Final term presentation made for advanced antenna theory course

1. Riaz Ahmed Liyakath
Department of Electrical Engineering
University of South Florida
Tampa, FL-33620
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2. PRESENTATION OVER-VIEW:
 Introduction to flexible electronics
 Why we go for flexible antennas?
 Materials used for making flexible antennas
 Examples to explain the working of various types of
flexible antennas
 My current research
 Challenges and future scope
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3. REASONS TO MAKE ANTENNAS FLEXIBLE:
Flexible antennas are robust light weight antennas which
are withstand mechanical strain upto a certain extent.
Flexible antennas
Polymer based Carbon nano-
antennas tube antennas
Fig 1. Scope of flexible electronics
Textile antennas Micro fluidic
antennas
Fig 2. Antennas for air-crafts
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4. MATERIALS USED FOR FLEXIBLE ANTENNAS:
1. Polymer based antennas: FABRICTION PROCESS:
i) Silicone elastomers: Polydimethyl Siloxane (PDMS):
Fig 1. Various silicone elastomers
Reasons to opt for PDMS:
PDMS an inexpensive, flexible
polymer
Can withstand mechanical strain
Can be mixed and cured at room
temperature
Dielectric properties can be tuned.
ii) PDMS- ceramic composites:
Fig 2. Patch antenna made from PDMS- ceramic composite
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5. 3. Compressed Nano tubes:
Fig 1. CNT based antenna
APPLICATIONS:
High gain-beamforming antennas
for wireless systems
4. Micro fluidics/ Liquid metals:
Liquid metals are filled in micro-fluidic
5. Textiles:
cavities in an silicone elastomer.
 FlecTron
The liquid metal prevents loss of
electrical connectivity when the antenna fleece fabric
is deformed.
Conductive
 Liquid metal antennas on the other textiles coated
hand, can conform to any shape without with Carbon
strain and can be reversibly deformed. nanotubes(CNTs)
and gold
Fig 2. Twisted liquid metal antenna
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6. LIQUID METAL PLANAR INVERTED CONE ANTENNA (PICA):
The planar inverted cone
antenna (PICA) operates in
the Ultra wide band (UWB) of
frequency 3.1 to 10.6 GHz
Fig. 2: Feed cable
Fig. 1: Sketch of feed cable Fig. 3: Return loss and efficiency
connection to the antenna
The antenna is manufactured by
injecting liquid metal into micro-
structured channels in the elastic
PDMS material.
The antenna has a good return loss
of 10 dB in the operating frequency
and the radiation efficiency was also
observed to be greater than 70%
which is considered good.
Fig. 3: Photographs of the stretchable PICA: (a) and (c)
The produced antenna allows non-stretched antenna, (b) stretched antenna with 40%
stretching up to 40%. y-axis elongation, (d) stretched antenna with 40% -axis
elongation, (e) folded antenna, and (f) twisted antenna.
It is a highly broadband antenna
Shi Cheng, Zhigang Wu, Paul Hallbjörner, Klas Hjort, Anders Rydberg, “Foldable and Stretchable Liquid Metal Planar Inverted Cone Antenna”, IEEE
Transactions on Antennas and Propogation, Vol. 57, No. 12, Dec 2009 6

7. REVERSIBLY DEFORMABLE AND MECHANICALLY TUNABLE
FLUIDIC ANTENNAS :
The antenna consist of a fluid metal alloy ( eutectic Fabrication Process:
gallium indium - EGaIn) injected into micro fluidic
channels comprising a silicone elastomer (PDMS).
FLUIDIC DIPOLE FEATURES:
 Withstand mechanical deformation (stretching,
bending, rolling, and twisting)
Resonant frequency can be tuned mechanically
by elongating the antenna
Resonates at 1962 MHz
Efficiency is around 90%(approx.) at a broad Fig,.3: Measured reflection coefficient of the dipole both in
frequency range (1910–1990 MHz) its ‘‘relaxed’’ position (54mm length) and mechanically
The size of antenna is 54 mm elongated positions (58, 62, and 66mm length) as a function
of frequency. The ability to stretch the antenna allows the
Simple to fabricate frequency to be tuned mechanically.
Fig 1. prototype antenna being stretched
Figure 4. Resonance frequency of a fluidic dipole
antenna as a function of the length of the antenna
as modulated by stretching
Ju-Hee So, Jacob Thelen, Amit Qusba, Gerard J. Hayes, Gianluca Lazzi,
and Michael D. Dickey, „Reversibly Deformable and Mechanically Tunable Fluidic
Fig 2. prototype antenna being rolled (left) and antenna Antennas‟ , Adv. Funct. Mater. 2009, 19, 3632–3637 7
self-heals in response to sharp cuts

