-
cases is that we added one or two more obstacles into the
simu-
lation. As the number of the obstacles increases, the
perform-
ance of the wideband antenna system response decreases.
Comparing Figures 7 and 9(c), we find that the distortion in
Figure 9(c) is less than that in Figure 7. Although there
are
more obstacles present in the case of Figure 9(c), because
plate
#1 is absent, there is a direct path from the transmit to
the
receiving antenna. The signal directly radiated from the
transmit
antenna is stronger than the scattered ones. Therefore, even
though there are other obstacles present in the environment,
the
received current is very close to that one of Figure 4, which
has
no obstacles at all.
It is interesting to observe that the distortion in Figure 9(a)
is
smaller than the distortion in Figure 4 when no obstacle is
present!
4. CONCLUSION
The combination of the transmitting biconical and the
receiving
TEM-horn antenna pair can transmit and receive time-domain
wideband signals with little distortion. But if there are
obstacles
present in between them, especially when the antennas are
oper-
ating in the near field region, the performance degrades
significantly.
However, if the obstacles are located in the far-field
region,
the distortion is less than in the near field region,
particularly if
a direct line of sight is present. Then with this transmit
receive
pair, one can propagate wideband signals, without much
distor-
tion, especially when there are no obstacles blocking the
direct
transmission path. Particularly, the effect of the obstacles
is
small and the performance is close to the case when there
are
no obstacles present at all.
REFERENCES
1. J.R. Andrews, UWB Signal Sources, Antennas and
Propagation,
Picosecond Pulse Lab, Application Note AN-14a, August,
Boulder,
CO, 2003. (Also presented at the 2003 Honolulu IEEE Wireless
Conference.) Available at:
http://www.picosecond.com/objects/AN-
14a.pdf
2. T.K. Sarkar, M. Salazar-Palma, and E.L. Mokole, Physics of
multi-
antenna systems and broadband processing, John Wiley and
Sons,
Hoboken, NJ, 2008.
3. C. Ryan, Jr., E. Weaver, and B. Cown, Plane wave spectrum
scat-
tering analysis of near-field obstacle effects on directive
antenna
patterns, IEEE Trans Antennas Propag 27 (1979), 772778.
4. J.E. Storer and J. Sevick, General theory of plane-wave
scattering
from finite, conducting obstacles with application to the
two-
antenna problems, J Appl Phys 25 (1954), 369.
5. Z. Mei, T.K. Sarkar, and M. Salazar-Palma, The design of an
ultra-
wideband T-pulse with a linear phase fitting the FCC mask,
IEEE
Trans Antennas Propag 59 (2011), 14321436.
VC 2013 Wiley Periodicals, Inc.
COMPACT RECONFIGURABLE DUALFREQUENCY MICROSTRIP PATCHANTENNA FOR
3G AND 4G MOBILECOMMUNICATION TECHNOLOGIES
Younes Karfa Bekali1 and Mohamed Essaaidi21 Information and
Telecommunication Systems Lab, AbdelmalekEssaadi University,
Tetuan, Morocco2 ENSIAS, Mohamed V Souissi University, Rabat,
Morocco;Corresponding author: [email protected]
Received 25 November 2012
ABSTRACT: We propose in this article, a novel
compactreconfigurable patch antenna with frequency diversity. This
antenna can
be tuned by changing the switching mode of two PIN diodes from
theONON state to OFFOFF state to switch it over two different
mobilecommunication technologies, namely 3G and 4G. The antenna has
a
simple geometry and a small structure, its dimensions are 45 38
1.5 mm3 and it is printed on an FR4 substrate with a thickness of
1.5mm. The prototype of this antenna has been fabricated and
tested. The
measurement results confirmed the simulation predictions in
terms offrequency diversity performances. VC 2013 Wiley
Periodicals, Inc.
Microwave Opt Technol Lett 55:16221626, 2013; View this
article
online at wileyonlinelibrary.com. DOI 10.1002/mop.27649
Key words: patch antenna; frequency reconfigurable;
reconfigurableantenna; switching mode; dual frequency
1. INTRODUCTION
The emergence of reconfigurable antennas has been a great
de-
velopment in the field of telecommunication and wireless
tech-
nologies, as this generation of antennas helped to achieve
good
performances with a small size and low cost. Many of the
wire-
less communication technologies today require antennas that
op-
erate at more than just one frequency while maintaining a
small
size [1]. Reconfigurable antennas play a key role in modern
tele-
communication systems [2].
