Design and Development of Linearly Polarized Patch Antenna of Circular Shape for Lower UWB Band

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 2236
DESIGN AND DEVELOPMENT OF LINEARLY POLARIZED PATCH
ANTENNA OF CIRCULAR SHAPE FOR LOWER UWB
BAND
Amruta Nikam1 Sandhya Shinde. 2
1AsstProf.E&TC Dept ,DYPIEMR,Akurdi Pune-44
2 Asst.Prof E&TC Dept ,DYPIEMR,Akurdi Pune-44
------------------------------------------------------------------------***----------------------------------------------------------------------
Abstract— the paper shows the results for design and
computer simulation for the Ultra-wideband antenna of
WPAN application. It also explains the difference between
narrow band and ultra wide band. The antenna has
excellent performance for lower-band frequency of UWB
system, ranging from 3.1 GHz to 5.1 GHz. Over the entire
frequency band, the antenna has a 10 dB return loss
bandwidth .The antenna is designed on Rogers RT/duroid
5880 substrate and fed with 50 ohms coupled tapered
transmission line. The proposed antenna designs and
performances are examined using Ansoft High Frequency
structure Simulator (HFSS).
Index Terms— UWB, Antenna design, broadband
wireless communication, and WPAN
I. NTRODUCTION
Ultra-wideband (UWB) system is ideal candidate that
can be used for commercial ,small range ,low power ,
cost effective indoor communication system such as
wireless personal area network (WPAN)[1]-[3]. In UWB
communication systems, the antennas are pulse-shaping
filters. Any distortion of the signal in the frequency
domain results to the distortion of the transmitted
pulses shape. Consequently this can increase the
complexity of the detection mechanism at the receiver.
The antenna design for UWB signal radiation is one of
the main challenges. Specially, cost effective,
geometrically small and still important structures are
needed for typical wireless applications such as WPANs.
The UWB technology offers several benefits over
conventional communications systems. For instance,
there is no carrier Frequency. Therefore transmitter and
receiver hardware’s can be made very user friendly,
which is necessary for the portable devices. There is a
wide range of applications for UWB technology, which
includes wireless communication systems, position and
tracking, sensing and imaging, and radar. Antenna plays
an essential role in UWB system, which is different from
narrowband system. UWB systems send very narrow
pulses of the order of 1 ns or fewer results to
bandwidths in excess of 1 GHz or more. But, the design
and construction of high-performance
conveying/acceptance antennas are always present
substantial Challenges in the application of these
systems. The impulse response of the antenna is vital
because it has the affinity to change or shape the
transmitted or received pulses. In run-through, attempt
must be made to limit the amplitude and group delay
misrepresentation below certain threshold that will
ensure consistent system performance. The aim of the
current study is to establish guidance for the UWB
antenna designers, make notes on the required
parameters of UWB antennas, and provide an example of
UWB antenna. The challenge found in the development
of an antenna, capable of handling these high-speed
pulse trains. Because the fractional bandwidth is actually
large hence UWB antenna design is very complicated,
and antenna must cover multiple-octave bandwidths in
order to transmit pulses that are of the order of a
nanosecond in duration. Since data may be contained in
the shape of the UWB pulse, antenna pulse distortion
must be kept to a smaller side.
II REVIEW OF THE STATE-OF-ART:
In the early days of radio the concept of ultra wideband
communication created. In the 1900s, the Marconi spark
gap transmitter (the beginning of radio) communicated
by spreading a signal over a very wide bandwidth. For
distribution this use of spectrum did not permit, so the
communications world sudden wideband
communication in favor of narrowband or tuned
communication in which the FCC governed spectrum
allocation. The FCC provides guidelines for radiated
power in the bandwidths of these communications
systems and for incidental out of band radiated power.
This incidental radiated power limits were the
motivation for various organizations to challenge the
paradigm of narrowband communications, in an ongoing
effort to grab the capacity out of a highly regulated
spectrum. The Shannon-Hartley theorem states that
channel capacity increases linearly with increases in
bandwidth and decreases logarithmically with decreases
in the signal to noise ratio (SNR). Although this relation
is only exact under a considerable caution, it does
suggest how capacity is an boost for UWB
communication. Many companies argued that they
should be allowed to intentionally transmit at the
incidental radiated power limits (where they could
already transmit accidentally) over an ultra-wide

