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Hadi Mirzajani

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Hadi Mirzajani Powered By Docstoc
					              SAHAND University of Technology
              Electrical Engineering Department
                Microelectronic research Lab




    Design and Simulation of a
MEMS-based Frequency Reconfigurable
    Microstrip Patch Antenna

         Researcher: Hadi Mirzajani

       Supervisor : Dr. Habib Badri Ghavifekr



                     September of 2012
                         Agenda

1. Introduction and Motivation

2. Literature Review

3. MEMS Frequency Tunable Microstrip Patch Antenna Design

4. Conclusion

5. Future Works

6. Publications


 1
1. Introduction




        Multi-frequency applications

        Elimination of fabrication process tolerances on
         antenna operating frequency

        Reduction of intermodulation distortion

        Elimination of cross talk effect




 2
2. Literature Review
MEMS have been incorporated in frequency tunable antennas in
                    a number of ways:


      Reactive Loading the antenna by MEMS reactive devices

      Changing the dimensions of effective radiating element by MEMS
      switches

      Changing the antenna substrate material dimensions in order to
      change effective dielectric constant




 3
2. Literature Review
2.1 Reactive Loading the antenna by MEMS reactive devices
 According to transmission line model approximation:


                                             L= Length of the rectangular patch
                                             W= Width of the rectangular patch
                                             xo= Feed point location along length of the patch
                                             h= Thickness of the substrate material
                                             c= Velocity of light
                                             f= Design frequency
                                             εr= Relative permittivity of the substrate material

      Rectangular Microstrip patch antenna             Circuit model of Rectangular Microstrip patch
                                                                          antenna




  4
2. Literature Review
2.1 Reactive Loading the antenna by MEMS reactive devices




                                                                                 Microstrip Antenna


                                                                                Microstrip Transmission Line
                                                                                Tapered Line

                                                        CPW Section
      The antenna resonant frequency can continuously be shifted from 16.05 GHz down to
               15.75 GHz as the actuation voltage is increased from 0 to 11.9 V.

 Erdil E, Topalli K, Unlu M, Civi O A, Akin T (2007) Frequency Tunable Microstrip Patch Antenna Using RF MEMS Technology. IEEE transactions on
  antennas and propagation 55(4):1193-1196

  5
2. Literature Review
2.2 Changing the dimensions of effective radiating element by MEMS switches

 MEMS switches
     is used to
   interconnect                                                  Patch
   pixels. (based on
      design and application).




  Reconfiguration in;
   Frequency
   Directivity
   Polarization
  Besoli A G, De Flaviis F (2011) A Multifunctional
   Reconfigurable Pixeled Antenna Using MEMS
   Technology on Printed Circuit Board. IEEE
   Transactions on Antennas and Propagation
   59(12):4413-4424

  6
 2. Literature Review
 2.2 Changing the dimensions of effective radiating element by MEMS switches




                                                                           Closed-up view of MEMS switches

4 MEMS switches are divided the antenna into 5 segments
                                                                  Resonant frequency shift of the antenna, 19.4 – 20.9 GHz


                                             MEMS up/down combinations considered to modify the resonant frequency of the antenna

                                                                 a              b              c             d               e
    Paolo Arcioni, L. P. a. G. C. (2007).
     A Novel Low Reflection-Loss                  M1           DOWN            UP           DOWN           DOWN              UP
     MEMS      Reconfigurable       Patch         M2           DOWN            UP             UP           DOWN              UP
     Antenna. 10th European Conference            M3           DOWN          DOWN             UP             UP              UP
     on Wireless Technology. Munich
                                                  M4           DOWN          DOWN           DOWN             UP              UP
     Germany.

