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The Effect of Curvature on Resonance Frequency, Gain, Efficiency and Quality Factor of a Microstrip Printed Antenna Conformed on a Cylindrical Body for TM10 mode Using Different Substrates

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Curvature has a great effect on fringing field of a microstrip antenna and consequently fringing field affects effective dielectric constant and then all antenna parameters. A new mathematical model for resonance frequency, gain, efficiency and quality factor as a function of curvature is introduced in this paper. These parameters are given for TM 10 mode and using three different substrate materials RT/duroid-5880 PTFE, K-6098 Teflon/Glass and Epsilam-10 ceramic-filled Teflon.
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The Effect of Curvature on Resonance Frequency, Gain,
Efficiency and Quality Factor of a Microstrip Printed
Antenna Conformed on a Cylindrical Body
for TM
10
mode Using Different Substrates
Ali Elrashidi
1
, Khaled Elleithy
2
, Hassan Bajwa
3
1
Department of Computer and Electrical Engineering, University of Bridgeport, Bridgeport, CT 06604, USA
(aelrashi@bridgeport.edu)
2Department of Computer and Electrical Engineering, University of Bridgeport, Bridgeport, CT 06604, USA
(elleithy@bridgeport.edu)
3Department of Computer and Electrical Engineering, University of Bridgeport, Bridgeport, CT 06604, USA
(hbjwa@bridgeport.edu)
Abstract Curvature has a great effect on fringing field of a microstrip antenna and consequently fringing field affects
effective dielectric constant and then all antenna parameters. A new mathematical model for resonance frequency, gain,
efficiency and quality factor as a function of curvature is introduced in this paper. These parameters are given for TM
10
mode and using three different substrate materials RT/duroid-5880 PTFE, K-6098 Teflon/Glass and Epsilam-10
ceramic-filled Teflon.
Keywords Fringing field, curvature, effective dielectric constant, gain, efficiency, Q-factor, and Transverse Magnetic
TM
10
mode.
1. Introduction
Due to the unprinted growth in wireless applications and
increasing demand of low cost solutions for RF and
microwave communication systems, the microstrip flat
antenna, has undergone tremendous growth recently.
Though the models used in analyzing microstrip structures
have been widely accepted, the effect of curvature on
dielectric constant and antenna performance has not been
studied in detail. Low profile, low weight, low cost and its
ability of conforming to curve surfaces [1], conformal
microstrip structures have also witnessed enormous growth
in the last few years. Applications of microstrip structures
include Unmanned Aerial Vehicle (UAV), planes, rocket,
radars and communication industry [2]. Some advantages
of conformal antennas over the planer microstrip structure
include, easy installation (randome not needed), capability
of embedded structure within composite aerodynamic
surfaces, better angular coverage and controlled gain,
depending upon shape [3, 4]. While Conformal Antenna
provide potential solution for many applications, it has
some drawbacks due to bedding [5]. Such drawbacks
include phase, impedance, and resonance frequency errors
due to the stretching and compression of the dielectric
material along the inner and outer surfaces of conformal
surface. Changes in the dielectric constant and material
thickness also affect the performance of the antenna.
Analysis tools for conformal arrays are not mature and fully
developed [6]. Dielectric materials suffer from cracking due
to bending and that will affect the performance of the
conformal microstrip antenna.
2. Background
Conventional microstrip antenna has a metallic patch print-
ed on a thin, grounded dielectric substrate. Although the
patch can be of any shape, rectangular patches, as shown in
Figure 1 [7], are preferred due to easy calculation and mod-
eling.
Figure 1. Rectangular microstrip antenna
Fringing fields have a great effect on the performance of a
microstrip antenna. In microstrip antennas the electric filed
