1. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp. 72-79 © IAEME
72
A NOVEL COMPACT SINGLE FED POLARIZATION RECONFIGURABLE
ANTENNA FOR WIRELESS LAN SYSTEMS
Neethu P S1
, Sudha T2
1
(Student, Department of Electronics and Communication, NSS College of Engineering, Palakkad)
2
(Professor, Department of Electronics and Communication, NSS College of Engineering, Palakkad)
ABSTRACT
A single-feed square microstrip patch antenna with polarization reconfigurability is presented
in this paper. Antenna is designed for the WLAN frequency, 2.4GHz (2.4-2.484GHz). A diagonal
slot is inserted in the square patch and a PIN diode is placed on the slot. By switching PIN diode on
the slot, polarization reconfigurability is achieved. When the diode is in the “off-state” antenna
radiates with circular polarization, and in the “on-state” antenna radiates with linear polarization. The
square patch antenna was excited by microstrip line feed and quarter wave transformer is used for
impedance matching.
Keywords: CP, LP, Microstrip Antenna, PIN Diode, Reconfgurable.
1. INTRODUCTION
Microstrip antennas are widely used due to their low profile, light weight, and easy
fabrication [1]. Reconfigurable antennas provide multiple functionality within a limited volume
space. Reconfigurable antenna with polarization diversity can realize frequency reuse, which
expands the capability of communication systems, and are useful when the operating frequency band
is limited. Polarization diversity antennas can also alleviate the harmful influence caused by
multipath effects [2].
Microstrip antennas in their basic form normally provide linear polarization; circular
polarization (CP) operation may be obtained by certain modifications to the basic antenna geometry
and/or feed. Circular polarization (CP) is more attractive in the applications of wireless
communications since the antennas of the transmitter and receiver do not need to be aligned [3].
Circular polarization can be obtained if two orthogonal modes are excited with a 900
time-phase
difference between them [4]. Reconfigurable antenna in [5] uses dual feed to produce circular
polarization. Compared to dual-fed structure single-fed structure is simple and smaller in size. A
single feed structure in [7] switches between two circular and linear polarization, at expense of five
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2. International Journal of Electronics and Communication Engineering &
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp.
switches and three matching stubs. Simple antenna structure with lower size and cost are preferred
for wireless applications.
In this paper, a microstrip patch antenna with switchable polarization using single diode is
presented. A diagonal slot in the square patch produces circular polarization, and inserting diode in
the slot produces a short circuit across the slot resulting in LP. Hence the diode can be biased on and
off to switch polarization and makes the antenna suitable for
reconfigurable antenna was designed and simulated using HFSS v15 on FR4 epoxy substrate of
dielectric constant 4.4 and height of substrat
and its design parameters are discussed. Simulated results, such as radiation pattern, gain plot, return
loss curve etc. are discussed in section 3
2. ANTENNA DESIGN
Structure of square patch antenna is shown in figure 1. Antenna structure consists of square
patch of dimension 28.541mm on a substrate. The substrate is made of 1.6mm thick FR4 epoxy resin
of relative permittivity 4.4. The ground plane covers the rectangular shaped substrate with a side of
66.7x 80mm. Ground plane is a full ground plane with dimensions same as bottom face of
A rectangular slot is cut out diagonally from centre of square patch. Slot dimensions are taken
according to the equation 2.1, where `W
Slot length
PIN diodes are used as switches to achieve polarization reconfigurability. A PIN diode is placed
on the slot. The diode in the ``on-state,'' was simulated by using metal tape (
model used is MA4P2741141T [6], slot is assigned properties of this model.
Fig1: Configuration of square patch antenna
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
6472(Online), Volume 5, Issue 4, April (2014), pp. 72-79 © IAEME
73
switches and three matching stubs. Simple antenna structure with lower size and cost are preferred
In this paper, a microstrip patch antenna with switchable polarization using single diode is
diagonal slot in the square patch produces circular polarization, and inserting diode in
the slot produces a short circuit across the slot resulting in LP. Hence the diode can be biased on and
off to switch polarization and makes the antenna suitable for wireless applications. The
reconfigurable antenna was designed and simulated using HFSS v15 on FR4 epoxy substrate of
dielectric constant 4.4 and height of substrate equal to 1.6 mm. In section 2, structure of the antenna
ussed. Simulated results, such as radiation pattern, gain plot, return
ion 3.