    7
2. Literature Review
2.3 Changing the antenna substrate material dimensions
 According to transmission line model approximation:

                                                                                                         r ( h2  h1 )
                                                                                               eff 
                                                                                                         h2   r h1

                                                                           εr = dielectric constant of the Kapton film
                                                                           h2 = thickness of the Kapton dielectric layer
                                                                           h1 = is the air gap height



 Continuous frequency tuning from
  16.91 to 16.61GHz by an actuation
  voltage of 165 V


  Jackson Jr R, Ramadoss R (2007) A MEMS-based electrostatically tunable circular microstrip patch
   antenna. J. Micromech. Microeng. 17:1-8

  8
2. Literature Review
2.3 Discussion

  Among previously discussed structures, the more effective method is to control the effective
   dielectric constant by controlling the dimensions of antenna substrate, because this method;
  Compact size
  Continuously tunes the resonant frequency
  Low actuation voltages
  Didn’t increase the antenna dimensions
  Low power dissipation
  Have not any effect of radiation pattern or polarization
  MMIC applications


  Continuous frequency tuning without degrading other parameters




  9
3. Proposed Structure
 A schematic view of structure

  Silicon is selected as lower
           segment:
 MMIC applications
 Compact size
 Lower bandwidth
 Losses caused by silicon
  conductivity


 Patch size: 3×3mm2
 Suspended silicon
  membrane:4×4mm2
 εr of suspended silicon membrane:
  11.9
 Initial air gap between the patch and
  feed line: 114µm
  10
3. Proposed Structure

Governing equation in microstrip antenna design:

               v0
fr 
       2( L  L)  reff                                                              31

                                                                                      30




                                                           Resonant Frequency (GHz)
                                                                                      29

                                                                                      28

                                                                                      27

                                                                                      26

                                                                                      25

                                                                                      24

                                                                                      23

                                                                                      22
                                                                                       100   200           300         400   500
                                                                                                   Air Gap Height (um)
        Conceptional operating principal of the antenna.   Resonant frequency shift of the antenna versus the air
                                                                          gap height variations.




  11
3. Proposed Structure
Effect of Initial Air Gap on Tuning Range and bandwidth of the Antenna
                                                            Simulation results of the antennas with different initial air gaps

                                                                        Up-state Maximum Frequency shift




                                                           Antenna
       50µm                                                    Initial
                                                                       operating downward         (GHz)
       downward                                                air gap
                                                                       frequency deflection (with return loss
       deflection                                               (µm)
                                                                         (GHz)     (µm)     better than 10dB)
                                                           (1)   500     29.96      350             5.66
                                                           (2)   280     26.66      120             2.35
                                            Initial air    (3)   120      23.11      50             2.62
                                            gap =120µm
                                                                                      6

                                                                                     5.5
                                                                                                    5.74%
                                                                                      5
       Resonant frequency shift of the 23.11 GHz antenna



                                                                     Bandwidth (%)
               by decreasing the air gap height.                                     4.5

                                                                                      4

        Based on simulation results, the                                             3.5
   initial air gap of the proposed antenna
                                                                                      3
   system is decided to be around 120µm.
                                                                                     2.5
                                                                                       20     40    60     80    100 120 140    160   180
                                                                                                         Air Gap Height (um)
                                                                                          Effect of the initial air gap height on bandwidth
  12
3. Proposed Structure
Electro-Thermal Micro-Actuator Configuration
                                                           DIMENSIONS OF THE ELECTRO-THERMAL MICRO-
                                                                           ACTUATOR.
                                                             Geometrical        Hot    Cold   Shuttle
                                                           parameters (µm)     Arm     Arm
                                                                Length                430       400        354
                                                                Width                  8         12         17
                                                               Thickness               2          4        4.95



                                                       MATERIAL PROPERTIES OF THE ELECTRO-THERMAL MICRO-
                                                                           ACTUATOR.

                                                             Material properties            Silicon   Poly Silicon
                                                             Young modulus ( GPa)            185          162
                                                                 Poisson ratio               0.28         0.22
                                                               Density (Kg/m3)               2329        2320

                                                           Thermal expansion (1/Cº)         2.6e-6       3.6e-6
                                                             Thermal conductivity
                                                                                             149          41
                                                                 (W×C-1/m)
  The schematic view of the proposed electro-thermal
                                                               Resistivity (Ω.m)              1e3        20e-6
                   micro-actuator.


