Design and optimization a circular shape [601319]

Design and optimization a circular shape
network antenna MIMO OFDM 8X8
technol ogy Micro strip

Louati siwar1, [anonimizat]
fathi mejri 2, fethi mejri @laposte.net

Abstract – In this article we have designed a network of
antenna that consists of eight circular antennas micro strip we
work at 2.4GHz frequency with a bandwidth of 20MHz several
characteristics of the antenna as return directivity, bandwidth
percentage ,radiation pattern ,loss ,antenna gain ,radiation
efficiency are studied
.

Keywords – Technology MIMO -OFDM ,micro strip
,microwave ,antenna technology

I. INTRODUCTION
Wireless telecommunication has experienced many changes
lately. A traditional telephony was added many services such as
internet, video conferencing, the visualization of films and many
others These services could be availed on our mobiles than ks to
an evolution of technology .but quickly a debit or scope problem
is presented a new technique appeared in 1984 thanks to Mr.
.jack winters, who filed a patent for wireless communication to
multiple antennas [2]Since this discovery ,this system has be en
very used in servel areas these of multiple antennas to the
emission and reception in radio systems is one of the most
important advances developed last times .they allow to reduce
the likelihood of error and to increase the transmission rate
without in creasing power transmission or used bandwidth
.however ,the majority of studies are too theoretical , and
currently are there are few rigs to check the viability of these
techniques in real transmission conditions and get a more
realistic assessment of the performance of the system In recent
developments in telecommunications ,the multiple technology
uses spatial diversity .it was already this principle on the Wi -Fi
systems legacy the addition of receiver antennas allowed for
example to make a selection of the antenna on a criterion of
power to take micro strip antennas deep applications especially
in the filed mobile military , medical and telecommunication
satellite their use has become diverse because of their small size
and its lightness .Manufacturing r apid and cost effective is
particularly important when it comes to prototyping of antennas for their evolution of the performance . as wireless applications
require more and more bandwidth ,the demand for large antennas
broadband operating at higher frequ encies ,it becomes inevitable
.inherently micro strip antenna have narrow bandwidth and low
efficiency and their performance greatly depends on the
parameters of substrate that is it dielectric constant ,uniformity ,
and loss tangent [5].in this article ,w e designed a circular micro
strip antenna operating at frequency of 2.4GHz .the antenna is
designed on a Teflon substrate glass having a constant dielectric
εr=4.32 and the height of the substrate h=1.5mm.A copper
ground conductor is used with equal conduc tivity5.96×106
siemens /m and by a thickness T=35µm and has modeled loss
equal to 0.0019 circular antenna is made and black fly using
software ADS

II. DESIGN OF AN ANTENNA

The antenna represent an important component of the chain of
transmission since it af fects the transmission and reception of the
signal radiated in free space the choice of type of antenna
depends on type of network of covered area and emission levels
to do this you choose a circular antenna.
The micro strip structure that we used has a dr iver in copper
characterized by a conductivity ζ = 58, 5.106 (S/m) and a
thickness T = 35µm. the substrate is glass Teflon of relative
permittivity εr = 4.32 thickness H = 1, 5 mm and has losses
modeled by tgδ = 0, 0019.was used ADS as a software
Simulatio n of an antenna We used as software ADS as a
simulation software

A. Design of an antenna and simulation:
Now turn to the study of the radiating element that we will study
has a length L1= λ/2 = 17 mm Determined by lincalc.an antenna
is connected to the source by a line shift wave impedance
characteristic Z'c = √ (Ze * Z0) and length of λ/4 or Ze the input

impedance of the antenna .and a raw of characteristic impedance
Z0 = 50 Ohm including its length L3=10mm and its width
W3=2.86mm .Adaptation impedance allows to cancel of the
coefficient of reflection in the antenna input .the reflection
coefficient is the ratio be tween the wave reflected input the
antenna and the incident wave. The structure of the
antenna under MOMENTUM is represented by figure using the
dimensions calculated in Line Calc

Figure1: Antenna under MOMENTUM

Under schematic , we bring the antenna c reates in order to
optimize length of line transmission used on the frequency
interval [2 GHz, 3 GHz].to do this ,we define the lower interval
of optimization for the length as well as the coefficient of
reflection S11under schematic at -20dB .
After op timization, we get the following values: L1=
17.02 mm of circular antenna L2 = 18.62 mm w2 = 0.198 mm L3
= 10 mm and W3 = 2.86 mm
.
B. Design of antenna network and simulation:
No after the frist antenna design was complted other antennas
similarly except that by changing the frequency of work .the end
of all antennas, we turn to the creation network antenna working
in 2.4GHz maximum bandwidth of 20MHz
.