in the center of the patch is zero. The radiation is due to the
fringing field between the periphery of the patch and the
ground plane. For the rectangular patch shown in the
Figure 2, there is no field variation along the width and
thickness. The amount of the fringing field is a function of
the dimensions of the patch and the height of the substrate.
L
W
ɛ
r
y
x
L
ε
r
R
d
d
d
s
s
d
Higher the substrate, the greater is the fringing field.
Due to the effect of fringing, a microstrip patch antenna
would look electrically wider compared to its physical
dimensions. As shown in Figure 2, waves travel both in
substrate and in the air. Thus an effective dielectric constant
reff
is to be introduced. The effective dielectric constant
reff
takes in account both the fringing and the wave propagation
in the line.
Figure 2. Electric field lines (Side View).
The expression for the effective dielectric constant is
introduced by A. Balanis [7], as shown in Equation 1.
(1)
The length of the patch is extended on each end by  is a
function of effective dielectric constant and the
width to height ratio (W/h). can be calculated according
to a practical approximate relation for the normalized
extension of the length [8], as in Equation 2.
(2)
Figure 3. Physical and effective lengths of rectangular microstrip patch.
The effective length of the patch is L
eff
and can be
calculated as in Equation 3.
L
eff
    (3)
By using the effective dielectric constant (Equation 1) and
effective length (Equation 3), we can calculate the
resonance frequency of the antenna f and all the microstrip
antenna parameters.
Cylindrical-Rectangular Patch Antenna
All the previous work for a conformal rectangular
microstrip antenna assumed that the curvature does not
affect the effective dielectric constant and the extension on
the length. The effect of curvature on the resonant
frequency has been presented previously [9]. In this paper
we present the effect of fringing field on the performance of
a conformal patch antenna. A mathematical model that
includes the effect of curvature on fringing field and on
antenna performance is presented. The cylindrical
rectangular patch is the most famous and popular conformal
antenna. The manufacturing of this antenna is easy with
respect to spherical and conical antennas.
Effect of curvature of conformal antenna on resonant
frequency been presented by Clifford M. Krowne [9, 10] as:
(4)
Where 2b is a length of the patch antenna, a is a radius of
the cylinder, is the angle bounded the width of the patch,
represents electric permittivity and µ is the magnetic
permeability as shown in Figure 4.
Figurer 4. Geometry of cylindrical-rectangular patch antenna[9]
Joseph A. et al, presented an approach to the analysis of
microstrip antennas on cylindrical surface. In this approach,
the field in terms of surface current is calculated, while
considering dielectric layer around the cylindrical body. The
assumption is only valid if radiation is smaller than stored
energy[11]. Kwai et al. [12]gave a brief analysis of a thin
cylindrical-rectangular microstrip patch antenna which
includes resonant frequencies, radiation patterns, input
impedances and Q factors. The effect of curvature on the
characteristics of TM
10
and TM
01
modes is also presented in
Kwai et al. paper. The authors first obtained the electric
field under the curved patch using the cavity model and
then calculated the far field by considering the equivalent
magnetic current radiating in the presence of cylindrical
surface. The cavity model, used for the analysis is only
valid for a very thin dielectric. Also, for much small
thickness than a wavelength and the radius of curvature,
only TM modes are assumed to exist. In order to calculate
the radiation patterns of cylindrical-rectangular patch
antenna. The authors introduced the exact Green’s function
approach. Using Equation (4), they obtained expressions for
the far zone electric field components E
and E
as a func-
tions of Hankel function of the second kind H
p
(2)
. The input
impedance and Q factors are also calculated under the same
h
W