 13
            3. Proposed Structure
            Electro-Thermal Micro-Actuator Configuration
                                23

                                     Up-state position,
                               22.5 Frequency =22.61GHz                                                                    8
                               14
                                    3µm downward deflection,
Power Dissipation (mW) (GHz)




                                                                                                                           7
                               12 Frequency = 22.17GHz
                                 22




                                                                                                Downward Deflection (um)
               Frequency




                                                                                                                           6
                               10
                               21.5
                                                                                                                           5
                                8
                                21                                                                                         4
                                6
                                                                                                                           3
                               20.5
                                4 100     102    104    106   108    110     112     114
                                                   Air Gap Height (um)                                                     2
                                2 Frequency shift of the proposed antenna respect to air    Thermal distribution over the actuator for a 1.5V applied voltage
                                                  gap height variations.                          1

                                0                                                0
                                 0       0.5    1.5
                                                 1      2    2.5  3    3.5   4 RESPECTIVE POWER DISSIPATION AND APPLIED VOLTAGE
                                                                                  0          1          2          3          4
                                               ESPECT Voltage (V)
                                 TUNING RANGE RApplied TO DOWNWARD DEFLECTION                  Applied Voltage (V)
                                                                                            FOR A 3µM DEFLECTION
                                      Power dissipation curve respect to applied voltages                      Downward deflection curve respect to applied voltages
                                      Downward Deflection (µm)        Tuning range (MHz)       Downward Deflection                    Applied Voltage   Power dissipation

                                                 3                            440                                              3 µm       1.5 V              2mW
                               14
3. Proposed Structure
Mechanical Considerations


 The suspended silicon membrane is mechanically fixed through a number of suspension
  systems.

 Suspension systems are a combination of thermal actuators and meandered springs.

 The mechanical functionality and power dissipation of the antenna structure is mainly
  dependent on the number of suspension systems connected to the silicon membrane.


                                                            NATURAL FREQUENCIES OF ANTENNA STRUCTURE FOR
                                                          DIFFERENT NUMBERS OF SUSPENSION SYSTEMS CONNECTED
                                                                         TO THE SILICON MEMBRANE.


                                                           Number of suspension           First natural
                                                                systems                 frequency (KHz)
                                                                     4                        0.913
                                                                     6                        1.17
      Z-orientation mechanical natural frequency of the
                         structure.                                  8                        1.37

 15
3. Proposed Structure
Proposed Fabrication Process Flow




 16
3. Proposed Structure
Antenna Simulation Results

 RETURN LOSS OF THE ANTENNA


                                                                     Simulation results of return loss for
                                                                        selected actuation voltages


                                                                    Actuation
      3µm deflection,                                                               0        1.18      1.5
                                                                   Voltage (V)
      Voltage=1.5V
                                                                   Deflection
                                                                                    0         2         3
                                                                     (µm)
        2µm deflection,                                            Operating
        Voltage=1.18V                                              Frequency      22.61     22.42    22.17
                                                      Up-state,      (GHz)
                                                      Voltage=0V   Return Loss
                                                                                  -26.26    -23.67   -20.76
                                                                      (dB)
                                                                   Bandwidth
                                                                                   1.34      1.30     1.27
                                                                     (GHz)

         Return loss of the antenna for various applied voltages

 17
3. Proposed Structure
Radiation Patterns for Total Gain at E- and H-Planes
Discussion

    Thermal actuators are choose as driving mechanism in order to operate at
     voltage levels compatible with CMOS circuitries.
    The tuning range of the proposed antenna can also be increased by further
     downward deflection of the patch by thermal actuators.

