Transcript Final Presentation

By Dan Pulito and Jason Blackman
Motivation
 Kodak desired an environment in which data rate and
power measurements were capable of being measured
 Extended in order take automated antenna
measurements
 Finished design is to provide an environment for other
senior design teams to test their wireless projects for
antenna radiation and signal power.
Overview, What has been done?
 An aluminum box was donated by Kodak and adjustments were
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made to prevent RF radiation from leaking from outside to inside
and vice versa
Calculations were done in order to determine if the size of the
box was adequate for the application and also to determine
antenna placement
The box was then padded with RF absorbent foam
A platform and motor were implemented to perform antenna
measurements
Software was written to synchronize motor angle and
measurements taken on a spectrum analyzer
A known antenna with known gain was measured to calibrate
loss in the system and a sample antenna was measured
Project Requirements
Engineering Specifications
Engr.
Spec. #
ES1
ES2
ES3
ES4
ES5
ES6
ES7
ES8
ES9
Importance
1
1
1
1
2
2
3
1
1
Specification (description)
Leakage Out of the Box
Leakage into the Box
Absorption of Material
Additional Power Readings Due to Reflections
Frequency range of box
Frequency range of receive antennas
Overall Weight of Box
Area Effected by EMI leakage from USB cables
Loss Connection loss
Unit of
Marginal Value
Measure
dB
<-25
dB
<-25
dB/Reflection
> 15
dB
< -20
GHz
2-3
GHz
2-3
Pounds
<50
Inches
<12
dB/Connection
<2
Ideal
Value
<-60
<-60
> 30
< -50
1-6
1-6
<20
<3
<1
Tasks Added at DDR
Engr.
Spec. #
ES10
ES11
ES12
ES13
Engr.
Spec. #
ES14
Importance
1
1
1
1
Feature
Incorporation of a Motor for Angle Measurements
Synchronize Measurements Between Motor Controller and Spectrum Analyzer
Calibrate Out Losses due to Free space and Cables
Map Data into Normalized Radiation Pattern
Importance
1
Specification (description)
Minimum Angle Step
Unit of
Measure
Degrres
Marginal Value
≤1
Ideal
Value
≤0.5
Size and Position Analysis
 The analysis of the position of the antennas, and the
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verification that the size of the box meets the requirements
was done in the DDR
The box dimensions are: 9”x 27” x 37”
It was found that at a frequency of 2.4 GHz, the antenna
separation should be at minimum 21 inches
To reduce skipping waves, the antennas should be placed
very close to the minimum distance based on the far-filed
criteria so as to reduce shallow angles
Finally, to meet the criteria, the antennas were placed 4.5
inches from the bottom, 13.5 inches from the two side rails,
and 21 inches apart.
Platform (Thank You Professor Slack)
•A Platform was built to encase the motor and also to lift the box up in order
to allow the motor to be installed from beneath the box.
•37”x 24”
•Features compartment for the motor
•Two wooden pieces and L-brackets hold the box in place while on the
platform
Wideband Antenna
Return Loss
Ansoft LLC
PlanarEM1_1_2
0.00
ANSOFT
Curve Info
dB(S(1,1))
Setup_1 : Sw eep_1
-5.00
designed with a return loss
of -15 dB between 2 to 4.8
GHz.