Structure of square patch antenna is shown in figure 1. Antenna structure consists of square
a substrate. The substrate is made of 1.6mm thick FR4 epoxy resin
of relative permittivity 4.4. The ground plane covers the rectangular shaped substrate with a side of
66.7x 80mm. Ground plane is a full ground plane with dimensions same as bottom face of
A rectangular slot is cut out diagonally from centre of square patch. Slot dimensions are taken
according to the equation 2.1, where `W' is the length of square patch.
length =W=2:72 (1)
Slot width =W=27:2
PIN diodes are used as switches to achieve polarization reconfigurability. A PIN diode is placed
state,'' was simulated by using metal tape (10×1mm
slot is assigned properties of this model.
Configuration of square patch antenna
Technology (IJECET), ISSN 0976 –
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switches and three matching stubs. Simple antenna structure with lower size and cost are preferred
In this paper, a microstrip patch antenna with switchable polarization using single diode is
diagonal slot in the square patch produces circular polarization, and inserting diode in
the slot produces a short circuit across the slot resulting in LP. Hence the diode can be biased on and
wireless applications. The
reconfigurable antenna was designed and simulated using HFSS v15 on FR4 epoxy substrate of
, structure of the antenna
ussed. Simulated results, such as radiation pattern, gain plot, return
Structure of square patch antenna is shown in figure 1. Antenna structure consists of square
a substrate. The substrate is made of 1.6mm thick FR4 epoxy resin
of relative permittivity 4.4. The ground plane covers the rectangular shaped substrate with a side of
66.7x 80mm. Ground plane is a full ground plane with dimensions same as bottom face of substrate.
A rectangular slot is cut out diagonally from centre of square patch. Slot dimensions are taken
PIN diodes are used as switches to achieve polarization reconfigurability. A PIN diode is placed
10×1mm2
). PIN diode

3. International Journal of Electronics and Communication Engineering &
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp.
In this simulation, uses 3 for the ON state and perfect open circuit for the OFF state of the
PIN diode. Antenna is fed by microstrip line and a quarter wave transformer at 2.4GHz. Actual input
impedance 243 of antenna is matched to 50
quarter wave transformer. Details of the design paramete
Details of the design parameters
PATCH
SLOT
QUARTERWAVE TRANSFORMER
MICROSTRIP FEED LINE
Basically, in this paper, the square microstrip patch with quarter wave transformer fed is
simulated using computer simulation, HFSSv15 which is a full wave analysis tool based on the finite
element method (FEM). Antenna operating frequency is 2.4GHz, at t
lowest return loss. When the diode is in the ON state the applied field can pass through the switch
and can follow a straight path hence the polarization is linear. Diode in the OFF state introduces
variation in the regular geometry of the antenna
straight and the path of the field is changed such that the resulting polarization is RHCP. The antenna
structure that switches between LHCP and LP can be designed, if the orientatio
changed as shown in Figure 2.
Fig2: Circular polarization for square patch with slots on patch
Fig3: Different senses of the proposed antenna
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
6472(Online), Volume 5, Issue 4, April (2014), pp. 72-79 © IAEME
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for the ON state and perfect open circuit for the OFF state of the
PIN diode. Antenna is fed by microstrip line and a quarter wave transformer at 2.4GHz. Actual input
of antenna is matched to 50 microstrip feed line at resonant frequency b
quarter wave transformer. Details of the design parameters are summarized in table.
Details of the design parameters
LENGTH(mm) BREADTH(mm)
28.541 28.541
10 1
QUARTERWAVE TRANSFORMER 19.971 0.723
MICROSTRIP FEED LINE 28.541 3.059
Basically, in this paper, the square microstrip patch with quarter wave transformer fed is
simulated using computer simulation, HFSSv15 which is a full wave analysis tool based on the finite
element method (FEM). Antenna operating frequency is 2.4GHz, at this frequency antenna shows
lowest return loss. When the diode is in the ON state the applied field can pass through the switch
and can follow a straight path hence the polarization is linear. Diode in the OFF state introduces
etry of the antenna, there is no such path available for the fields to go
straight and the path of the field is changed such that the resulting polarization is RHCP. The antenna
structure that switches between LHCP and LP can be designed, if the orientatio
Circular polarization for square patch with slots on patch
Different senses of the proposed antenna
Technology (IJECET), ISSN 0976 –
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for the ON state and perfect open circuit for the OFF state of the
PIN diode. Antenna is fed by microstrip line and a quarter wave transformer at 2.4GHz. Actual input
microstrip feed line at resonant frequency by using
BREADTH(mm)
Basically, in this paper, the square microstrip patch with quarter wave transformer fed is
simulated using computer simulation, HFSSv15 which is a full wave analysis tool based on the finite
his frequency antenna shows
lowest return loss. When the diode is in the ON state the applied field can pass through the switch
and can follow a straight path hence the polarization is linear. Diode in the OFF state introduces
there is no such path available for the fields to go
straight and the path of the field is changed such that the resulting polarization is RHCP. The antenna
structure that switches between LHCP and LP can be designed, if the orientation of the slot is

4. International Journal of Electronics and Communication Engineering &
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp.