    Simulation results show that the bandwidth of the antenna in up-state position
     is about 1.34GHz, and 1.27GHz in down-state (3µm deflection from up-state)
     position.
             Up-state                            2µm downward deflection                          3µm downward deflection
   As discussed before,
 Operating frequency 22.61GHz power dissipation and mechanical stability conflict with
                                 Operating frequency 22.42GHz   Operating frequency 22.17GHz
                                   number of
      each other, increasing the Broadside Gain suspension systems both enhances the
   Broadside Gain     5.82dB                          5.92dB      Broadside Gain     5.94dB
       mechanical for total gain at E- and dissipation.
      Radiation patternstability and powerH-planes: (a) Up-state, (b) 2µm deflection, (c) 3µm deflection.


    A new structure is proposed to overcome this shortcoming.
 Mirzajani, H., Nasiri, M., Ghavifekr, H. B. (2012) A New Design of MEMS-Based Wideband Frequency Reconfigurable Microstrip Patch
  Antenna. 8th International Symposium on Mechatronics and its Applications (ISMA), Sharjah, UAE, pp. 1-6
 Mirzajani H, Nasiri M, Ghavifekr H B (2012) A Novel MEMS-based Wideband Frequency Tunable Microstrip Patch Antenna. In: 20th
  Iranian Conference on Electrical Engineering (ICEE), 15-17 May, pp 1383-1387
 18
3. Proposed Structure
Discussion


                  Tuning   Operating
                                       Actuation        Power       Publication
      Reference   Range    Frequency
                                       Voltage (V) Dissipation (mw)   Year
                  (MHz)      (GHz)
         [1]       300       16.05        11.9               -             2007
         [2]       270       16.91        165                -             2007
         [3]       1020      16.8                            -             2004
                   350       10.57
         [3]                                                 -             2009
                   1000       8.7
                   7.42      2.45
         [5]                             ≈ 200               -             2010
                   7.70      5.80
         [6]       930       7.73                            -             2012
         [7]       330       22.19        2.65      6.78 (each actuator)   2012
      This work    440       22.61        1.5        2 (each actuator)     2012



 19
 3. Proposed Structure
 A schematic view of structure

 The idea is to etch
  embedded slits and
   slots on antenna
   patch and silicon
      membrane
  without degrading
     antenna EM
     performance.




                   Return loss of the antenna for different air gap heights
   20
3. Proposed Structure
Effect of etching slits and slots on EM performance of the antenna
Antenna is designed in fundamental mode TM 10




                                                                                 0.3mm
                                                     L




                  v0          L= distance that is traveled by surface currents,
   fr                        Manipulation of L, directly influences the operating
          2( L  L)  reff
                              frequency and bandwidth of the antenna.

  21
3. Proposed Structure
                                     mechanical performance of the
Effect of etching slits and slots on EM performance of the antennaantenna

   Creating embedded slots close to radiating 6.52 disorder TM 30 ℅ mass
 Decreasing the effective mass from 8.38 to edges mg, about 22.2mode of operation
 reduction.
   But the TM 10 is unchanged
                                                                    3mm




                                                            3mm
                                                                                   0.3mm


                                                                                1.1 mm


                                                                  Dimensions of patch
          Effect of mass on mechanical resonant frequency
             Decreasing the TM 30 operating frequency
  22
3. Proposed Structure
HFSS Simulation Results




               Actuation Voltage (V)        0      0.86    1.25
                    Deflection (µm)          0       1        2
               Operating Frequency (GHz)   15.12   14.87   14.62
                   Bandwidth (MHz)          220     220     200
                  Broadside Gain (dB)       3.12    3.17    3.19
 23
3. Proposed Structure

 Discretizing the
  silicon membrane in
  order to enhance
  downward deflection




  24
3. Proposed Structure


      Downward deflection of
 discretized membrane for a 1.6 V
           applied voltage




 Downward deflection of two central slices




               Number of thermal actuators              Natural frequency (Hz)
                             4          1.6V                      481