8. ELASTIC ANTENNAS BY METALLISED ELASTOMERS:
Fig 4. Radiation patterns
Fig 3. Ultra-wideband monopole antenna
The objective of this is to investigate Elastic
antennas made by metallised elastomers at RF
frequencies for microwave transmission lines
and antennas applications
Fig 1: Elastic coplanar waveguide:
Fig 5: Simulated return loss of
Fig 2: Normal coplanar waveguide: ultra-wideband antennas
Both give radiation
patterns as expected
for a normal
monopole antenna
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9. Table 1: Conductor thickness vs. Efficiency
Fig.6 : Self-compensating antenna
The below table shows that the conductor thickness is
important for designing an efficient antenna
Fig 7: Simulated return loss after stretching
Qing Liu, Kenneth Lee Ford, Richard Langley,”Elastic
Antennas by Metallised Elastomers”, 2010
Loughborough Antennas & Propagation Conference,
Nov 2010
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10. A MILLIMETER-WAVE MICROSTRIP ANTENNA ARRAY ON ULTRA-FLEXIBLE
MICRO MACHINED POLYDIMETHYLSILOXANE (PDMS) POLYMER:
 As bulk PDMS is demonstrated to be lossy at millimeter
waves, membrane-supported devices are considered. Antenna array
 A new reliable and robust technological process has been Fig. 2. (a) Layout of the
developed to micro machine membrane-supported A 4 X 2-element
transmission lines and microstrip antenna arrays. microstrip antenna array
supported by a PDMS microstrip antenna array
Transmission lines membrane supported by a 20-
and zoom to see rounded micro meter-thick
The insertion loss of microstrip lines
angles. (b) 3-D schematic PDMS membrane is
fabricated on 20- m-thick membranes is of the designed.
about 0.5 dB/cm at 60 GHz. antenna array. (c)
Photograph of the
fabricated prototype
Fig. 3(below). Measured
and computed radiation
patterns of the membrane
supported microstrip
antenna array at 55 GHz.
(a) H-plane. (b) E-plane
Fig. 1. (a) Schematic view of 50- ohm transmission lines printed on bulk
PDMS and PDMS membranes . (b) Bulk PDMS transmission line in the Sami Hage-Ali, Nicolas Tiercelin, Philippe Coquet, Ronan
impedance measurement setup based on an Anritsu Universal test fixture 3680 Fig. 3. (a) Reflection coefficient Sauleau, Hiroyuki Fujita, Vladimir Preobrazhensky, and Philippe
Pernodm,‟ A Millimeter-Wave Microstrip Antenna Array on Ultra-
V. (c) 50-ohm transmission line on a PDMS membrane d) Measured and and (b) input impedance of the
Flexible Micromachined Polydimethylsiloxane (PDMS) Polymer‟
computed insertion loss of 50-ohm transmission lines printed on bulk PDMS antenna array. , IEEE ANTENNAS AND WIRELESS PROPAGATION 10
and 20-m-thick PDMS membranes LETTERS, VOL. 8, 2009

11. DESIGN AND MANUFACTURING OF STRETCHABLE HIGH-FREQUENCY
INTERCONNECTS:
 Meander-shaped
conductors in a coplanar
waveguide topology.
 They are produced based
on laser-ablation of a
copper foil, which is then
embedded in a highly
stretchable bio-compatible Fig. 1 Structure of the entire
silicone material - Silastic external interconnection
MDX4-4210 .
Fig. 2 Comparative simulation of the magnitude of the reflection
coefficient of a straight and horseshoe-shaped CPW
Fig. 5 Tapered interconnection between the pads
and the CPW
Maximal magnitude of -14 dB
Fig 3. Horse-shaped CPW for the reflection coefficient
and a minimal magnitude of -4
dB for the transmission
coefficient in the frequency
band up to 3 GHz.
Neither magnitude nor the
phase of the transmission
coefficient was influenced by
elongations up to 20%.
Fig 4. Structure of the flexible Fig. 6 Close up of the horseshoe-shaped CPW
link
Fig. 5 Close up of the horseshoe-shaped CPW
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Fig. 7 Prototype stretchable high-frequency interconnect