In this article, we present a new design of a reconfigurable
circu-
lar patch antenna with switchable slot using two PIN diode
switches.
This antenna can operate easily at two frequencies depending on
the
bias state of these two switches. The desired antenna
performances
are obtained through a parametric study which optimized the
fre-
quency response of the antenna in different switch states.
The proposed reconfigurable antenna is desirable for several
mobile and wireless communication technologies and standards
such as 3G and 4G. As far as the reconfigurable behavior is
con-
cerned, there are many techniques that have been proposed
and
implemented successfully to achieve frequency diversity [2].
Most of these techniques are based on different switching
tech-
niques including PIN diodes, GaAs field-effect transistor,
and
RF micro-electronic mechanical system (MEMS) switches [3].
The PIN diode play behaves like a switch that can go from
the
ON state to OFF state depending on its bias state, which is
con-
trolled by DC bias currents fed through vias. When the switch
is
in the ON state, it is modeled as a very thin metal tape
while
the OFF mode it is an open circuit [1]. MEMS switches have
been simulated by transmission lines for the closed state
and
for the open state the switches are simply removed [3]. But
in reality, the electrical behavior of PIN diodes slightly
influen-
ces the development patterns of current in the patch. We can
also use MEMS like a switch for this antenna. The proposed
antenna design and performances are optimized using CST
Microwave Studio [4]. A first validation of the simulation
results, prior to the prototype production and measurement
tests,
TABLE 1
Example Output Current Distortion Variable E
Example 1 Figure 3 0.1427
Example 2 Figure 4 0.1970
Example 3 Figure 6 2.1137
Example 4 Figure 7 0.3285
Example 5(a) Figure 9(a) 0.4200
Example 5(b) Figure 9(b) 0.4261
Example 5(c) Figure 9(c) 0.1815
1622 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 55, No. 7,
July 2013 DOI 10.1002/mop
-
is carried out using another of the shelf commercial EM
simula-
tor, namely, Ansoft High Frequency Structure Simulator
(HFSS)
[5].
2. ANTENNA DESIGN PROCEDURE
2.1. Geometry of the AntennaThe geometry of the proposed
switchable printed circular patch
antenna is shown in Figure 1. It consists of a printed
circular
patch antenna on an FR4 epoxy substrate with a thickness of
1.5
mm and a relative permittivity of er 4.4. The substrate has
alength of 45 mm and a width of 38 mm. The dimensions of the
truncated ground plane are 38 10.6 mm2 and the radius of
cir-cular patch is 8 mm.
The excitation is launched through a 50-X microstrip feedline
having a width of 2.8 mm. In order to achieve frequency di-
versity for this antenna, a slot has been introduced in it and
two
switches are inserted close to the edges of this slot (Fig. 1).
The
switches are being used to change the geometry of the disc
antenna producing a reconfigurable antenna structure that
offers
Figure 1 Geometry of the novel reconfigurable patch antenna (a)
with and (b) without switches
Figure 2 Geometry of the slot
Figure 3 PIN diode DC bias circuit
TABLE 1 Dimensions of the Proposed ReconfigurableAntenna
FR4 Substrate (X, Y, Z) 38 45 1.5 mm3
Disc Radius R 8 mmPosition of Center of the Disc (X, Y, Z)
(19,28,1.5) mm3
Width of Microstrip Feed Line w 2.8 mm
Ground Plane (X, Y) 38 10.5 mm2Feed Line Length h 24 mm
TABLE 2 Dimensions of the Slot
Distance Length (mm)
d1 1.0
d2 2.5d3 12.0
d4 13.0d5 0.5
Figure 4 Simulated return loss for the proposed
reconfigurableantenna for ONON state. [Color figure can be viewed
in the online
issue, which is available at wileyonlinelibrary.com]
DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol.
55, No. 7, July 2013 1623
-
more frequency agility. The dimensions of all parts of this
antenna are presented in Table 1. The geometry and
dimensions
of the slot are presented in Figure 2 and Table 2.
2.2. Switching TechniqueIn order to achieve reconfigurable
antenna behavior with fre-
quency diversity, PIN diodes or RF MEMS can be used [610].
In this proposed reconfigurable antenna design, the PIN
BAR63
model [11] is used due to its weak capacity in blocked mode.
This ensures a good isolation on a relatively broad band.