bandwidth to take advantage of this capacity potential.
For the FCC approval of UWB devices this dispute was
the inspiration. In February of 2002, the FCC amended
their Part 15 rules (concerning unlicensed radio devices)
to include the operation of UWB devices without a
license. UWB signals as having a fractional bandwidth of
greater than 0.20 or a UWB bandwidth greater than 500
MHz, the FCC states. UWB bandwidth is defined as “the
frequency band bounded by the points that are 10 dB
below the highest radiated emission” The FCC ruling
allows UWB communication devices to function at small
power (an EIRP of -41.3 dBm/MHz) in an unlicensed
spectrum from 3.1 to 10.6 GHz (see Figure1). The low
emission limits for UWB are to ensure that UWB devices
do not cause harmful interference to (i.e. coexist with)
“licensed services and other important radio operations”
(e.g. 802.11a devices).
III ANTENNAS FOR UWB APPLICATION
Directional and Omni- directional are two main groups
of several different types of antennas. This might be used
in narrowband or wideband systems. Directional
antenna is suitable for long distance communications as
they have focused beam with high gain, while Omni-
directional antenna covers a wide area with reasonable
gain. Therefore for small distance and covered
environments, for example office or room Omni-
directional antenna is appropriate. Wireless antennas
may be classified into two separate classes, narrowband
and wideband. The narrowband class demonstrates
tremendous smallness for a given operating bandwidth.
The wideband class possesses extreme bandwidth
capability, capable of covering multiple octaves.
Together classes accomplish performance very near to
the hypothetical Chu-Harrington limit, representing that
they are as small as possible for the showed bandwidth.
The Chu- Harrington graph is a theoretical limit
concerning the volumetric size of an antenna element to
its quality factor or Bandwidth of operation. This
relationship gives the antenna bandwidth of operation.
Bandwidth of operation. This relationship gives the
antenna designer an approximation of a switch between
size and desired bandwidth. There are many issues
involved in designing of UWB systems, such as antenna
design, channel model, and interference. UWB antennas
must cover an extremely wideband of 3.1-10.6 GHz
(lower band 3.1-5.1 GHz, upper band 5.85-10.6 GHz) for
the indoor and handheld applications, have electrically
small size, and high efficiency. In accumulation, they are
required to have a no dispersive characteristic in time
and frequency area, providing narrow pulse duration to
enhance a high data throughput. Antennas in the
frequency domain are typically characterized by
radiation pattern, directivity, impedance matching, and
bandwidth. However, there are certain requirements for
the antennas in the wireless system regardless of ultra-
wideband or narrowband same as regulatory issues,
antenna gain, antenna efficiency, and group delay of
antenna.
IV.ANTENNA GAIN AND EFFICIECY
The required gain is decided by link budget, which is
calculated by taking into account the required channel
quality. As mentioned above a directional antenna will
provide high gain in narrow field with large size
radiator, while an Omni- directional antenna has low
gain in wide field with small size of radiator. When high
gain directional antenna is in use, because the peak
radiated emission limit must meet the regulatory limit
and it should be taken very seriously in mind the
regulatory issues, therefore transfer power should be
reduced, when spending a high gain directional antenna.
In fact regulatory limits are well-defined in terms of
Effective Isotropic Radiated Power (EIRP), system stylish
should try to keep EIRP as much as possible constant
and matching to the regulatory limit. The EIRP is
EIRP= PTx GTx (1)
η = Rrad/(Rrad+Rloss ) (2)
Where PTx transmitting antenna power GTx is
transmitting antenna gain
IV ANTENNA SIZE AND GAIN
Wireless systems needs antennas with small geometrical
dimensions. An antenna is said small when its
geometrical size is small compare to the operating
wavelength and can be fit into a radian sphere of λ/2 .
Particular consideration should be taken in the time of
small antennas design, as small antennas are inefficient
by nature and have high quality factor. The electrical size
of a small Omni-directional antenna may in point of
circumstance be significantly greater than the actual
area of antenna. This follows from the ability of
electromagnetic waves to couple to objects within about
λ/2. Therefore, Even a small physical size antenna can
receive or transmit electromagnetic radiation.
V.ANTENNA SIZE AND BANDWIDTH
The Chu-Harrington limit has investigated basic limits on
antenna size, efficiency, and bandwidth and re-examined
by McLean. This limit is related to the quality factor of
small antenna, which is inverse fractional bandwidth of
antenna too. That means, due to high superiority factor
small antenna provides thin bandwidth. Generally the
antenna bandwidth is limited by size relative to the
wavelength. But, a small antenna could be made
wideband by reducing its internal reflections at its
discontinuities. It is impossible to make an antenna
without discontinuities, because of finite size of antenna,
It is likely to make an antenna as wideband as possible

