IJEEE, Vol. 1, Spl. Issue 1 (March 2014)
e-ISSN: 1694-2310 | p-ISSN: 1694-2426
Analyzing the Different Parameters of
Dipole Antenna
1
Amandeep Bath, 2Abhishek Thakur, 3Jitender Sharma , 4Prof. Basudeo Prasad
1,2,3,4
Electronics & Communication Engineering Department,
Indo Global College of Engineering, Punjab, India
1
amandeep_batth@rediffmail.com, 2abhithakur25@gmail.com, 3er_jitender2007@yahoo.co.in
Abstract- Ultra wideband is a wireless technology to
realize high speed communications which is performed in
wideband. In this paper the wideband dipole antenna is
designed. The simulation is done using ANSOFT HFSS
simulation software.
Index Terms- Broad band, wide beam, circular
polarization, conducting wall, micro strip antenna, WideBand, Omni directional radiation pattern smart grid, Wi Max
directive antennas, UWB antennas, Biotelemetry, capsule
endoscope, dipole antenna ,planar reflector antenna.
I. INTRODUCTION
In radio and telecommunications a dipole antenna also
known as doublet is the easiest and most commonly used
class of antenna. It is made up of two similar conductive
elements such as metal wires or rods which are generally
bilaterally symmetrical. The driving current from the
transmitter is given, or for receiving antennas the output
signal to the receiver is obtained and taken, between the two
halves of the antenna. Each side of the feedline to the
transmitter or receiver is joined to one of the conductors. This
is different with a monopole antenna, which is made up of a
single rod or conductor with one side of the feed line joined
to it, and the other side connected to some type of ground.
The best example of a dipole is the "rabbit ears" television
antenna which is found on broadcast television sets.
The most common type of dipole is two straight rods or wires
which are connected end to end on the same axis, with the
feed line connected to the two adjacent ends. This is the
easiest type of antenna from a theoretical point of view.
Dipoles are resonating antennas, meaning that the elements
serve as resonating elements, with standing waves of radio
current which flows back and forth between their ends. So the
length of the dipole elements is calculated by the wavelength
of the radio waves used. The most common type is the one
half wave dipole, in which both of the two rod elements is
approximately 1/4 wavelength long, so the complete antenna
is a half-wavelength long. Numerous different types of the
dipole are also used, such as the folded dipole, short dipole,
cage dipole, bow-tie, and batwing antenna. Dipoles may be
used as standalone antennas themselves, but they are also
used as feed antennas (driven elements) in many more
advanced antenna types, such as the Yagi antenna, parabolic
antenna, reflective array, turnstile antenna, log periodic
antenna, and phased array. The dipole was the oldest and
primitive type of antenna; it was invented by German scientist
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Heinrich Hertz around 1886 in his advanced research of radio
waves
A dipole is a symmetrical antenna, as it is composed of
two symmetrical ungrounded elements. Therefore it works
best when fed by a balanced transmission line, such as a
ladder line. It happens because in that case the symmetry (one
aspect of the impedance complex, which is a complex
number) matches and therefore the power transfer is external.
When a dipole with an unbalanced feed line such as coaxial
cable which is generally used for transmitting the signal, the
shield side of the cable, in addition to the antenna, radiates.
RF currents are induced into other electronic equipment very
close to the radiating feed line, producing RF interference.
Furthermore, the efficiency of the antenna is very low
because it is radiating closer to the ground and its radiation as
well as the reception pattern may be asymmetrically distorted.
At very high frequencies, where the coax diameter is
generally more than the length of the dipole, this becomes a
more prominent problem. To remove this, dipoles fed by
coaxial cables have a balloon kind of structure between the
cable and the antenna, the unbalanced signal provided by the
coax is converted to a very balanced symmetrical signal for
the antenna.
Agile reconfigurable antennas for future communication
systems have attracted researchers around the globe.
