6772 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 66, NO. 12, DECEMBER 2018
Electrically Small, Low-Profile, Planar, Huygens
Dipole Antenna With Quad-Polarization Diversity
Ming-Chun Tang , Senior Member, IEEE, Zhentian Wu, Ting Shi, Student Member, IEEE,
and Richard W. Ziolkowski, Fellow, IEEE
Abstract—An electrically small, low profile, planar, Huygens
dipole antenna with four reconfigurable polarization states is
presented. The design incorporates both electric and magnetic
near-field resonant parasitic elements and a reconfigurable driven
element. The four polarization states include two orthog-
onal linear polarized (LP) and two circular polarization
(LHCP and RHCP) states. A 1.5 GHz prototype was fabricated
(partially with 3-D additive manufacturing), assembled, and
tested. The measured results, in good agreement with their
simulated values, demonstrate that even with its simple configu-
ration, electrically small size (ka = 0.944), and low-profile height
(0.0449λ
0
), this reconfigurable Huygens antenna possesses stable
broadside radiation performance in all of its four polarization
states. The measured results demonstrate that in its x( y)-LP
state, the peak realized gain, front-to-back ratio, and radiation
efficiency values are, respectively, ∼3.03 dBi (2.97 dBi), ∼10.7 dB
(9.9 dB), and ∼68.2% (67.5%). For the LHCP (RHCP) states,
they are, respectively, ∼2.82 dBi (2.74 dBi), ∼11.4 dB (12.5 dB),
and ∼67.1% (65.9%).
Index Terms—Electrically small antennas (ESAs), Huygens
dipole antennas, low-profile antennas, near-field resonant par-
asitic (NFRP) elements, polarization-reconfigurable antennas.
I. INTRODUCTION
E
LECTRICALLY small antennas (ESAs) with high direc-
tivity have received increasing attention in recent years.
They provide significant advantages for many space-limited
Manuscript received February 11, 2018; revised July 23, 2018; accepted
September 4, 2018. Date of publication September 13, 2018; date of current
version November 30, 2018. This work was supported in part by the
National Natural Science Foundation of China under Contract 61471072,
in part by the Graduate Scientific Research and Innovation Foundation of
Chongqing, China, under Contract CYB18069, in part by the Opening Subject
of the State Key Laboratory of Millimeter Waves under Contract K201732,
in part by the Funding of the Innovative Leading Talents in Science and
Technology of Chongqing under Contract CSTCCXLJRC201705, in part by
the Funding of the Leading Research Talent Cultivation Plan of Chongqing
University under Contract cqu2017hbrc1A08, in part by the Funding of the
Young Backbone Teachers in Colleges and Universities of Chongqing under
Contract 0307001104102, in part by the Fundamental Research Funds for
the Central Universities under Contract 2018CDQYTX0025, and in part by
the Australian Research Council under Grant DP160102219. (Corresponding
author: Ming-Chun Tang.)
M.-C. Tang, Z. Wu, and T. Shi are with the Key Laboratory of Dependable
Service Computing in Cyber-Physical Society, Ministry of Education, College
of Communication Engineering, Chongqing University, Chongqing 400044,
China, and also with the State Key Laboratory of Millimeter Waves, Southeast
University, Nanjing 210096, China (e-mail: tangmingchun@cqu.edu.cn).
R. W. Ziolkowski is with the Global Big Data Technologies Centre,
University of Technology Sydney, Ultimo, NSW 2007, Australia, and also
with the Department of Electrical and Computer Engineering, The University
of Arizona, Tucson, AZ 85721 USA (e-mail: richard.ziolkowski@uts.edu.au).
Color versions of one or more of the figures in this paper are available
online at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TAP.2018.2869645
wireless platforms associated, for example, with long-distance
and point-to-point communication systems [1], [2]. The pursuit
of higher directivity ESAs has led to a variety of designs.
Nevertheless, Huygens sources, which utilize pairs of magnetic
and electric radiators to achieve the desired directive outcome,
possess intrinsic advantages. In particular, the high directivity
is obtained without the need to load the radiator with additional
constructs such as periodic electromagnetic band gap (EBG)
structures [3], slot structures [4], or reflector elements [5].
These constructs generally increase the overall size and profile
of the antenna system significantly. A variety of Huygens
source ESAs have been reported with different arrangements,
including spherical wires [6], curved wires [7], and planar
strips [8]. Recently, we have also developed several Huy-
gens dipole ESAs using near-field resonant parasitic (NFRP)
technologies [9]. These include 3-D structures [10], [11],
multilayered structures [12], [13], and non-Foster designs [14].
However, it is expected that Huygens source ESAs could be
even more useful if they were versatile. For instance, anten-
nas with polarization reconfigurability have many advantages.
These include mitigating polarization mismatch, improving
system capacity, reducing channel interference, and realiz-
ing multiple transmission channels for frequency reuse [15].
Therefore, it would be highly desirable to enable polar-
ization reconfigurability in an electrically small Huygens
source antenna. Such a polarization diverse ESA would be
quite suitable for many modern compact wireless applica-
tions [16], [17], especially for narrowband multiple-input
multiple-output (MIMO) communication systems [18] and
narrowband wireless fidelity (WiFi) connections [19].
A number of antennas with polarization reconfigura-
bility have been reported in the literature over several
decades [20]–[27]. Generally, the methods to realize polar-
ization diversity can be divided into three categories. The
first employs reconfigurable radiating elements [20]–[22].
The second relies on reconfigurable feeding networks
[23]–[25]. The third resorts to reconfigurable parasitic peri-
odic structures [26], [27]. Unfortunately, none of these meth-
ods prove to be useful individually in the design of a
polarization-reconfigurable Huygens source ESA. Specifically,
the first method would necessitate the placement of p-i-n
diodes/switches on both the magnetic and the electric NFRP
elements, the actual radiators. Thus, a large number of p-i-
n diodes would be needed to simultaneously control both of
them. In turn, this would lead to an increase in the difficulties
in the design and assembly of the antenna, especially with
0018-926X © 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.
See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.