2014 06 17 Antenna - The Ohio State University

Report
Antenna Design Progress
Chi-Chih Chen
Research Associate Professor
Domenic Belgiovane
Graduate Student
The Ohio State University
ElectroScience Laboratory
Electrical and Computer Engineering Department
1330 Kinnear Road, Columbus, OH 43212
TEL: (614) 292-3403, FAX: (614) 292-7297, [email protected]
1
 Antenna Design
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Current antenna is 36 inches tall
10 dB gain across 500 MHz to 2 GHz bandwidth
Impedance between 150-180 Ω, but should be uniform across frequency bandwidth.
 Antenna Feeding Network
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Current design offers good performance across the frequency bandwidth.
Short board allows for cheap fabrication.
Impedance transforming transmission line (50Ω to 170Ω) Fabrication and testing to be
completed.
 Deploying Mechanism
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
Some possible design have been presented .
No current final design has been determined.
 Antenna Structure
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ABS material for use of Radome
Deformation should have little affect on gain pattern.
Large amount of stress at conical base may need additional consideration when mounting
to deployment base.
2
 Move towards Prototyping Structure
and Deployment Design
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
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Determine suitable material for antenna
structure.
Study Viable options for mechanical deployment
Fly on airplane to as preliminary test
 Design Antenna Feeding Network
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
Impedance transforming transmission line
 50 Ω to 170 Ω tapered line
Balanced line output to feed antenna
 Fabrication and Testing of Antenna
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
Fabrication of feed network
Antenna gain pattern measurements
Feeding
Network
Conical
Spiral
Antenna
3
•
Microstrip tapered line to balanced parallel strip
•
Shorter PCB will allow for cheap in-house
fabrication
•
Provides good S11 and S21 across the frequency
band
10”
Port 1
170Ω
Port 2
50Ω
3.3”
193mil
Top
View
1.93”
40mil
0.2”
Bottom
View
Rogers, RT/Duroid 5880
εr = 2.20
tanδ = 0.0009
t = 17μm
h = .062 in
4

Yield stress of ABS:10 MPa (very minimum possible value)

Predicted stress due to air resistance will not cause the ABS to fail

Magnitude of pressure applied to front surface area: 4.6 kPa

Stress is distributed evenly across the face
Direction of air flow
MPa
4 mm thick
Conical Radome
5
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
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These renderings of deformation are purposefully very exaggerated
in order to show regions of slight indentation and protrusion
The maximum displacement is experienced at the tip of the cone
Displacement will likely not have an effect on the Antenna gain
Pattern
Direction of air flow
mm
6
Air Cylinder Concept
Considerations for Antenna deployment
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
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Pivoting Mechanism

Deployment follows air drag
Low Profile

Close to fuselage surface

Total footprint approximately
antenna diameter.
Electronic Motor controlled

Double acting air-cylinder

Scissoring arm extension

Crank window opener
Weather and Temperature resilient
Crank Window Hinge
Antenna
Direction of air
flow
Deployed
Position
Air Cylinder
Transition
Scissoring Arm
Non-Deployed
Position
7
 Antenna Design


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Determine method for antenna fabrication.
Study affects of ABS Radome on antenna gain pattern.
Simulate effects of connecting the feeding network to the antenna.
Finalize and prototype antenna design.
 Measure Gain pattern and Impedance
 Reconfigure feed network impedance accordingly
 Deploying Structure
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Obtain ABS radome structure.
Finalize and build deploying mechanism.
Determine placement on fuselage.
Mount and test deployment on aircraft
 Finalize the Design

Combine Antenna and Mechanical designs
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