IV. SIMULATION RESULTS AND Discussions :
A. simulation an antenna:
After a simulation, we notice that the antenna is well suited
since we have an attenuation of -24.518dB
Which is la lower value strictly at -20dB and represents a
minimum reflection of the signal .we find also an impedance
value equal 56.223Ohm for 2.4GHz frequency .these results are
shown in figure 3 Which shows that almost a perfect feed
configuration is reseached,i,e Figure3: results of
simulation of antenna under MOMENTUM (re
al (Z), image (Z), phase (Z), S11 (dB))

Here this is the of the frist ant enna frequency 2.412GHz is
carried out by our reffecient toolADS, subsequently for other
antennas that it was decided to follow the same approach already
followed .the design of these antennas is done to investigate the
effect of coupling and directivity o f these antennas at the location
in a common environment since we are trying to build a network
of antennas composed by 8 antennas to increase the flow in the
transmission and reception of data .
For this we ‘ell represent deferens characteristics of frist antenna
that helps us identify the type of radiation .simulation software
used to plot ,simulate and predict the characteristics of âtch
antenna is ADS advanced Design system which and thanks to its
tool Momentum allows an electromagnetic simulation based on
grid finite Element of the patch and presents the values of gain
and directivity and radiation in two and three dimensions

Figure 5: Resultant of analyzer

From this curve we note that the frequency of resonance for this
antenna is just the same as for ADS and more is adapted has the
frequency 2.412GHz S (11) = -14 dB, where the result is sought.
Later we realize the comparison and this is what we find:

(a)

(b)

Figure:4 : radiation pattern (front view(a),
(rear view(b))

the figure represents the first antenna radiation pattern ,it
indicates that this circular antenna is directivity .it connects our
first antenna network analyser on us ing a single port , onuses the
matter it retrieve the resultat of S11to compare it with the result
at that was found by ADS.
In this part and after the completion of measures drawing the repr
esentative gain curve S (11) and then compared with that of the
ADS. This is the result that was found

Figure 7: comparative curve
This curve there that measurements made by the network for this
antenna Analyzer are accurate so our work done by ADS
(Advanced Design System) is compatible with the measures
carried out for this one provides a validation of work.

C. Simulation software of antennas network

Figure 10:resultat of network antennas

Figure 8:

Figure 9: resultat of analzer

As shown in the previous figure on extract two our network
MIMO antennas and one realizes measures as was done for the fi
rst antenna, subsequently comparing its results with those found
by the ADS.
Include the following lines:
From these representative curves of measures found by the
parser we note that ADS
gives good results, for this reason we valid this work and we fin
ish our designs only with this tool
Deferens steps to achieve a suitable antenna design was studied i
n this article and function in
a just manner has a specific frequency, and these steps are the sa
me that
we follow when we will determine other antennas except that it c
hanges the frequency of work from one to the
other, then completed the measures for the first antenna
that was alread y prepared by theADS and the validation of the la
-tter were assured.
Subsequently measured MIMO network by the Network Analyze
r and compared theresults found with that it has already carried
out by our software, and end of this comparison it concludes that
this design is valid

V. CONCLUSION
in n this paper, we have presented the design and simulation of a
Circular Microstrip patch Antenna at c band freque ncy region.
The simulated results of circular microstrip patch antenna shows
good directivity and gain value. The directivity and gain for the
circular patch antenna is 4.5dBi and 2.66dBi respectively and a
percentage bandwidth achieved is 3.79%. The high return loss
value gives perfect impedance matching between patch and feed.
Also, designed circular patch antenna gives a radiation effiiency
equal to 59.1%. However, we can also improve the antenna
characteristics using different known technologies to incr ese the
applicability of this patch antenna. Although, this circular patch
antenna may fid applications satellite comunication
applications such as transponders

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