,
A. F.
Molisch
,
M.
Tur
,
M. J.
Padgett
, and
A. E.
Willner
, “
High-capacity millimetre-wave communications with orbital angular momentum multiplexing
,”
Nat. Commun.
5
,
4876
(
2014
).
4.
S. K.
Noor
,
M. N.
Mohd Yasin
,
A. M.
Ismail
,
M. N.
Osman
,
P. J.
Soh
,
N.
Ramli
, and
A. H.
Rambe
, “
A review of orbital angular momentum vortex waves for the next generation wireless communications
,”
IEEE Access
10
,
89465
89484
(
2022
).
5.
X.
Wang
,
Z.
Nie
,
Y.
Liang
,
J.
Wang
,
T.
Li
, and
B.
Jia
, “
Recent advances on optical vortex generation
,”
Nanophotonics
7
,
1533
1556
(
2018
).
6.
J.
Xu
,
Y.
Guo
,
P.
Yang
,
R.
Zhang
,
X.
Zhai
,
S.
Huang
, and
K.
Bi
, “
Recent progress on RF orbital angular momentum antennas
,”
J. Electromagn. Waves Appl.
34
,
275
300
(
2020
).
7.
F.
Tamburini
,
E.
Mari
,
B.
Thidé
,
C.
Barbieri
, and
F.
Romanato
, “
Experimental verification of photon angular momentum and vorticity with radio techniques
,”
Appl. Phys. Lett.
99
,
204102
(
2011
).
8.
E.
Mari
,
F.
Spinello
,
M.
Oldoni
,
R. A.
Ravanelli
,
F.
Romanato
, and
G.
Parisi
, “
Near-field experimental verification of separation of OAM channels
,”
IEEE Antennas Wireless Propag. Lett.
14
,
556
558
(
2015
).
9.
Z.
Zhang
,
S.
Xiao
,
Y.
Li
, and
B.-Z.
Wang
, “
A circularly polarized multimode patch antenna for the generation of multiple orbital angular momentum modes
,”
IEEE Antennas Wireless Propag. Lett.
16
,
521
524
(
2017
).
10.
M.
Barbuto
,
F.
Trotta
,
F.
Bilotti
, and
A.
Toscano
, “
Circular polarized patch antenna generating orbital angular momentum
,”
Prog. Electromagn. Res.
148
,
23
30
(
2014
).
11.
H.
Feng
,
L.
Ye
,
Y.
Zhang
,
W.
Li
,
H.
Chen
, and
Q. H.
Liu
, “
Bidirectional multi-mode microwave vortex beam generation enabled by spoof surface plasmon polaritons
,”
Appl. Phys. Lett.
117
,
241601
(
2020
).
12.
Y.
Pan
,
S.
Zheng
,
J.
Zheng
,
Y.
Li
,
X.
Jin
,
H.
Chi
, and
X.
Zhang
, “
Generation of orbital angular momentum radio waves based on dielectric resonator antenna
,”
IEEE Antennas Wireless Propag. Lett.
16
,
385
388
(
2017
).
13.
J.
Ren
and
K. W.
Leung
, “
Circular polarized patch antenna generating orbital angular momentum
,”
Appl. Phys. Lett.
112
,
131103
(
2018
).
14.
K.
Zhang
,
Y.
Wang
,
Y.
Yuan
, and
S.
Burokur
, “
A review of orbital angular momentum vortex beams generation: From traditional methods to metasurfaces
,”
Appl. Sci.
10
,
1015
(
2020
).
15.
D.
Baran
,
D.
Corzo
, and
G.
Blazquez
, “
Flexible electronics: Status, challenges and opportunities
,”
Front. Electron.
1
,
594003
(
2020
).
16.
H.
Zhang
,
Y.
Lan
,
S.
Qiu
,
S.
Min
,
H.
Jang
,
J.
Park
,
S.
Gong
, and
Z.
Ma
, “
Flexible and stretchable microwave electronics: Past, present, and future perspective
,”
Adv. Mater. Technol.
6
,
2000759
(
2021
).
17.
M.
Zhang
,
L.
Huang
,
J.
Chen
,
C.
Li
, and
G.
Shi
, “
Ultratough, ultrastrong, and highly conductive graphene films with arbitrary sizes
,”
Adv. Mater.
26
,
7588
7592
(
2014
).
18.
R.
Song
,
Q.
Wang
,
B.
Mao
,
Z.
Wang
,
D.
Tang
,
B.
Zhang
,
J.
Zhang
,
C.
Liu
,
D.
He
,
Z.
Wu
, and
S.
Mu
, “
Flexible graphite films with high conductivity for radio-frequency antennas
,”
Carbon
130
,
164
169
(
2018
).