The
PIN diodes are biased using a DC bias circuit that controls
the
way they operate as shown in Figure 3. In the remaining part
of
this article, we will simulate the diodes behavior according
to
two different ways. The first simulation method of the diode
consists of substituting it by its electrical characteristics.
The
PIN diodes, in ON state and OFF state, are easily modeled by
Figure 6 Prototype of compact dual frequency reconfigurable
microstrip patch antenna: (a) slot (b) antenna photos. [Color
figure can be viewed in theonline issue, which is available at
wileyonlinelibrary.com]
Figure 7 Return loss characteristics of dual frequency
microstrip patch antenna (a) OFFOFF state (b) ONON state. [Color
figure can be viewed inthe online issue, which is available at
wileyonlinelibrary.com]
Figure 8 E- and H-plane radiation patterns for the proposed
reconfig-urable antenna at 2.1 GHz for ONON state. [Color figure
can be
viewed in the online issue, which is available at
wileyonlinelibrary.com]
Figure 5 Simulated return loss for the proposed
reconfigurableantenna for OFFOFF state. [Color figure can be viewed
in the online
issue, which is available at wileyonlinelibrary.com]
1624 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 55, No. 7,
July 2013 DOI 10.1002/mop
-
series RLC circuits. The BAR63 PIN diode considered in this
design can be modeled in the ON state by a resistor of 0.5 X
inseries with an inductor of 0.5 nH. In OFF mode, it is repre-
sented by a capacitor of 0.15 pF [11].
According to a second method, the switch is removed from
the simulation and the patch should be simulated with a com-
plete slot in the OFF mode. When the switch is ON, the PIN
diode is replaced by a very thin metal tape with a width of
0.1
mm in the simulations.
3. RESULTS AND DISCUSSION
Figure 4 shows the return loss for ONON state for both CST
and HFSS simulations. We can see that the antenna operates
at
frequency bands ranging from 2 to 2.26 GHz (HFSS) and 1.8
2.47 GHz (CST). These frequency bands include the frequency
band around 2.1 GHz corresponding to third generation mobile
communications, namely, 3G.
The results obtained for the OFFOFF state are presented in
Figure 5, which shows a good agreement between HFSS and
CST simulations. It is easily seen that HFSS results give a
band-
width from 2.33 to 3.02 GHz while those obtained from CST
simulations give a bandwidth ranging from 2.2 to 3 GHz. So,
both of them cover the frequency band around 2.6 GHz corre-
sponding to 4G mobile communication technologies.
These simulations were used as a basis for the optimization
and validation of the proposed reconfigurable antenna for 3G
and 4G mobile communications. As a consequence of them, a
prototype of this antenna was fabricated (Fig. 6) and
measured.
The measured return loss of this antenna confirms the simu-
lations of two frequency bands related with the ONON mode
[Fig. 7(a)] and the OFFOFF mode [Fig. 7(b)] corresponding,
respectively, to 2.1 and 2.6 GHz frequency bands
standardized
for 3G and 4G mobile communication technologies.
The E- and H-plane radiation patterns of the proposed recon-
figurable antenna for 2.1 and 2.6 GHz are depicted in Figures
8
and 9, respectively. These radiation patterns have a
dipole-like
behavior.
The gain of the antenna is illustrated in Figure 10 for 2.1
GHz corresponding to ONON state and Figure 11 for 2.6 GHz
frequency band related with OFFOFF state. It is found that
the
maximum gain is obtained for the ONON state which is 7.9
dB, while the maximum gain for the OFFOFF state is about
5.88 dB at 2.6 GHz.
4. CONCLUSION
A novel compact single feed microstrip antenna with
reconfigur-
able frequency capability for frequency diversity
applications
has been designed, constructed, and measured in this
article.
Figure 10 Gain (dB) for / 0 and / 90 at 2.1 GHz for ONON state.
[Color figure can be viewed in the online issue, which is available
atwileyonlinelibrary.com]
Figure 9 E- and H-plane radiation patterns for the proposed
reconfig-urable antenna at 2.6 GHz for the OFFOFF state. [Color
figure can be
viewed in the online issue, which is available at
wileyonlinelibrary.com]
DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol.