Antenna's characteristics such as frequency, radiation pattern
and polarization are reconfigured to attain the demands for
agile radios. A lot of researches focus on frequency
reconfiguration as future communication systems such as
cognitive radio needs an antenna that can do spectrum sensing
and communication. In reconfigurable frequency antennas
development, recently a reconfigurable wide-band to agile
narrow frequencies, using a printed log periodic dipole array
antenna, was introduced. A wideband slotted multifunctional
reconfigurable frequency antenna for WLAN, WIMAX,
UWB and UMTS has been proposed in, a frequency
reconfigurable antenna, consisting of two structures; one is an
ultra-wide band (UWB) and other is a frequency
reconfigurable triangle shape antenna, is proposed for
cognitive radio communication
Ultra-wide band antennas have already been used in
areas such as satellite communication, remote sensing, and
ultra-wide band radar and so on. Currently, the wireless area
network (WLAN) in the 2.4-GHz (2.4-2.485 GHz) and 5-GHz
(5.l5-5.875 GHz) bands is the most popular networks for
accessing the internet the antenna for an AP not only requires
dual-band operation but also needs to have an appropriate
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radiation profile in both bands, namely similar gain, wide
beam width, and high front-to-back ratio. Wireless
communications continues to enjoy exponential growth in
Industrial, Scientific, and Medical (ISM) band. The future
generation wireless networks require systems with broadband capabilities in various environments to satisfy several
applications as smart grid, personal communications, home,
car, and office networking .On the other hand, many modern
wireless communication systems such as radar, navigation,
satellite, and mobile applications use the circular polarized
(CP) radiation pattern. For the best UWB performance, the
transmitter and receiver (T/R) antennas should have flat and
high directive gain, narrow beam, low side and back lobes
over the operational frequency band; to attain the largest
dynamic range, best focused illumination area, lowest T/R
coupling, reduced ringing and uniformly shaped impulse
radiation.UWB has promised to offer high data rates at short
distances with low power, primarily due to wide resolution
bandwidth.
II. ANTENNA DESIGN AND CONFIGURATION
All The geometry and configuration of the proposed
antenna is shown in the figure. Initially the design properties
are selected by adjusting the local variables such as the
substrate height „l=25cm' and the radius 'a=0.5mm' and the
position as well. As shown in the figure the proposed antenna
consists of a cylindrical radiating substrate which is duplicate
d around the X axis with a rectangular lumped port excitation
between them. The duplicated substrate cylindrical antenna
element around the X axis is shown in the figure.
excitation with a position 0,-.5,-2. The the integrating line is
drawn between the cylindrical substrates through the
rectangular element.
Fig. 3: Integrating line between the substrates
The structure is then covered by a vacuum box with the
position -100,-75,-75 mm and the other dimensions as X=200,
Y=150, Z=150mm. Also the transparency is adjusted as 0.76.
Further the faces of the vacuum box are individually selected
for assigning the radiation boundary. Before the final
validation check the solution frequency is adjusted as 300
MHz for the setup. Also for the same set up the frequency
sweep is adjusted by keeping the sweep type as fast and the
start and stop frequencies as 100 and 500Mhz respectively by
keeping the count as linear. Finally the design undergoes the
validation check for the errors.
Fig. 4: Air box over the dipole
Fig. 1: Duplicated cylindrical substrate around the axis
III. DIPOLE CHARACTERISTICS
A. Frequency versus length
Fig. 2: Rectangular radiating element between substrates
The material of the substrate is kept as pec with a bulk
conductivity of 1e+030 Siemens/m. The rectangular element
between the cylindrical substrates provides the lumped
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Dipoles that are very small even smaller than the
wavelength of the signal are called Hertz an, short, or
infinitesimal dipoles. These have a very low radiation
resistance and a high capacitive reactance, so they are not
very much efficient; though inefficient, they can be practical
antennas for long wavelengths. Dipoles whose length is half
the wavelength of the signal are called half-wave dipoles, and
are more efficient. In general radio engineering, the term
dipole usually means a half-wave dipole (center-fed).A halfwave dipole is cut to length l for frequency f in hertz
according to the formula
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Where λd is the wavelength on the dipole elements, λ0 is
the free-space wavelength, c is the speed of light in free space
(299,792,458 meters per second (983,571,060 ft/s)), and k is
called adjustment factor. The adjustment factor completely
compensates for propagation speed being somewhat less than
the speed of light. The dipole elements will have distributed
inductance and capacitance. The value of k is around 0.95.