3. RESULTS AND INFERENCES
The switching conditions considered to achieve desired polarization reconfigurabilty are
given in Table 2. Case1 is taken as antenna without diode, which resonates at 2.412GHz with return
loss of -21dB. In case1 antenna shows a band width of 48MHz which is
antenna with diode in the ON state shows 54MHz BW which is 0.2% greater than the previous one
and both are suitable for wireless LAN applications. Circularly polarized antenna shows an axial
ratio of 1.04 at 2.41GHz, and the ax
resonates at 2.44GHz , shift of frequency occurs due to insertion of the diode.
exhibit good impedance matching at resonant frequency. Also produces a good broadside radiation
pattern with RHCP and LP characteristics. 2D radiation pattern is shown in Fig
gain patterns in the X-Z (E) plane and Y
band of operation. E and H plane patterns are almost similar
patterns for antenna with LHCP are also plotted in Fig: 12. Antenna with LHCP shows similar
results as that of RHCP.
Antenna performance parameters for each switching condition of polarization
DIODE POLARIZATION
CASE1 OFF RHCP
CASE2 ON LP
Fig 4: Simulated return loss of antenna for case
Fig 5: Simulated return loss of antenna for case2
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
6472(Online), Volume 5, Issue 4, April (2014), pp. 72-79 © IAEME
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FERENCES
The switching conditions considered to achieve desired polarization reconfigurabilty are
given in Table 2. Case1 is taken as antenna without diode, which resonates at 2.412GHz with return
21dB. In case1 antenna shows a band width of 48MHz which is 2% of the centre frequency,
antenna with diode in the ON state shows 54MHz BW which is 0.2% greater than the previous one
and both are suitable for wireless LAN applications. Circularly polarized antenna shows an axial
ratio of 1.04 at 2.41GHz, and the axial ratio BW (<3dB) is 18 MHZ. Antenna in second case
resonates at 2.44GHz , shift of frequency occurs due to insertion of the diode. Antenna in both cases
exhibit good impedance matching at resonant frequency. Also produces a good broadside radiation
rn with RHCP and LP characteristics. 2D radiation pattern is shown in Fig: 11
plane and Y-Z (H) plane are plotted for lowest axial ratio in frequency
band of operation. E and H plane patterns are almost similar for both cases. The simulated gain
patterns for antenna with LHCP are also plotted in Fig: 12. Antenna with LHCP shows similar
Antenna performance parameters for each switching condition of polarization
POLARIZATION BW[MHz] BW[PERCENTAGE]
RHCP 48 2
LP 54 2.2
Simulated return loss of antenna for case
Simulated return loss of antenna for case2
Technology (IJECET), ISSN 0976 –
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The switching conditions considered to achieve desired polarization reconfigurabilty are
given in Table 2. Case1 is taken as antenna without diode, which resonates at 2.412GHz with return
2% of the centre frequency,
antenna with diode in the ON state shows 54MHz BW which is 0.2% greater than the previous one
and both are suitable for wireless LAN applications. Circularly polarized antenna shows an axial
is 18 MHZ. Antenna in second case
Antenna in both cases
exhibit good impedance matching at resonant frequency. Also produces a good broadside radiation
: 11. The simulated
plane are plotted for lowest axial ratio in frequency
or both cases. The simulated gain
patterns for antenna with LHCP are also plotted in Fig: 12. Antenna with LHCP shows similar
Antenna performance parameters for each switching condition of polarization
GAIN[dB]
1.7
1.6

5. International Journal of Electronics and Communication Engineering &
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp.