L

conditions.
Based on cavity model, microstrip conformal antenna on a
projectile for GPS (Global Positioning System) device is
designed and implemented by using perturbation theory is
introduced by Sun L., Zhu J., Zhang H. and Peng X [13].
The designed antenna is emulated and analyzed by IE3D
software. The emulated results showed that the antenna
could provide excellent circular hemisphere beam, better
wide-angle circular polarization and better impedance
match peculiarity.
Nickolai Zhelev introduced a design of a small conformal
microstrip GPS patch antenna [14]. A cavity model and
transmission line model are used to find the initial
dimensions of the antenna and then electromagnetic
simulation of the antenna model using software called
FEKO is applied. The antenna is experimentally tested and
the author compared the result with the software results.
It was founded that the resonance frequency of the
conformal antenna is shifted toward higher frequencies
compared to the flat one.
The effect of curvature on a fringing field and on the
resonance frequency of the microstrip printed antenna is
studied in [15]. Also, the effect of curvature on the
performance of a microstrip antenna as a function of
temperature for TM
01
and TM
10
is introduced in [16], [17].
3. General Expressions for Electric and
Magnetic Fields Intensities
In this section, we will introduce the general expressions of
electric and magnetic field intensities for a microstrip
antenna printed on a cylindrical body represented in
cylindrical coordinates.
Starting from Maxwell’s Equations, we can get the relation
between electric field intensity E and magnetic flux density
B as known by Faraday’s law [18], as shown in
Equation (2):
(2)
Magnetic field intensity H and electric flux density D are
related by Ampérés law as in Equation (3):
(3)
where J is the electric current density.
The magnetic flux density B and electric flux density D as a
function of time t can be written as in Equation (4):
and (4)
where is the magnetic permeability and is the electric
permittivity.
By substituting Equation (4) in Equations (2) and (3), we
can get:
and (5)
where is the angular frequency and has the form of:
. In homogeneous medium, the divergence of
Equation (2) is:
and (6)
From Equation (5), we can get Equation (7):
or (7)
Using the fact that, any curl free vector is the gradient of the
same scalar, hence:
(8)
where is the electric scalar potential.
By letting:
where A is the magnetic vector potential.
So, the Helmholtz Equation takes the form of (9):
A+ -J (9)
k is the wave number and has the form of: , and
is Laplacian operator. The solutions of Helmholtz
Equation are called wave potentials:
(10)
3.1 Near Field Equations
By using the Equations number (10) and magnetic vector
potential in [19], we can get the near electric and magnetic
fields as shown below:
(12)
E
and E
are also getting using Equation (7);
(13)
(14)
To get the magnetic field in all directions, we can use the
second part of Equation (10) as shown below, where H
z
= 0
for TM mode:
(15)
(16)
3.2 Far Field Equations
In case of far field, we need to represent the electric and
magnetic field in terms of r, where r is the distance from the
center to the point that we need to calculate the field on it.
By using the cylindrical coordinate Equations, one can
notice that a far field tends to infinity when r, in Cartesian
coordinate, tends to infinity. Also, using simple vector
analysis, one can note that, the value of k
z
will equal to
[19], and from the characteristics of Hankel
function, we can rewrite the magnetic vector potential
illustrated in Equation (12) to take the form of far field as
illustrated in Equation (17).
(17)
Hence, the electric and magnetic field can easily be
calculated as shown below:
(18)
(19)
(20)
The magnetic field intensity also obtained as shown below,
where H
z
= 0:
(21)
(22)
4. Quality Factor, Gain, and
Efficiency
Quality factor, gain, and efficiency are antenna fig-
ures-of-merit, which are interrelated, and there is no com-
plete freedom to independently optimize each one [7].
4.1 Quality Factor
The quality factor is a figure-of-merit that is representative
of the antenna losses. Typically there are radiation, conduc-
tion, dielectric and surface wave losses. Therefore the total
quality factor Q
t
is influenced by all of these losses and is
written as:


(23)
where
Q
t
= total quality factor
Q
rad
= quality factor due to radiation (space wave) losses
Q
c
= quality factor due to conduction (ohmic) losses
Q
d
= quality factor due to dielectric losses
Q
sw
= quality factor due to surface wave losses
Q for any of the quantity on the right-hand side can be rep-
resented as:


(24)
where, the stored energy at resonance W
T
is the same,
independent of the mechanism of power loss. Therefore,
Equation (23) can be expressed as:





(25)
The stored energy is determined by the field under the patch,
and is expressed as [20]:

 (26)
We can get the electric field under the patch using Equation
(14):






  



(27)
So the total energy stored is determined by substitute
Equation (27) in Equation (26) as follow:





 




  (28)
By solving this Equation, one can get the following:


 



 
 



 
 (29)
The dielectric loss is calculated from the dielectric field
under the patch as in [20]:



 (30)
or as a function of total energy as:

(31)
where  is the loss tangent of the dielectric material. So;
the dielectric loss is calculated using Equations (29) and
(31). The power loss due to the conduction is calculated
from the magnetic field on the patch metallization and
ground plate,


 (32)
where R
s
is the surface resistivity of the conductors given
by
 and σ is the conductivity of the conductor. By
using the approximation in [19] for the electric and magnetic
field
, and by using the height equal to h, one can
get the following approximate Equation:


(33)
For very thin substrate, which is the case, the losses due to
surface wave are very small and can be neglected [7]. The
power radiated from the patch P
r
can be determined by in-
tegrating the radiation field over the hemisphere above the
patch. This is,




(34)
By using Equations (13)-(14), we can get an expression for
E
and E
as shown below:







(35)









(36)
Now the radiated power will take the form:














 





(37)
4.2 Antenna Gain
The gain is the ratio of the output power for an an-
tenna to the total input power to the antenna. The input
power to the antenna is the total power including, radiated
power and the overall losses power. So, the gain can be
represented as follows:




(38)
4.3 Antenna Efficiency
Antenna efficiency is defined as the ratio of the total radi-
ated power to the total input power. The input power to the
antenna is the total power including, radiated power and the
overall losses power. So, the gain can be represented as
follows:




(39)
The total input power includes the power lost due to con-
duction, dielectric and surface wave losses and the radiated
power from the antenna.
5. Results
For the range of GHz, the dominant mode is TM
10
for
h<<W which is the case. Also, for the antenna operates at
the ranges 2.49, 2.24 and 1.11 GHz for three different
substrates we can use the following dimensions; the original
length is 41.5 cm, the width is 50 cm and for different lossy
substrate we can get the effect of curvature on the effective
dielectric constant and the resonance frequency.
Three different substrate materials RT/duroid-5880 PTFE,
K-6098 Teflon/Glass and Epsilam-10 ceramic-filled Teflon
are used for verifying the new model. The dielectric
constants for the used materials are 2.2, 2.5 and 10
respectively with a tangent loss 0.0015, 0.002 and 0.004
respectively.
5.1 RT/duroid-5880 PTFE Substrate
The mathematical and experimental results for input im-
pedance, real and imaginary parts, VSWR and return loss
for a different radius of curvatures are given in [15].
Normalized electric field for different radius of curvatures
is illustrated in Figure 5. Normalized electric field is plotted
for from zero to and equal to zero. As the radius of
curvature is decreasing, the radiated electric field is getting
wider, so electric field at 20 mm radius of curvature is wider
than 65 mm and 65 mm is wider than flat antenna. Electric
field strength is increasing with decreasing the radius of
curvature, because a magnitude value of the electric field is
depending on the effective dielectric constant and the
effective dielectric constant depending on the radius of
curvature which decreases with increasing the radius of
curvature.
Normalized magnetic field is wider than normalized electric
field, and also, it is increasing with deceasing radius of
curvature. Obtained results are at for from zero to and
equal to zero and for radius of curvature 20, 65 mm and
for a flat microstrip printed antenna are shown in Figure 6.
For different radius of curvature, the resonance frequency
changes according to the change in curvature, so the given
normalized electric and magnetic fields are calculated for
different resonance frequency according to radius of
curvatures.
Figure 5. Normalized electric field for radius of curvatures 20, 65 mm and
a flat antenna at θ=0:2π and φ=0
0
.
Figure 6. Normalized magnetic field for radius of curvatures 20, 65 mm
and a flat antenna at θ=0:2π and φ=0
0
.
Table 1 shows the resonance frequency, quality factor,
efficiency, and gain for TM
10
mode. The efficiency is
increased with increasing curvature to be 96.55% at radius
of curvature 10 mm. The same behavior for the gain with
radius of curvature, the gain is 9.3 dB at radius of curvature
10 mm. Increasing the quality factor with decreasing the
curvature is due to the decreasing of the radiated power
from the antenna. So, the efficiency will decreased with
increasing the quality factor, due to decreasing in the
radiated power, and the same for the gain.
Table 1. Resonance frequency, quality factor, efficiency, and gain for TM
10
for RT/duroid-5880 PTFE substrate
R
f
r
(GHz)
Q
tot
η
G(dB)
Flat
2.4962
1282.27
92.24
4.11
200 mm
2.4957
1281.902
95.07
7.82
50 mm
2.4945
1281.622
95.73
8.59
10 mm
2.4892
1281.149
96.556
9.3
5.2 K-6098 Teflon/Glass Substrate
The normalized electric field for K-6098 Teflon/Glass
substrate is given in Figure 7 at different radius of
curvatures 20, 65 mm and for a flat microstrip printed
antenna.
Normalized electric field is calculated at equal to values
from zero to and equal to zero. At radius of curvature
20 mm, the radiation pattern of normalized electric field is
wider than 65 mm and flat antenna, radiation pattern angle
is almost 120
0
, and gives a high value of electric field
strength due to effective dielectric constant.
The normalized magnetic field is given in Figure 8, for the
same conditions of normalized electric field. Normalized
magnetic field is wider than normalized electric field for
20 mm radius of curvature; it is almost 170
0
for 20 mm
radius of curvature. So, for normalized electric and
magnetic fields, the angle of transmission is increased as a
radius of curvature decreased.
Figure 7. Normalized electric field for radius of curvatures 20, 65 mm and
a flat antenna at θ=0:2π and φ=0
0
.
Figure 8. Normalized magnetic field for radius of curvatures 20, 65 mm
and a flat antenna at θ=0:2π and φ=0
0
.
As in Table 2, the resonance frequency is increased with
decreasing the curvature of microstrip printed antenna. The
total quality factor is increased by a small value for radius
of curvature 10, 50, and 200 mm. The efficiency and gain
are increased with increasing radius of curvature.
Table 2. Resonance frequency, quality factor, efficiency, and gain for TM
10
for K-6098 Teflon/Glass substrate
R
f
r
(GHz)
Q
tot
η
G(dB)
Flat
2.2404
1083.124
90.03
5.81
200 mm
2.2400
1082.8879
90.77
5.97
50 mm
2.2390
1082.76799
95.66
8.82
10 mm
2.2345
1082.348
96.169
9.3
5.3 Epsilam-10 Ceramic-Filled Teflon
Normalized electric field for different radius of curvatures
is illustrated in Figure 9. Normalized electric field is plotted
for from zero to and equal to zero. As the radius of