For thin wires with the dimensions (radius = 0.000001
wavelengths), k is approximately 0.981; for thick wires
(radius = 0.01 wavelengths), k drops to about 0.915.The
above formula which is given is often shortened to the length
in meters = 143/MHz or the length in feet = 468/MHz; MHz is
the frequency in megahertz.
where r is the distance from the doublet to the point
where the fields are evaluated, k = 2π/λ is the wave number,
and Z = √μ/ε = 1/εc = μc is the wave impedance of the
surrounding medium (usually air or vacuum) and the
concerned equations are also shown .The energy associated
with the term of the near field flows alternately out of and
back into the antenna. The exponent of e accounts for the
phase dependence of the electric field on time and the
distance from the dipole. Often one is interested in the
antenna's radiation pattern only in the far field, when
r ≫ λ/2π. In this regime, only the 1/r term contributes, and
hence. The concerned equations are
A. Elementary doublet
From a theoretical point of view, the dipole antenna is the
simplest antenna. An elementary doublet or Hertzian dipole as
shown in the figure is a small length of conductor δℓ (small
compared to the wavelength λ) carrying an alternating current
whose equation is:
The far electric field, Eθ, of the electromagnetic wave is
co-planar with the conductor and perpendicular with the line
joining the dipole to the point where the field is calculated. If
the dipole were placed in the center of a sphere with the axis
south-north, the electric field would be parallel to geographic
meridians and the magnetic field of the electromagnetic wave
would be parallel to geographic parallels
B. Dipole antenna techniques
Fig. 5: Elementary doublet.
Here ω = 2πf is the angular frequency (and f the
frequency), and i = √−1 is the imaginary unit, so that I is a
phasor. It is used in, for example, analytical calculation on
more complex antenna geometries. Note that physical
construction of the dipole is difficult because the current
needs somewhere to come from and somewhere to go to.
Actually, this small length of conductor will be just one of the
multiple segments into which we must divide a real antenna,
in order to calculate its properties. In the case of the
elementary doublet which is shown in the figure it is possible
to find exact, closed-form expressions for its electric field, E,
and its magnetic field, H. In spherical coordinates, they are
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Implementation of wideband antenna for smart grid
applications with a frequency bandwidth of 40% and gain of 3
to 4dbThe antenna design and simulation was carried out
using ANSYS‟ HFSS software which is the industry-standard
simulation tool for 3-D full-wave electromagnetic field
simulation. The total size of the antenna is 20mm x 10mm x
2mm. This new design offers a wide fractional frequency
bandwidth of about 40% with a gain from 3dB-4.3dB over the
frequency band (5GHz – 7.5GHz)
Using ultra wideband dipole antenna operating at 1.75 to 40
GHz .It is shown that the proposed antenna works well in
1.7GHz-40GHz frequency range and the main direction of the
radiation pattern keeps stable during the whole frequency
range. The H plane demonstrates an excellent Omnidirectional pattern.
A Dual-band Wide-beam width WLAN Access Point
Antenna with similar gain and wide beam width in both the
2.4- and 5-GHz WLAN bands. This paper describes a dual
band printed dipole antenna that has nearly identical radiation
patterns with similar gain and wide beam width in both the
2.4- and 5-GHz WLAN bands. The proposed design employs
two techniques to improve the radiation pattern. These
techniques are the use of an angle dipole and vertical copper
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plates arranged on the ground plane for improvement in the
radiation pattern of lower and upper bands, respectively .Ultra
band dipole antenna and circularly polarized antenna provides
the best Omni directional radiation pattern. Also the
techniques such as angled dipole and vertical copper plates on
ground plane are used for the further improvement of the
radiation pattern of the antenna.
IV. RESULTS AND DISCUSSION
In this section the lambda /2 dipole antenna is
constructed and the numerical and experimental results
regarding the radiation characteristics are presented and
discussed. The simulated results are obtained by using the An
soft simulation software high frequency structure simulator.
The measured and simulated characteristics of the antenna are
shown and from the far field report the rectangular plot, the
3D polar plot and are drawn and the radiation characteristics
are also plotted.
