Microfluidically Loaded Highly Reconfigurable Compact Antennas & RF Devices Gokhan Mumcu Associate Professor Center for Wireless and Microwave Information Systems (WAMI) Department of Electrical Engineering University of South Florida 4202 E. Fowler Ave., Tampa, FL, 33620 IEEE MTT/AP Orlando Chapter Meeting November 30 th , 2016 Forum for Electromagnetic Research Methods and Application Techniques (FERMAT)
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Microfluidically Loaded Highly Reconfigurable
Compact Antennas & RF Devices
Gokhan Mumcu
Associate ProfessorCenter for Wireless and Microwave Information Systems (WAMI)
Department of Electrical EngineeringUniversity of South Florida
The author of this work owns the copyright and no reproduction
in any form is permitted without written permission by the
author.
Abstract
3
Reconfigurable radio frequency (RF) antennas and filters have drawn growing interest to enable compact and light-weight multifunctional systems for wireless communications, sensor networks, biomedical imaging, and remote sensing. Existing reconfigurable RF device design approaches that are based on material loadings, semiconductor and ferroelectric varactors, micromechanical systems (MEMS) switches and capacitors are today well-recognized to offer compact and cost-effective device implementations with high reconfiguration speeds. However, these technologies continue to exhibit limited performance in terms of key RF metrics such as power handling, frequency tunability bandwidth, pattern scanning range, efficiency, and frequency-agile capability. Consequently, novel alternative techniques that address the overall performance needs of reconfigurable RF devices are highly desirable to advance their capabilities and use into mainstream technologies.
This presentation focuses on novel reconfigurable RF antennas, filters, and imaging systems realized by resorting to innovative microfluidic based reconfiguration techniques. The operational principles of these devices rely on continuously movable microfluidic loads consisting of metal (in liquid or solid form) and dielectric solution volumes. The realization of the devices are carried out by utilizing microfluidics and microfabrication techniques with multilayered ultra-thin substrates to maximize the parasitic loading effect of the microfluidic loads for achieving high reconfiguration performances. It will be shown that the proposed microfluidic reconfiguration techniques offer significantly improved frequency tuning range (>4:1 and >2:1 in monopole antenna and filter topologies, respectively) without suffering from excessive loss factors and high power handling issues observed in conventional semiconductor based implementations. Another example design will demonstrate that the microfluidic reconfiguration techniques lead to low-cost mm-wave (30GHz) beam-scanning high-gain antenna arrays without necessitating the use of costly and lossy phase shifters.
A very good impedance matching is achieved – suitable for larger arrays without bandwidth
compromise.
Insertion loss is <2 dB for the complete band (superior to other techniques).
The bandwidth depends on the antenna choice.
5%
6%
7%
8%
9%
1 2 3 4 5 6 7 8
BW
[%
]
Position
Feed Network
Loss
Fabricated Prototype and Characterization (Underway)(publication pending)
42
Array impedance is matched for different switch
positions (i.e. antenna excitations)
Larger S11 ripples in measurements are likely
due to connector – de-embedding is in progress.
Gain measurements are currently in progress.
Integrated Actuation with Piezoelectric Disks(publication pending)
43 MM-Wave devices (phase shifters, filters, and FPAs) require a small amount of metalized plate
displacement.
This motivates for integrating/packaging an actuation mechanism with the device.
Currently, we are investigating achieving actuation with piezoelectric disks – Initial experiment
is done for controlling resonance frequency of an X-band open loop resonator:
1) Piezo electric actuation on a microfluidic channel
Piezo disk actuator
BCB Bonding
Layer
APTES-Treated
LCP Membrane
Silver Epoxy
Microfluidic
Channel
PDMS Chip
Rogers RO6010Moving
Plate
Deflection
Voltage
AppliedDeflection
Increase
Voltage
Increased
Initial PositionPlate MovesFinal Position
2) Experimental Setup
On-Going Work on Other Possible Microfluidically Reconfigurable RF Devices –Textile Antennas (OSU Collaboration)
44
0.0254 mm
LCP
0.012 mm
BCB
2 mm
PDMS
0.51 mm
RT5880
LG
WG
LA
0.9 GHz 0.96 GHz 1.12 GHz 1.28 GHz 1.40 GHz
S1 S2 S3 S4possible locations of
the shorting plate
within the channel
Frequency (GHz)
|S11| (d
B)
S1
S2
S3
S4
Micropumps
Embroidered conductive fibers on
polymer substrates have been found
promising for novel flexible and
conformal electronics.
Goal: Introduce microfluidic based
reconfiguration into the textile
antennas
Technique: The method of using
metalized plates within the
microfluidic channel will be examined
to create microfluidically controlled
varactors and/or switches.
Frequency tunability of 0.9GHz to
1.4GHz is demonstrated with LCP
based antenna prototypes
Integration with textile antenna is
completed by developing the
fabrication procedures – similar
frequency tuning performance is
obtained.
Concluding Remarks
45
Microfluidic Loading of RF devices with:
• Continuously movable metals (in liquid or solid form)
• Dielectric solutions
• Fluidic channels utilizing ultra-thin walls
offers new possibilities & degrees of freedom for RF design:• Miniaturization• Large frequency tuning range• High power handling• Low cost beam-steering• Low loss
Realized wideband frequency tunable monopole antennas with
high radiation efficiencies and high RF power handling
capabilities.