                             6                                   530
                                               Downward deflection of thermal actuators
                             8                                    585



 25
3. Proposed Structure



                             Frequency shift of the antenna for
         Zoomed out region        different air gap height




                                   Return loss of the
                                  antenna for different
                                    applied voltages

 26
3. Proposed Structure
HFSS Simulation Results




 27
3. Proposed Structure
A new design for antenna drive system



 Produces in-plane deflection
  parallel to substrate




                                            The schematic view of the proposed electro-thermal
                                                             micro-actuator.
       Chevron electro-thermal µ-actuator


  28
3. Proposed Structure

                                            Dimensions of the proposed structure
        Geometrical parameters                                                  Cold
                                                                Hot Arm                     Shuttle       Beam
                (µm)                                                            Arm
               Length                                             430           400          354          148
                Width                                              8             12           17           2
             Thickness                                             2              4          4.95          2
                                       25
            Downward Deflection (um)




                                       20


                                       15


                                       10


                                       5


                                       0
                                        0     0.2   0.4   0.6    0.8     1     1.2    1.4    1.6    1.8     2
                                                                Applied Voltage (V)

                 A schematic view of of proposed actuator
            Downward deflection curvethe the proposed structure
 29
3. Proposed Structure
                                      5


                                      4

             Power Dissipation (mW)
                                      3


                                      2


                                      1


                                      0
                                       0      0.2   0.4     0.6     0.8      1      1.2    1.4   1.6    1.8   2
                                                                  Applied Voltage (V)
                                             Power dissipation curve of the proposed structure




                                                          Applied           Power         Natural Frequency       Max Temp.
                                           Deflection
       Actuator                                           Voltage         Dissipation      (Hz) (4 Numbers of     Distribution
                                             (µm)
                                                            (V)             (mW)            suspension systems)       (C°)

       U-shaped                               10            1.6               2.4                 335                84.4
       Chevron                                10            0.8              1.46                 308                105
 30
4. Conclusion

   A new structure of frequency reconfigurable microstrip patch antenna based on
    microelectromechanical systems technology is demonstrated in this paper.


   Thermal actuators are choose as driving mechanism in order to operate at voltage
    levels compatible with today’s CMOS circuitries.


   The tuning range of the proposed antenna can also be increased by further
    downward deflection of the patch by thermal actuators.



   Thermal actuators are corrected in order to decrease the actuation voltage and
    power dissipation




 31
4. Conclusion

                    Tuning   Operating
                                         Actuation        Power       Publication
      Reference     Range    Frequency
                                         Voltage (V) Dissipation (mw)   Year
                    (MHz)      (GHz)
          [1]        300       16.05        11.9               -             2007
          [2]        270       16.91        165                -             2007
          [3]        1020      16.8                            -             2004
                     350       10.57
          [4]                                                  -             2009
                     1000       8.7
                     7.42      2.45
          [5]                              ≈ 200               -             2010
                     7.70      5.80
          [6]        930       7.73                            -             2012
          [7]        330       22.19        2.65      6.78 (each actuator)   2012
          [8]        440       22.61        1.5        2 (each actuator)     2012
      This design    1050      18.8         0.6       1.46 (each actuator)   2012



 32
5. Future Works
1. Using electro-static actuators instead of electro-thermal actuators,




  33
5. Future Works

2. Changing antenna radiation pattern

3. Changing antenna radiation pattern and operating frequency,




                Radiating               Patch              Radiating
                  edge                                       edge




  34
6. Publications
[1]. Hadi Mirzajani, Mahdi Nasiri and Habib Badri Ghavifekr, ‘A New Design of MEMS-Based Wideband
Frequency Reconfigurable Microstrip Patch Antenna’ 8th International Symposium on Mechatronics and its
Applications (ISMA), Sharjah UAE, pp. 1-6, April 2012. (IEEE Indexed).