curvature is decreasing, the radiated electric field is getting
wider, so electric field at 20 mm radius of curvature is wider
than 65 mm and 65 mm is wider than flat antenna. Electric
field strength is increasing with decreasing the radius of
curvature, because a magnitude value of the electric field is
depending on the effective dielectric constant and the
effective dielectric constant depending on the radius of
curvature which decreases with increasing the radius of
curvature.
Normalized magnetic field is wider than normalized electric
field, and also, it is increasing with deceasing radius of
curvature. Obtained results are at for from zero to 2π and
equal to zero and for radius of curvature 20, 65 mm and
for a flat microstrip printed antenna are shown in Figure 10.
For different radius of curvature, the resonance frequency
changes according to the change in curvature, so the given
normalized electric and magnetic fields are calculated for
different resonance frequency according to radius of
curvatures.
Figure 9. Normalized electric field for radius of curvatures 20, 65 mm and
a flat antenna at θ=0:2π and φ=0
0
.
Figure 10. Normalized magnetic field for radius of curvatures 20, 65 mm
and a flat antenna at θ=0:2π and φ=0
0
.
Table 3 shows the resonance frequency, quality factor,
efficiency, and gain for TM
10
mode. The efficiency is
increased with increasing the radius of curvature. The gain
has the same behavior for decreasing radius of curvature.
Table 3. Resonance frequency, quality factor, efficiency, and gain for TM
10
for Epsilam-10 ceramic-filled Teflon substrate
R
f
r
(GHz)
Q
tot
η
G(dB)
Flat
1.1149
663.795
86.739
4.81
200 mm
1.1148
663.3924
88.122
5.97
50 mm
1.1143
663.27789
90.758
8.59
10 mm
1.1126
661.3518
92.92
9.3
6. Conclusion
The effect of curvature on the performance of conformal
microstrip antenna on cylindrical bodies for TM
10
mode is
studied in this paper. Curvature affects the fringing field and
fringing field affects the antenna parameters. The Equations
for resonance frequency, gain, efficiency and quality factor
as a function of curvature is introduced in this paper. These
parameters are given for TM
10
mode and using three
different substrate materials RT/duroid-5880 PTFE, K-6098
Teflon/Glass and Epsilam-10 ceramic-filled Teflon.
For the three dielectric substrates, the decreasing in
resonance frequency due to increasing in the curvature leads
to decreasing in quality factor and on the other hand, leads
to increasing in the efficiency and the gain of the microstrip
printed antenna. The radiation pattern for electric and
magnetic fields due to increasing in curvature is also
increased and be more wider.
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ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
A temperature is one of the parameters that have a great effect on the performance of microstrip antennas for TM 10 mode at 2.4 GHz frequency range. The effect of temperature on a resonance frequency, input impedance, voltage standing wave ratio, and return loss on the performance of a cylindrical microstrip printed antenna is studied in this paper. The effect of temperature on electric and magnetic fields are also studied. Three different substrate materials RT/duroid-5880 PTFE, K-6098 Teflon/Glass, and Epsilam-10 ceramic-filled Teflon are used for verifying the new model. KEYWORDS Temperature, Voltage Standing Wave Ratio VSWR, Return loss S11, effective dielectric constant, Transverse Magnetic TM 10 model.
Article
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Due to unprinted growth in wireless applications and increasing demand of low cost solutions for RF and microwave communication systems, the microstrip flat antenna, has undergone tremendous growth recently. Though the models to analyze microstrip structures have been widely accepted, effect of curvature on dielectric constant and antenna performance has not been studied in detail. Low profile, low weight, low cost and its ability of conforming to curve surfaces [1], conformal microstrip structures have also witnessed enormous growth in the past few years. Applications of microstrip structures include Unmanned Aerial Vehicle (UAV), planes, rocket, radars and communication industry [2]. Some advantages of conformal
Article
Full-text available
The fringing field has an important effect on the accurate theoretical modeling and performance analysis of microstrip patch antennas. Though, fringing fields effects on the performance of antenna and its resonant frequency have been presented before, effects of curvature on fringing field have not been reported before. The effective dielectric constant is calculated using a conformal mapping technique for a conformal substrate printed on a cylindrical body. Furthermore, the effect of effective dielectric constant on the resonance frequency of the conformal microstrip antenna is also studied. Experimental results are compared to the analytical results for RT/duroid-5880 PTFE substrate material. Three different substrate materials RT/duroid-5880 PTFE, K-6098 Teflon/Glass, and Epsilam-10 ceramic-filled Teflon are used for verifying the new model. KEYWORDS Fringing field, microstrip antenna, effective dielectric constant and Resonance frequency.