19.
H.-R.
Zu
,
B.
Wu
,
Y.-H.
Zhang
,
Y.-T.
Zhao
,
R.-G.
Song
, and
D.-P.
He
, “
Circularly polarized wearable antenna with low profile and low specific absorption rate using highly conductive graphene film
,”
IEEE Antennas Wireless Propag. Lett.
19
,
2354
2358
(
2020
).
20.
J.
Zhang
,
R.
Song
,
X.
Zhao
,
R.
Fang
,
B.
Zhang
,
W.
Qian
,
J.
Zhang
,
C.
Liu
, and
D.
He
, “
Flexible graphene-assembled film-based antenna for wireless wearable sensor with miniaturized size and high sensitivity
,”
ACS Omega
5
,
12937
12943
(
2020
).
21.
C.
Fan
,
B.
Wu
,
R.
Song
,
Y.
Zhao
,
Y.
Zhang
, and
D.
He
, “
Electromagnetic shielding and multi-beam radiation with high conductivity multilayer graphene film
,”
Carbon
155
,
506
513
(
2019
).
22.
F.
Shen
,
J.
Mu
,
K.
Guo
, and
Z.
Guo
, “
Generating circularly polarized vortex electromagnetic waves by the conical conformal patch antenna
,”
IEEE Trans. Antennas Propag.
67
,
5763
5771
(
2019
).
23.
J.
Jiang
,
S.
Yu
,
N.
Kou
,
Z.
Ding
, and
Z.
Zhang
, “
Generation of orbital angular momentum vortex beams with cylindrical and conical conformal array antennas
,”
Int. J. RF Microwave Comput. Aided Eng.
32
,
e22914
(
2022
).
24.
J.
Huang
, “
Circularly polarized conical patterns from circular microstrip antennas
,”
IEEE Trans. Antennas Propag.
32
,
991
994
(
1984
).
25.
R.
Garg
,
P.
Bhartia
,
I.
Bahl
, and
A.
Ittipiboon
,
Microstrip Antenna Design Handbook
(
Artech House
,
London
,
UK
,
2001
).
26.
IEEE 802.11-2016: IEEE Standard for Information Technology—Telecommunications and Information Exchange Between Systems: Local and Metropolitan Area Networks—Specific Requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications (IEEE, 2016), see https://standards.ieee.org/ieee/802.11/5536/
27.
S.
Zheng
,
X.
Hui
,
X.
Jin
,
H.
Chi
, and
X.
Zhang
, “
Transmission characteristics of a twisted radio wave based on circular traveling-wave antenna
,”
IEEE Trans. Antennas Propag.
63
,
1530
1536
(
2015
).
28.
F.-C.
Mao
,
M.
Huang
,
C.-F.
Yang
,
T.-H.
Li
,
J.-L.
Zhang
, and
S.-Y.
Chen
, “
Orbital angular momentum generation using circular ring resonators in radio frequency
,”
Chin. Phys. Lett.
35
,
020701
(
2018
).
29.
Z.
He
,
Y.
Wang
,
X.
Wang
,
A. S.
Kupriianov
,
V. R.
Tuz
, and
V. I.
Fesenko
, “
Multi-band orbital angular momentum mode-division multiplexing by a compact set of microstrip ring-shaped resonator antenna
,”
Opt. Express
30
,
46209
46226
(
2022
).
30.
V.
Fesenko
and
G.
Tkachenko
, “
Modeling of 1-D photonic bandgap microstrip structures
,” in
International Workshop on Optoelectronic Physics and Technology
, Kharkov, Ukraine (IEEE,
2007
), pp.
42
43
.
31.
J. D.
Jackson
,
Classical Electrodynamics
(
John Wiley & Sons, Inc
.,
New York
,
1962
).
32.
A. S.
Kupriianov
,
V. V.
Khardikov
,
K.
Domina
,
S. L.
Prosvirnin
,
W.
Han
, and
V. R.
Tuz
, “
Experimental observation of diffractive retroreflection from a dielectric metasurface
,”
J. Appl. Phys.
133
,
163101
(
2023
).
33.
L.
Torner
,
J. P.
Torres
, and
S.
Carrasco
, “
Digital spiral imaging
,”
Opt. Express
13
,
873
881
(
2005
).
34.
J.
Pinnell
,
I.
Nape
,
B.
Sephton
,
M. A.
Cox
,
V.
Rodríguez-Fajardo
, and
A.
Forbes
, “
Modal analysis of structured light with spatial light modulators: A practical tutorial
,”
J. Opt. Soc. Am. A
37
,
C146
C160
(
2020
).
You do not currently have access to this content.