fitt smj pdf

8/3/2019 Fitt Smj PDF

1/23

Prof. S K Koul & Dr. Ananjan Basu

Surendra M Jain, 2008CRF3123

Thesis Title

Presented By

Supervisors


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Design of a conformal antenna, which is

Stat Stat Stat

Flexible & formable

Pattern reconfigurable

Uses MEMS switches

for mounting on nonplanar, non-rigid surfaces.


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Curvature effects on the antenna characteristics.

Design of 4-element antenna array(with delay line

phase shifters)

Array factor analysis and its validation.

Antenna Array using DMTL phase shifter


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Radius=500mm

Radius=35mm

Radius=13mm

ANNULAR RING

SLOT ANTENNA

RECTANGULAR

SLOT ANTENNA

RECTANGULAR

PATCH ANTENNA


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ANNULAR RING

SLOT ANTENNA

RECTANGULAR

SLOT ANTENNA

RECTANGULAR

PATCH ANTENNA


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ANNULAR RING

SLOT ANTENNA

RECTANGULAR

SLOT ANTENNA

RECTANGULAR

PATCH ANTENNA

Wide bandwidth antennas suit better as conformal antennas


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Array of Radiating ElementsArray of Radiating Elements

Phase Shifter Network- Switched LinePhase Shifter Network- Switched Line

Power Divider-Wilkinson Power

divider

Power Divider-Wilkinson Power

divider


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MEASURED RESULTS

ANNULAR RING SLOT ANTENNAWITH NO BEAM SHIFT

8.5 GHz, -11.6 dB


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ANNULAR RING SLOT ANTENNAWITH SHIFTED MAIN LOBE

8.5 GHz, -23 dB

MEASURED RESULTS


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d= spacing betweenelements

= Direction of interest

Array Factor = 1 + ej

+e j2

+ ej3

Where, = kd cos +

d cos


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d3 ={ (R sin - R sin )/ tan (90-)+ (R cos - R cos )}*cos

d2= 2R cos cos

d1 =[{R cos - R cos + (R sin - R sin )/ tan }*cos ] - (R sin -

R sin )* sin / tan


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RADIUS OF CURVATURE = 50 MM

MAIN BEAM

DIRECTION

PHASE SHIFTS FOR

ELEMENT #1 ELEMENT #2 ELEMENT #3 ELEMENT #490 0 0 0 0

74 0 -18.17 34.23 149.95

57.77 0 35.44 136.86 290.14


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RADIUS OF CURVATURE = 75 MM

MAIN BEAM

DIRECTION

PHASE SHIFTS FOR

ELEMENT #1 ELEMENT #2 ELEMENT #3 ELEMENT #490 0 0 0 0

68.51 0 23.28 93.66 205.282

60 0 51.54 146.93 28.23


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CURVED ANNULAR RING SLOT

ANTENNA, Curvature = 75 mm

MEASURED RESULTS

Relative Phaseshifts:0, -174, -281, -326


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OPERATING PRINCIPLE OF DMTL PHASE SHIFTER

MEMS Capacitances

Ground

Ground

Conductor

CMEMS

CMEMS

CMEMS

Transmission Line Sections

Zline Zline Zline


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MODELLING OF DMTL PHASE SHIFTER IN ADS

As the value of loading MEMS

capacitance increases, insertion lossincreases.For values of C

MEMS< 10 fF, the

change in phase is not verysignificant, though it keeps onincreasing with increasing value of

CMEMS.For values of CMEMS

> 150 fF, theinsertion loss becomes high andhence these values should beavoided.As the number of sections

increases, phase change is higher fora particular value of CMEMS.


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SIMULATION OF DMTL PHASE SHIFTER


18/23

CPW-FED 2 ELEMENT RECTANGULAR SLOT ARRAY


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CPW-FED 2 ELEMENT ARRAY WITH DMTL PHASE SHIFTER


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With a conformal array, analog phase shifter in the form

of DMTL phase shifter, curvature sensing coupled with

feedback mechanism for the phase shifter, we arrive at

a pattern reconfigurable antenna, using which beam

maxima can not only be steered in the desired direction

but can also be maintianed in that direction irrespective

of curvature variation.

During this work, MEMS bridges were simulated with

fixed capacitances. However, by use of actual MEMSbridge with varying actuation voltages, we can precisely

control and phase shift and hence the direction of beam

maxima.


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Successful Design of Conformal Antenna Array

Demonstation of use of DMTL phase shiter in antenna

arrays


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For Non Rigid Structures

DMTL phase shifters can prove useful in phased array

antenna systems.

Why phase shifers?

Conformal antennaitself can serve thepurpose of BEAMSCANNING.

Switch ON one

element at a time


23/23

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