Chapter
IntroductionThe ProblemElectrically Small SurfacesElectrically Large SurfacesTwo ExamplesA Comparison of Analysis Methods Appendix 4A—Interpretation of the ray theoryReferences
Book
Foreword to the Revised Edition. Preface. Fundamental Concepts. Introduction to Waves. Some Theorems and Concepts. Plane Wave Functions. Cylindrical Wave Functions. Spherical Wave Functions. Perturbational and Variational Techniques. Microwave Networks. Appendix A: Vector Analysis. Appendix B: Complex Permittivities. Appendix C: Fourier Series and Integrals. Appendix D: Bessel Functions. Appendix E: Legendre Functions. Bibliography. Index.
Chapter
In this chapter we describe the characteristics of cylindrical microstrip antennas excited by a coax feed or through a coupling slot fed by a microstrip feed line. Typical types of rectangular, triangular, circular, and annular-ring microstrip antennas are analyzed. Characterization of curvature effects on the input impedance and radiation characteristics is of major concern. Calculated solutions obtained from various theoretical techniques, such as the full-wave approach, cavity-model analysis, and the generalized transmission-line model (GTLM) theory, are shown and discussed. Some experimental results are also presented for comparison.
Article
Contenido: Campos electromagnéticos, Propiedades eléctricas de la materia; La ecuación de onda y su solución; Polarización y propagación de ondas; Reflexión y trasmisión; Vectores potenciales auxiliares; Principios y teoremas electromagnéticos; Ondas rectilínea y cavidades; Ondas curvas y cavidades; Trasmisión de líneas esféricas y cavidades; Dispersión; Ecuaciones integrales y método de momento; Teoría geométrica de la difracción; Funciones de Green.
Book
This publication is the first comprehensive treatment of conformal antenna arrays from an engineering perspective. There are journal and conference papers that treat the field of conformal antenna arrays, but they are typically theoretical in nature. While providing a thorough foundation in theory, the authors of this publication provide readers with a wealth of hands-on instruction for practical analysis and design of conformal antenna arrays. Thus, readers gain the knowledge they need, alongside the practical know-how to design antennas that are integrated into structures such as an aircraft or a skyscraper. Compared to planar arrays, conformal antennas, which are designed to mold to curved and irregularly shaped surfaces, introduce a new set of problems and challenges. To meet these challenges, the authors provide readers with a thorough understanding of the nature of these antennas and their properties. Then, they set forth the different methods that must be mastered to effectively handle conformal antennas. This publication goes well beyond some of the common issues dealt with in conformal antenna array design into areas that include: Mutual coupling among radiating elements and its effect on the conformal antenna array characteristics Doubly curved surfaces and dielectric covered surfaces that are handled with a high frequency method Explicit formulas for geodesics on surfaces that are more general than the canonical circular cylinder and sphere With specific examples of conformal antenna designs, accompanied by detailed illustrations and photographs, this is a must-have reference for engineers involved in the design and development of conformal antenna arrays. The publication also serves as a text for graduate courses in advanced antennas and antenna systems.
Conference Paper
The work presents a design of a cylindrical conformal phased microstrip antenna array. Based on the HFM and the parallel feed network, a conformal microstrip 2 times 8 array on a cylinder surface is designed by the isotropic transformation theory (IT). Simulation results show that the conformal array works at 35GHz and the gain is 19.6dB at the center frequency. The phase-scanned patterns of the conformal 2 times 8 array are analyzed by the CST using phase control method. From the comparison of the scanning results at different phase division, it can be found that the scan angle, the angular width and the side lobe level varies following the trends of the phase division, at the same time, the gain of the conformal array changes markedly opposite the trends of the phase division. Therefore, this is a shortcoming of the conformal phased array. This kind of conformal phased sub-array can be easily expanded into a large-scale conformal array and be suitable for active integration with other microwave circuits and communication systems if this disadvantage was eliminated after further discussion in future.
Conference Paper
The conformal FDTD algorithm is employed to analyze the characteristics of the probe-fed conically conformal microstrip patch antenna. The non-uniform meshing technique in Cartesian coordinate system is used. The numerical results show that the conformal algorithm is efficient and accurate enough, besides its better adaptability in dealing with arbitrary antenna structures and shapes.