Fig 6: Radiation
Fig 7: Radiation
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
6472(Online), Volume 5, Issue 4, April (2014), pp. 72-79 © IAEME
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Radiation pattern of antenna for case 1
Radiation pattern of antenna for case 2
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6. International Journal of Electronics and Communication Engineering &
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp.
Fig 8:
Fig 9:
Fig 10:
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
6472(Online), Volume 5, Issue 4, April (2014), pp. 72-79 © IAEME
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Fig 8: Gain of antenna for case1
Fig 9: Gain of antenna for case 2
Fig 10: Axial ratio of antenna with RHCP
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7. International Journal of Electronics and Communication Engineering &
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp.
Fig 11: Radiation pattern of antenna with LHCP
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
6472(Online), Volume 5, Issue 4, April (2014), pp. 72-79 © IAEME
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Radiation pattern of antenna with LHCP
Fig 12: 2D radiation patte
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8. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
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4. CONCLUSION
Microstrip patch antenna with switchable polarization is presented. Polarization can be
switched between RHCP, LHCP and LP, by controlling the state of one PIN diode. Basic idea of the
proposed design is, slot on the patch, and redirect the surface current, producing circular polarization.
Inserting diode in slot short circuits the slot and produce LP. Electronic reconfiguration is achieved
using PIN diode. Antenna shows good impedance matching for both polarization senses and
broadside radiation pattern with moderate gain. Proposed antenna is a simple and compact design
with single feed suitable for wireless LAN applications. Antenna with reconfigurability in three
senses of polarization is left for future study.
REFERENCES
[1] Youngje Sung, Investigation into the Polarization of Asymmetrical- Feed Triangular
Microstrip Antennas and its Application to Reconfigurable Antennas IEEE Transactions on
Antennas and Propagation, Vol. 58, NO. 4, April 2010.
[2] Xue-Xia Yang, Bing-Cheng Shao, Fan Yang, Atef Z. Elsherbeni and Bo Gong, A Polarization
Reconfigurable Patch Antenna With Loop Slots on the Ground Plane, IEEE Antennas and
Wireless Propagation Letters,Vol. 11,2012.
[3] Shih-Hsun Hsu, Kai Chang [2007]: A Novel Reconfigurable Microstrip Antenna with
Switchable Circular Polarization [J]’, IEEE Antennas and Wireless Propagation Letters, Vol.
6, 2007: 160162.
[4] Balanis, C.A, Antenna Theory: Analysis and Design (Hoboken, New Jersey, John Wiley and
Sons, 1997).
[5] Xue-Xia Yang1, Bo Gong1, Fang Yang Atef Z. Elsherbeni, A reconfigurable patch antenna
with quadri-polarization states using dual feed ports, Antennas and Propagation Society
International Symposium(APSURI),2012 IEEE.
[6] Data Sheet MA4P274-1141T PIN Diodes, MA-com, Application Note.
[7] G Boyon Kim, Bo pan, Symeon Nikolaou, Young-Sik Kim, John Papapolymerou, and Manos
M. Tentzeris, A Novel Single-Feed Circular Microstrip Antenna With Reconfigurable
Polarization Capability, IEEE Trans.on Antennas and Propagation, VOL. 56, 2008.
[8] Uma Shankar Modani and Anubhav Kanwaria, “Triangular Slot Circular Patch Antenna for
Circular Polarization Reconfigurability”, International Journal of Electronics and
Communication Engineering & Technology (IJECET), Volume 4, Issue 4, 2013,
pp. 188 - 197, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472.
[9] Ros Marie C Cleetus and T.Sudha, “Design and Analysis of a Frequency and Pattern
Reconfigurable Microstrip Patch Antenna using Various Electronic Switching Components”,
International Journal of Electronics and Communication Engineering & Technology
(IJECET), Volume 4, Issue 4, 2013, pp. 262 - 271, ISSN Print: 0976- 6464, ISSN Online:
0976 –6472.
[10] Uma Shankar Modani and Anubhav Kanwaria, “Triangular Slot Circular Patch Antenna for
Polarization Reconfigurability”, International Journal of Electronics and Communication
Engineering & Technology (IJECET), Volume 4, Issue 4, 2013, pp. 166 - 175, ISSN Print:
0976- 6464, ISSN Online: 0976 –6472.