Fig. 8: Radiation Pattern
Next the radiation pattern for a half wave dipole antenna is
shown along with the stacked XY plot
Fig. 9: XY stacked plot
Fig. 6: XY Rectangular Plot
Fig. 10: Electric fields (blue) and magnetic fields (red) radiated by a
dipole antenna
Fig. 7: 3D Polar Plot
Unlike other antennas reported in the literature to date, the
proposed antenna displays a good omnidirectional radiation
pattern even at higher frequencies. The designed antenna has
a small size and good return loss and radiation pattern
characteristics are obtained in the frequency band of interest.
The simulated and experimental results show that the
proposed antenna could be a good candidate for UWB
applications. The radiation pattern is shown in the figure for
the dipole antenna.
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A. Radiation Pattern and Gain
Dipoles have a radiation pattern, shaped like a toroids
(doughnut) symmetrical about the axis of the dipole. The
radiation is maximum at right angles to the dipole, dropping
off to zero on the antenna's axis. The theoretical maximum
gain of a Hertzian dipole is 10 log 1.5 or 1.76 dBi. The
maximum theoretical gain of a λ/2-dipole is 10 log 1.64 or
2.15 dBi.
V.
CONCLUSION AND FUTURE WORK
With the rapid progress of wireless technology in recent
years, various wireless systems such as GSM,
WCDMA/UMTS, Bluetooth, WLANs, and GPS have been
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highly integrated into the mobile devices, and in order to
fulfill the RF system requirements using the different
frequency band, antenna technology is required to wideband
characteristics .On the other hand, many modern wireless
communication systems such as radar, navigation, satellite,
and mobile applications use the circular polarized (CP)
radiation pattern. The attractive advantages of the CP antenna
are existed as follows. Firstly, since the CP antennas send and
receive in all planes, it is strong for the reflection and
absorption of the radio signal. In the multi-path fading
channel environment, the CP antenna overcomes out of phase
problem which can cause dead-spots, decreased throughput,
reduced overall system performance. Additionally. Also
further improvements could be done by using antenna
substrates with higher dielectric constants in order to reduce
the size a broad band wide beam circular polarization micro
strip antenna. The configuration of the antenna is simple and
easy to fabricate compared with conventional micro strip
antenna, the radiation beam is broadened obviously. Further
research on circularly polarized wideband
micro strip
antenna is required as it gives the best performance and
overall improvement of antenna parameters.
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AUTHORS
First Author – Amandeep Batth:
M. Tech. in Electronics and
Communication Engineering from
Punjab Technical University, MBA
in Human Resource Management
from Punjab Technical University ,
Bachelor in Technology (B-Tech.)
from Punjab Technical University .
Six years of work experience in
teaching. Area of interest: Antenna
Design and Wireless Communication. International
Publication: 1, National Conferences and Publication: 4.
Working with Indo Global College of Engineering Abhipur,
Mohali, P.B. since 2008.
Email: amandeep_batth@rediffmail.com
Second Author– Abhishek Thakur:
M. Tech. in Electronics and
Communication Engineering from
Punjab Technical University, MBA
in Information Technology from
Symbiosis Pune, M.H. Bachelor in
Engineering (B.E.- Electronics)
from Shivaji University Kolhapur,
M.H. Five years of work experience
in teaching and one year of work
experience in industry. Area of interest: Digital Image and
Speech Processing, Antenna Design and Wireless
Communication. International Publication: 7, National
Conferences and Publication: 6, Book Published: 4
(Microprocessor and Assembly Language Programming,
Microprocessor and Microcontroller, Digital Communication
and Wireless Communication). Working with Indo Global
College of Engineering Abhipur, Mohali, P.B. since 2011.
Email: abhithakur25@gmail.com
Third Author – Jitender Sharma: M. Tech. in Electronics and
Communication Engineering from Mullana University,
Ambala, Bachelor in Technology (B-Tech.)from Punjab
Technical University . Five years of work experience in
teaching. Area of interest:, Antenna Design and Wireless
Communication. International Publication: 1 National
Conferences
and
Publication:6
and
Wireless
Communication). Working with Indo Global college since
2008.
E-mail:er_jitender2007@yahoo.in
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