55, No. 7, July 2013 1625
-
The agreement between simulation and measured results is
very
good. PIN diode switches are used to tune the proposed
recon-
figurable antenna between the two operating frequency bands
corresponding to 3G and 4G mobile communication technolo-
gies. The radiation pattern and the gain of the antenna have
been also investigated and make it, together with its small
size,
a very good candidate for mobile 3G and 4G smart phones and
tablets handsets.
REFERENCES
1. T. Al-Maznaee and H.E. Abd-El-Raouf, Design of
reconfigurable
patch antenna with a switchable V-Slot, Prog Electromagn Res C
6
(2009), 145158.
2. G. Monti, L. Corchia, and L. Tarricone, Patch antenna with
recon-
figurable polarisation, Prog Electromagn Res C 9 (2009),
1323.
3. J.A. DeSignor and J. Venkataraman, Reconfigurable dual
frequency
microstrip patch antenna using RF MEMS switches, Department
of
Electrical Engineering Rochester Institute of Technology,
Roches-
ter, NY (report).
4. Computer Simulation Technology, Available at: http://
www.cst.com.
5. Ansoft High Frequency Structure Simulator Corporation, V
9.2,
2004, Available at: http://www.ansoft.com/hfss.
6. M.T. Ali, M.R. Kamarudin, and T.A. Rahman, Design of
reconfig-
urable multiple elements microstrip rectangular linear array
antenna, Prog Electromagn Res C 6 (2009), 2135.
7. H. Torpi and Y. Damgaci, Design of dual-band
reconfigurable
smart antenna, Progress in Electromagnetics Research
Symposium,
Prague, Czech Republic, 2007, August 2730.
8. S. Nikolaou, R. Bairavasubramanian, C. Lugo, I. Carrasquillo,
D.C.
Thompson, George, E. Ponchak, J. Papapolymerou, and M.M.
Tentzeris, Pattern and frequency reconfigurable annular slot
antenna using PIN diodes, IEEE Trans Antennas Propag 54
(2006).
9. R. Saranya and K. Ramprakash, Design of reconfigurable
antenna
array for WLAN and WIMAX application, In: Proceedings of the
international conference on manmachine systems (ICoMMS), 11
13 October 2009, Batu Ferringhi, Penang, Malaysia.
10. H. Kim, D. Chung, D.E. Anagnostou, Y.J. Yoon, and J.
Papapoly-
mero, Hardwired Design of Ultra-Wideband Reconfigurable
MEMS Antenna, In: 18th annual IEEE international symposium
on
personal, indoor and mobile radio communications (PIMRC007).
11. Infineon, Silicon PIN BAR63 Diode, Datasheet. Available
at:
http://www.infineon.com.
VC 2013 Wiley Periodicals, Inc.
CARD-TYPE SLOT ANTENNA FOR UHFRFID TAG CLOSE TO THE CHEST OF
AHUMAN BODY
Chien-Wen Chiu, Chen-An Ou, Hwang-Cheng Wang,and Yu-Chou
ChuangDepartment of Electronic Engineering, National Ilan
University, Ilan260, Taiwan; Corresponding author:
[email protected]
Received 22 October 2012
ABSTRACT: This article presents a UHF radio frequency
identificationtag antenna used in proximity to the chest of a human
body for student
ID card identification. The proposed tag antenna is a
rectangular slot-type patch structure printed on a PVC card. For
near-body applications,
stratified square plates with physical parameters are used as a
humanmodel. The radiation properties of the slotted tag antenna
placed nearthe model and the absorption effects due to human body
are
investigated. The research used the HFSS simulator to optimally
designthe antenna and employed the FEKO simulator to verify the
simulated
results. The designed tag was constructed for testing the
reading range.The measured reading range achieved is around 4.2 m
as the tag is putclose to the chest. VC 2013 Wiley Periodicals,
Inc. Microwave Opt
Technol Lett 55:16261631, 2013; View this article online at
wileyonlinelibrary.com. DOI 10.1002/mop.27610
Key words: UHF radio frequency identification tag; slot antenna;
tag
antenna; human body effect; read range
1. INTRODUCTION
Radio frequency identification (RFID) is a rapidly
developing
technology which uses RF signals for the automatic
identifica-
tion of objects. Nowadays, RFID finds many applications in
Figure 11 Gain (dB) at / 0 and / 90 at 2.6 GHz for OFFOFF state.
[Color figure can be viewed in the online issue, which is available
atwileyonlinelibrary.com]
1626 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 55, No. 7,
July 2013 DOI 10.1002/mop
-
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