Introduced a new microfluidically controlled metalized plate
technique to alleviate reliability and low conductivity issues of
liquid metals.
Realized frequency-agile bandpass filters with 2:1 frequency
tuning range and high power handling capability.
Introduced a novel technique for low cost and efficient
realization of high gain mm-wave beam-scanning arrays.
Metallized
Areas
Liquid In
Liquid Out
RF In
RF Out
ZCl
ZPl
RP
w
RC
w
Microchannel
Zin
Roger 5880
plate
Journal Publications Related to the Presented Work
46
1. G. Mumcu, A. Dey, and T. Palomo, “Frequency-Agile Bandpass Filters Using Liquid Metal Tunable Broadside Coupled Split Ring
Resonators,” IEEE Microwave and Wireless Components Letters, vol. 23, no. 4, pp. 187 – 189, April 2013.
2. A. Gheethan, M. C. Jo, R. Guldiken, and G. Mumcu, “Microfluidic Based Ka-Band Beam Scanning Focal Plane Array,” IEEE
Antennas and Wireless Propagation Letters, vol. 12, pp. 1638 – 1641, 2013.
3. A. A. Gheethan, A. Dey, and G. Mumcu, “Passive Feed Network Designs for Microfluidic Beam-Scanning Focal Plane Arrays and
Their Performance Evaluation,” IEEE Transactions on Antennas and Propagation, vol. 63, no. 8, pp. 3452 – 3464, Aug. 2015.
4. A. Dey and G. Mumcu, “Microfluidically Controlled Frequency Tunable Monopole Antenna for High Power RF Applications,” IEEE
Antennas and Wireless Propagation Letters, vol. 15, pp. 226 – 229, 2016.
5. T. Palomo and G. Mumcu, “Microfluidically Reconfigurable Metallized Plate Loaded Frequency-Agile RF Bandpass Filters,” IEEE
Transactions on Microwave Theory and Techniques, vol.64, no.1, pp. 158 – 165, Jan. 2016.
6. A. Dey, R. Guldiken, and G. Mumcu, “Microfluidically Reconfigured Wideband Frequency Tunable Liquid Metal Monopole
Antenna,” IEEE Transactions on Antennas and Propagation, vol. 6, no. 6, pp. 2572 – 2576, June 2016.
Conference Publications & Presentations
47
1. A. Gheethan, R. Guldiken, and G. Mumcu, “Microfluidic Enabled Beam Scanning Focal Plane Arrays,” IEEE Antennas and Propagation
Society Symposium, pp. 1 – 4, Orlando, FL, USA, July 2013.
2. A. Dey, R. Guldiken, and G. Mumcu, “Wideband Frequency Tunable Liquid Metal Monopole Antenna,” IEEE Antennas and Propagation
Society Symposium, pp. 1 – 4, Orlando, FL, USA, July 2013 (student paper competition finalist – selected to be among the top 15 out of 141
competing papers).
3. A. Gheethan and G. Mumcu, “MM-Wave Beam Scanning Focal Plane Arrays Using Microfluidic Reconfiguration Techniques,” presented
in URSI - National Radio Science Meeting, Boulder, CO, USA, Jan. 2014.
4. T. Palomo and G. Mumcu, “Highly reconfigurable Bandpass Filters Using Microfluidically Controlled Metalized Glass Plates,” IEEE
International Microwave Symposium (IMS), pp. 1 – 3, Tampa, FL, USA, June 2014.
5. A. Gheethan and G. Mumcu, “2D Beam Scanning Focal Plane Arrays Using Microfluidic Reconfiguration Techniques,” IEEE Antennas
and Propagation Society Symposium, pp. 1 – 4, Memphis, TN, USA, July 2014 (student paper competition honorable mention – selected to
be among the top ~30 out of 149 competing papers).
6. A. Dey and G. Mumcu, “High Resolution Surface Imaging Arrays Interrogated with Microfluidically Controlled Metalized Plates,” IEEE
Antennas and Propagation Society Symposium, pp. 1 – 4, Memphis, TN, USA, July 2014.
7. A. Dey, A. Kiourti, G. Mumcu, and J. L. Volakis, “Microfluidically Reconfigured Frequency Tunable Dipole Antenna,” 9th European
Conference on Antennas and Propagation (EuCAP 2015), pp. 1 – 3, Lisbon, Portugal, Apr. 12–17, 2015.
8. A. Dey and G. Mumcu, “Microfluidically Controlled Metalized Plate Based Frequency Reconfigurable Monopole for High Power RF
applications,” IEEE Antennas and Propagation Society Symposium, pp. 1 – 4, Vancouver, BC, Canada, July 2015.
9. G. Mumcu, “Microfluidic Based High Gain Beam-Scanning Antenna Arrays for MM-Waves and Beyond,” presented in URSI - National
Radio Science Meeting, Boulder, CO, USA, Jan 2016 (invited).
10. A. Dey and G. Mumcu, “Small Microfluidically Tunable Top Loaded Monopole,” IEEE International Workshop on Antenna Technology
(IWAT), pp. 1 – 2, Cocoa Beach, FL, March 2016.
11. E. Gonzalez and G. Mumcu, “A Microfluidically Switched Feed Network for Beam-Scanning Focal Plane Arrays,” IEEE International
Workshop on Antenna Technology (IWAT), pp. 1 – 2, Cocoa Beach, FL, March 2016.