Panel Antenna - Senior Design
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Transcript Panel Antenna - Senior Design
Design Review: November 17,2011
Team Members: Allan Davis
Carlos Gonzalez
Cooper McBride
Objective
Design, fabricate and test a 900-Mhz
directional panel antenna for Schweitzer
Engineering Laboratories
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Applications
Radios provide comm channels for electric utility
protection, monitoring, and control
Economical alternative to fiber-optic cable
Backup primary protection channels
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Other Uses
Oil and gas pipelines and refineries
Water and wastewater treatment facilities
Fire and security alarm remote monitoring
Many more possible applications of wireless
communications for critical infrastructure
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What SEL Needs
An antenna that will have performance similar to a 5-
element Yagi antenna
The antenna will be used with the SEL-3031 transceiver
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Why a Panel Antenna?
SEL is currently selling directional Yagi antennas
An example of a 5-element Yagi is shown here
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This is a panel antenna made by the same company
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Panel Antenna Pros:
Lower cost than Yagi
Compact package
Ease of installation
SEL can manufacture a panel antenna using existing
facilities and equipment
Panel Antenna Cons:
Can’t increase directivity by adding elements as with Yagi
More ways for material inconsistencies to affect
performance
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Specifications
Directional
Vertical or Horizontal Polarization
Gain: ≥8 dBi
HP Horizontal Beamwidth: 45°
HP Vertical Beamwidth: 65°
Operating Frequency Range: 900-930 MHz
~ 3% Bandwidth
VSWR: ≤1.5:1
Characteristic Impedance: 50 Ω
Designed Using Printed Circuit Board Technology
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Example Radiation Patterns
Dipole
Yagi
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Current Design - Bowtie
This is a type of planar dipole antenna
θ0 is called the opening angle
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Bowtie Formulas
Characteristic impedance*
ZC = ln[cot(θ0 /4)]
Length*
L = 0.5 λ0 /(εeff)1/2
Effective dielectric constant*
εeff = 0.5(εr + 1) + 0.5(εr – 1)(1 + 10 d/W)-0.555
We plan to use FR-4 substrate
εr ~ 4.0-4.8 (decreases as frequency increases)
d is typically 1.6 mm, but other thicknesses available
*Source: C. Guo and R. Liu. (2009, June). A 900MHz shielded bow-tie antenna system for ground
penetrating radar. [Online]. Available:
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5550125&tag=1
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Possible Design Options
Edge cutting can be used to increase bandwidth of
bowtie and decrease physical size
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Another type of radiating element
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Metal Patch antenna
Gain not very high
Not very robust
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Design Challenges
How much gain can we get?
Feeding the antenna
Impedance matching
Determining spacing between PCB and backplate
Correctly interpreting simulation results
Simulation will require a lot of trial and error
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Impedance Matching
Want to match impedances to minimize transmission
line reflections from antenna toward radio
Max Power Transfer
Low reflection coeff. Low VSWR
This can be done both by changing antenna feed point
and by designing microstrip feedline impedance to be
Zmicrostrip = (ZcoaxZant)1/2
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Validation
Conduct impedance analysis using network analyzers
in Applied EM Waves Lab.
Time reserved for use of anechoic chamber at SEL
Use to make antenna pattern measurements
900-MHz feed & measurement system available
(antenna, signal generator, network analyzer, etc.)
Most of our measurements will be focused on figures
of merit, since SEL will have to have the antenna
characterized before production
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Software
Agilent Advanced Design System (ADS) with
Electromagnetic Professional (EMPro)
SEL is planning to incorporateADS Design Suite for
future projects
FEM Simulator
FDTD Simulator
Method of Moments
Impedance Analysis
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Progress
Currently a little behind according to our timeline
Issue with EMPro software
The software is unable to work correctly with standard
Intel Graphic Chipsets
Needed to order an Nvidia graphics card and install into
a laboratory computer
Works great now
In the future we will want to upgrade the RAM from
2GB to 4GB
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Working on getting tutorials to learn the software
Need to wait for the University license instead of our
trial version to obtain access to the tutorials
Have put in our order for the University license
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Budget
EMPro Software - $2000
Nvidia GT 430 Graphics Card - $85
Kingston 2GB RAM - $25
N-Connectors - $4 Each
PC Board and metal back plate
Provided by SEL
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Schedule
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Questions?
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