Compact microstrip antenna based on fractal metasurface with low radar cross section and wide bandwidth

Compact microstrip antenna based on
fractal metasurface with low radar cross
section and wide bandwidth
1. Introduction
The microstrip antenna is a conventional kind of
antenna for radar application which it is used for
various applications such as communication
system, medical application, mobile services
and radar systems in missile
The radar cross section (RCS) of the antenna is
known as an important factor for some of these
applications. The radar cross section (RCS) is
noticed for stealth application by coating the
surface of an aircraft
The geometry of the antenna is presented in Fig.
2(a) and (b) for the ground layer and the feed
line, respectively, where the feed line is
connected to a 50 ohm SMA connector. As
shown here, the main slot is made in the circular
shape with 4 small rectangular slots which they
are rotated 45°. Then, the six dual ring
structures are added to the antenna as parasitic
loads and finally, a disk is placed at the center
for matching.
On the other hand, nowadays antennas with low
RCS have been noticed while the fractal
technique is one of the main methods for this
goal.
The microstrip circular slot antenna with a
straight feed line is selected as our basic
structure. We have investigated that we can
obtain wider bandwidth with a great
enhancement only by adding rectangular slot
and the dual ring structure. Finally, the circular
disk is located in the central part of the slot for
improving the matching of the antenna and the
fractal technique is used to reduce the radar
cross section.
The resonant frequency of the conventional slot
ring antenna can be obtained by Eq. (1) where
the C is the light speed and ε is the substrate
permittivity. Fig. 1 shows the antenna designing
step from a simple slot to the final antenna. The
resonance frequency of the slot antenna can be
obtained from:
Fig. 1. The four steps in antenna design from slot
antenna to slot antenna with the fractal ring.
Fig. 2. The antenna’s geometry (a) the ground layer
with parasitic elements, (b) the feed line geometry
and (c) the fabricated antenna.
The total size of the antenna is 40 × 40 mm2. It
is designed on FR4 with the thickness of
1.6 mm as a low cost substrate with the
permittivity of 4.3 and loss tangent of 0.02. The
antenna all dimensions are a = 40 mm,
b = 3.65 mm, c = 4 mm, d0 = 27 mm,
d1 = 7.8 mm, d2 = 5.8 mm, d3 = 5.2 mm,
w = 1.6 mm and l = 20 mm. The fabricated
antenna is presented in Fig. 2(C).
The antenna radiation pattern for Phi = 0 and
Phi = 90 at 3 GHz and slot is known for their bidirectional radiation pattern in Phi = 0 and
Omnidirectional pattern in phi = 90 where the
antenna shows low cross polarization. Fig. 3
shows the antenna 2D radiation pattern for
simulation and experimental.
4] Sreenath
Reddy Thummaluru, Rajkishor Kumar, Rag
hvendra Kumar ChaudharyIsolation
enhancement and radar cross section
reduction of MIMO antenna with
frequency selective surface
IEEE Trans Antennas
Propag, 66 (3) (2018), pp. 15951600
Fig. 3. The antenna radiation 2D pattern (a) E-plane
at 3 GHz for Phi = 0° and (b) H-plane at 3 GHz for
Theta = 90°.
Exactly, this antenna has a compact size in
comparison with the other suggested model [25]
because we have combined the metasurface
layer inside of the ground layer. In addition, the
metasurface reduces the antenna frequency from
3.2 to 2.4 GHz.
References
[1]Claudia Vasanelli, Frank Bögelsack, Chr
istian WaldschmidtReducing the radar
cross section of microstrip arrays using
AMC structures for the vehicle
integration of automotive radars
IEEE Trans Antennas
Propag, 66 (3) (2018), pp. 14561464
[2]Merna Baharuddin, Victor Wissan, Josap
hat Tetuko
SriSumantyo, Hiroaki KuzeElliptical
microstrip antenna for circularly
polarized synthetic aperture radar
AEU-Int J Electron
Commun, 65 (1) (2011), pp. 62-67
[3] M. Zahir Joozdani, M. Khalaj
Amirhosseini, A. AbdolaliWideband
radar cross-section reduction of patch
array antenna with miniaturised
hexagonal loop frequency selective
surface
Electron Lett, 52 (9) (2016),
pp. 767-768