by constructing a gradual transition between the metal
surface of the antenna and free space. Different approach
can be used for doing this, such as antenna profile,
external resistance or reactance.
VII. CIRCULAR PIN FED LINEARLY POLARIZED PATCH
ANTENNA DESIGN AND ANALYSIS
A planar antenna can be designed based on the above
analysis. The proposed design is described in detail, and
simulation results of the antenna are presented. The
simulation results have been obtained from ANSOFT
DESIGNER 2.0. The structure of antenna is illustrated in
Fig.2a&b. The total length of outer limits of the square
loop antenna should be in one wavelength to have a
linearly polarized radioactivity. Designing the antenna
for 3.1 GHz will give the wavelength of = 96.77 0 mm.
The present antenna composed of a single metallic layer
and printed on a side of a FR4 substrate with dielectric
same side with similar metallic layer. A copper of 0.018
mm thickness has been used as a metallic layer. As
shown in Fig.1 projected antenna is 24 x 25 x 1 mm
dimensionally, which is quite appropriate for wireless
system. The rectangular loop has 98 mm length, which is
fairly close to one wavelength of designed antenna. In
this effort we have used narrowing transmission line for
impedance corresponding, and we modified the shape of
conventional loop antenna with introducing an L portion
to its arms, as shown in Fig. 1, to reduce the antennas
internal reflections at its is continuities and make
gradual transition
a)
b)
Fig.2.a) Top view(b) side view of the antenna structure
(Unit: mm)
Among the metal exterior of the antenna and free
planetary. The narrowing transmission lines have shown
good impedance matching over a wide range of
frequency. The geometry of the taper is chosen to
minimize the reflection and optimize impedance
matching and bandwidth. Also, the use of narrowing in
the antenna structure can make more magnitude of
pulse due to more radiation near to the feed point. The
achieved impedance bandwidth is in the order of 2 GHz
(3.1-5.1 GHz) for VSWR 1.6, as illustrated in Fig. 2. The
antenna gain is illustrated in Fig. 3. It has been detected
that the designed antenna attained almost more than 1.4
dBi improvement in the complete frequency. Fig. 3
shows that the designed antenna gain variation is less
then 0.8 dBi in the total frequency band. The most
problematic part is to preserve the stability of the
radiation pattern across the frequency band for UWB
antenna,. The proposed antenna radiation patterns at
3.1, 4.1, and 5.1 GHz for = 0 and = 90 are illustrated in
Fig. 4. It may be possible to be understood that antenna
almost attained radiation pattern stability across the
frequency band.
Fig.3. Reflection coefficient of proposed antenna
Fig.4 input Impedance Vs frequency Response
Fig.5.VSWR of proposed antenna

Fig.6 Gain (Total –Normalised)
VIII. CONCLUSION
The important thing of this study was to know the
significant aspects of UWB antenna design and how they
are associated to the system performance. UWB
antennas should be designed with specification of flat
amplitude and linear face response over the desired
bandwidth. For UWB system antenna is the significant
part of the system. Its characteristics have an effect on
the overall system performance. An UWB CIRCULAR PIN
FED LINEARLY POLARIZED PATCH ANTENNA was
presented in this work. By introducing an L pattern to
the printed rectangular loop antenna an impedance
bandwidth of 2 GHz can be achieved. The projected
antenna has outstanding performance for smaller band
of the UWB structure and has the attractive features of
small size, low-cost, and easy to design
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Design and Development of Linearly Polarized Patch Antenna of Circular Shape for Lower UWB Band

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Design and Development of Linearly Polarized Patch Antenna of Circular Shape for Lower UWB Band