[2]. Hadi Mirzajani, Mahdi Nasiri and Habib Badri Ghavifekr, ‘A Novel MEMS-based Wideband Frequency
Tunable Microstrip Patch Antenna’ 20th Iranian Conference on Electrical Engineering (ICEE2012), Tehran Iran,
pp. 1383-1387, May 2012. (IEEE Indexed).

[3]. Mahdi Nasiri, Hadi Mirzajani and Habib Badri Ghavifekr, ‘A Novel Micromachined Frequency
Reconfigurable Microstrip Patch Antenna Using Thermal Actuators’ Manuscript is accepted for publication in
proc. of 4th International Conference on Computer & Communication Engineering, Kuala Lumpur, Malaysia, July
3-5, 2012, in press. (IEEE Indexed)

[4]. Hadi Mirzajani, Mahdi Nasiri, Hamed Demaghsi and Habib Badri Ghavifekr, A Novel MEMS-Based
Electro-Thermally Driven More Mechanically Stable Structure for Frequency Tunable Microstrip Patch Antenna:
Design and Simulation’ Manuscript is under review in SPRINGER SADHANA - Academy Proceedings in
Engineering Sciences (ISI).

[5]. Hadi Mirzajani, Mahdi Nasiri and Habib Badri Ghavifekr, A new MEMS-Based mechanically driven
frequency tunable microstrip patch antenna’ Manuscript is under review in SPRINGER, Microsystem
Technologies (ISI).

[6]. Mahdi Nasiri, Hadi Mirzajani, Ehsan Atashzaban and Habib Badri Ghavifekr, ‘Design and simulation of a
micromachined frequency reconfigurable microstrip patch antenna’ Manuscript is under review in SPRINGER,
Wireless Personal Communications (ISI).
  35
 References
[1] Emre Erdil, K. T., Mehmet Unlu, Ozlem Aydin Civi, and Tayfun Akin, "Frequency Tunable  Microstrip
Patch Antenna Using RF MEMS Technology." IEEE transactions on antennas and propagation 55(4): 1193-1196,
April 2007.

[2] Ramadoss, R. J. J. a. R., "A MEMS-based Electrostatically Tunable Circular Microstrip Patch    Antenna"      J.
Micromech. Microeng. 17: 1-8, 2007.

[3]        R. Al-Dahleh, C. Shafai, and L. Shafai, “Frequency-agile Microstrip Patch Antenna  Using         A
Reconfigurable Mems Ground Plane” Microwave And Optical Technology Letters / Vol. 43, No. 1, October 5 2004

[4] Kagan Topalli, Emre Erdil, Ozlim Aydin Civi, Simsek Demir, Sencer Koc, Tayfon Akin,      "Tunable
Frequency RF MEMS Rectangular Slot Ring Antenna " Sensors and Actuators A 156:     373- 380, 2009

[5] Hyun Il Kang, Jong Tae Kim, Joon Tae Song, “Frequency Agile Antennas Based on Aluminum Nitride
Ceramics. “ Current Applied Physics 10: 642-645, 2010.

[6] Vahid Sathi, Nasrin Ehteshami, Javad Nourinia, “New frequency-reconfigurable microstrip     antenna
composed of organic semiconductor polymer” Organic Electronics, Volume 13, Issue 7, July 2012, Pages 1192-1196

[7]   Hadi Mirzajani, Mahdi Nasiri and Habib Badri Ghavifekr, "A Novel MEMS-based Wideband Frequency
Tunable Microstrip Patch Antenna. " Manuscript is accepted for publication in ICEE 2012.

[8]    Hadi Mirzajani, Mahdi Nasiri and Habib Badri Ghavifekr, “A new design of MEMS-based wideband
frequency reconfigurable microstrip patch antenna” Mechatronics and its Applications (ISMA), 2012 8th International
Symposium on, DOI : 10.1109/ISMA.2012.6215169

   36
Thank You For Your Attention!

				
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