12. ROBUST PLANAR TEXTILE ANTENNA FOR WIRELESS BODY LANS
OPERATING IN 2.45 GHZ ISM BAND:
A single-feed rectangular-ring textile
antenna is proposed for wireless body
area networks operating in the 2.45
GHz ISM band.
Conductive part - FlecTron
Non-conductive antenna substrate -fleece fabric
Fig. 2 Measured and simulated return loss (S11) Fig. 3 Measured antenna gain along broadside
Fig. 4 Simulated antenna gain at
2.45 GHz
a xz-plane
b yz-plane
ADVANATGES:
Highly efficient
Flexible
Wearable
A. Tronquo, H. Rogier, C. Hertleer and L. Van Langenhove, „Robust
planar textile antenna for wireless body LANs operating in 2.45 GHz
Fig. 1 Geometry of rectangular-ring microstrip textile antenna ISM band‟ , ELECTRONICS LETTERS 2nd February 2006 .
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13. DUAL-BAND TEXTILE ANTENNA USING AN EBG STRUCTURE:
Antenna on EBG geometry
The antenna is fully characterized in free space
and on the body model, with and without an
electromagnetic band gap (EBG) substrate.
 The bandgap array consists of 3 3 elements
and is used to reduce the interaction with human
tissues.
 With the EBG back reflector, the radiation into
the body is reduced by more than 15 dB.
Increases of 5.2 dB and 3 dB gain are noticed at
2.45 GHz and 5.5 GHz, respectively.
Dual-band coplanar antenna.
The efficiency of the antenna combined with the EBG
structure and placed 1 mm above the homogeneous phantom,
significantly increases (83% at 2.45 GHz and 86% at 5.5
GHz).
EBG geometry
Nacer Chahat1, Maxim Zhadobov, Ronan Sauleau,
Kouroch Mahdjoubi, „Improvement of the On-Body
Performance of a Dual-Band Textile Antenna Using an
EBG structure ‟, 2010 Loughborough Antennas &
Propagation Conference
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14. A FLEXIBLE MONOPOLE ANTENNA WITH BAND-NOTCH FUNCTION FOR
UWB SYSTEMS:
Fig 1. Rolled type flexible antenna
 A flexible monopole antenna for UWB
systems which can cover the frequency
band 3.1 - 10.6 GHz is proposed and
fabricated on PET film having the
flexible characteristic.
 To obtain the wide bandwidth, the
stepped CPW feed line and the declined
shape of the ground plane is used.
 It has a band-notch function of 5 GHz
WLAN band using two slits. Thisis
used to reject 5 GHz band, which
includes the limited band by
IEEE802. 1 la and HIPERLAN/2.
Fig 2. Rolled type flexible antenna
Fig 3. The parameter study of Su Won Bae, Hyung Kuk Yoon, Woo Suk Kang, Young Joong Yoon and Cheon-Hee Lee,
the length of the slit of the „A Flexible Monopole Antenna with Band-notch Function for UWB Systems‟ , Proceedings of
flexible UWB antenna Asia-Pacific Microwave Conference 2007 14

15. OPTICALLY TRANSPARENT ULTRA-WIDEBAND ANTENNA:
Optically transparent ultra-wideband (UWB) disc monopole
using AgHT-4 transparent film is designed.
The antenna is fed by a 50 V coplanar waveguide
Its operational bandwidth is measured from 1 to 8.5 GHz.
Fig. 1 UWB transparent antenna
Fig. 2 Measured and simulated return loss
Fig. 3 Gain sweep for transparent and aluminum
UWB antenna using coaxial and optical fibre
Fig. 4 H (left) and E-plane radiation patterns for transparent and aluminium UWB
APPLICATIONS:
Vehicles,
Building windows,
Computer video monitors
Solar photovoltaic panels
A. Katsounaros, Y. Hao, N. Collings
and W.A. Crossland, „Optically
transparent ultra-wideband antenna‟,
ELECTRONICS LETTERS 2nd July
2009 Vol. 45 No. 14
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16. MY RESEARCH:
We plan to make a planar antenna on a flexible substrate that can be tuned to work over a range of frequencies by
stretching the substrate.
STRETCH ALONG LENGTH:
5% stretch
S11
0
-5
Mag. [dB]
m1 -10
f req=2.427GHz
dB(new stlen5per_mom_a..S(1,1))=-23.646 -15
Min
-20
m1
-25
25% stretch 1.0 1.5 2.0 2.5 3.0
Frequency
3.5 4.0 4.5 5.0
m1 S11
freq=2.057GHz 0
dB(newstlen25per_mom_a..S(1,1))=-31.789
Fig 1.Fundamental idea Min -10
Mag. [dB]
-20
-30
m1
-40
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Frequency
STRETCH ALONG WIDTH:
10% stretch 0
S11
m1
freq=2.537GHz -10
dB(newstwid5per_mom_a..S(1,1))=-41.608
Min
Mag. [dB]
-20
-30
m1
Fig 2. 4-probe measurement -40
Set-up (left) and fabricated -50
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
PDMS film (right) Frequency
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17. WHAT FUTURE HOLDS FOR THESE ANTENNAS:
E-Textiles
Military
Flexible RFID tags Flexible
antennas
Medicine
Air-planes
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