 The design features two
resonances allowing a good
frequency response over a
wide range
 Utilizes a distinct patch
geometry as well as etching
in the ground plane
-10.00
-15.00
dB(S(1,1))
 A wideband Antenna was
-20.00
-25.00
-30.00
-35.00
-40.00
0.00
1.00
2.00
3.00
4.00
Freq [GHz]
5.00
6.00
7.00
Rx ANTENNA
Tx ANTENNA
•The antenna to be tested is initially
facing 90° to the right, where directly
facing the transmit antenna is 0°
STARTING POSITION
Rx Antenna
•It rotates counter clockwise in steps of
about 1°
VERTICAL PLATFORM
Tx ANTENNA
•At each step, a power measurement is
taken from the spectrum analyzer
HALFWAY POSITION
•This continues for half of a revolution,
until the antenna is facing the opposite
direction that it started in
Tx ANTENNA
VERTICAL PLATFORM
Rotating Platform
VERTICAL PLATFORM
Rx ANTENNA
ENDING POSITION
Motor Controller
MOTOR
•The PC (LabVIEW) sends a signal (via the
DAQ) to the MCU telling it to rotate the
motor
•The MCU sends a serial command to the
motor controller to get the motor to rotate,
then monitors the encoder feedback until
the next step is reached
•The MCU then signals to the PC (via the
DAQ) that the next step has been reached
ENCODER
MCU
MOTOR
CONTROLLER
DAQ
•The PC acquires the power reading from
the spectrum analyzer and displays it
graphically and also writes it to a text file
•The MCU signals to the PC when a full
cycle (180°) is complete
PC
SPECTRUM
ANALYZER
LabVIEW
 The instrument, frequency,
span and ref level are selected
before running
 The full span is displayed on
the upper smaller graph at
each step
 The peak power value for each
step is plotted on the lower
graph
 After a full cycle is complete, a
text file with all of the peak
power measurements is saved
for use in Matlab or Excel
Project Status
 The programming of the motor and the spectrum analyzer are
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synchronized, meaning, the Tektronix Spectrum analyzer is
programmed to make a measurement every time the motor makes a
movement
The antenna has been designed and simulated in software. The design
of the patch has been etched and four samples were produced.
However, due to the manufacturing process, the ground plane has to be
etched by hand. This has yet to be completed.
The four aluminum plates to cover the preexisting holes have been
machined and are attached to the box
The chamber has been padded with RF absorbent foam
Tests comparing the unaltered chamber against the modifications have
been completed and the results are tabulated
Test Plan
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The Transmit antenna was powered with the
Atheroes software via a USB cable
The transmit antenna was placed at the
geometric center of the box
The Transmit antenna pattern is
omnidirectional, allowing antenna position to be
ignored
The transmit antenna was placed upright as well
as the receive antenna, thus positioning the
antennas to be polarization matched
The transmit antenna was secured on a
cardboard platform to prevent any electrical
properties of the stand from interfering with test
measurements
The lid was then secured and measurements
were taken for each side of the box. Each time,
the antennas were placed one meter apart.
Measurements were taken with no modifications
to the box in order to compare and quantify any
solutions that were implemented to the box
Isolation Test results
Side
1
2
3
4
Free Space(dBm)
-35
-35
-35
-35
Peak Power Measurements 1m from Transmitter
Original Box (dBm) Box w/ Foam (dBm) Box w/ Foam and Covers (dBm)
-52
-79
-43
-71
-48
-67
-93
-39
-89
Isolation
Original Box (dB)
Side
1
2
3
4
Side
1
2
3
4
Box w/ Foam (dB)
17
8
13
4
Isolation (from outside to in)
Box w/ Foam and Covers (dB)
35
35
31
39
Box w/ Foam and Covers (dB)
32
44
36
58
54
Unmet and met Specifications
Specification (description)
Marginal Ideal Value Marginal
Ideal Value
Value Met
Met
Value
Comments
Leakage Out of the Box
Leakage into the Box
Absorption of Material
Additional Power Readings Due to Reflections
Frequency range of box
Frequency range of receive antennas
Overall Weight of Box
Area Effected by EMI leakage from USB cables
Connection loss
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
No
No
Yes
No
No
Yes
No
Yes
Incorporation of a Motor for Angle Measurements
Yes
-
The motor has been implemented and the code to control
the motor has been completed
Synchronize Measurements Between Motor
Controller and Spectrum Analyzer
Yes
-
The motor controller and the tektronix spectrum analyzer are
syncronized with labview
Calibrate Out Losses due to Free space and Cables
No
-
An antenna with a standard gain is required to do this. More
time is required to finish.
Map Data into Normalized Radiation Pattern
No
-
Calibration Must be performed first
Minimum Angle Step
No
No
<-25
<-25
> 15
< -20
2-3
2-3
<50
<12
<2
≤1
<-60
<-60
> 30
< -50
1-6
1-6
<20
<3
<1
≤0.5
Secured lid and shielded USB cable will improve isolation
Unable to devise a test plan to evaluate
Based on seperaton of antennas, 2-6 GHz can be achieved
Antenna has been designed for 2-4.8 GHz
USB cable acted as an antenna, poor shielding
Friction, creates energy loss which leads to unpredictable
motor displacement
Additional Suggestions to Improve Isolation
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Vast Majority of leakage problems occurred
because the lid did not make a flush contact
to the edges of the wall.
A cross section of a possible solution is
shown in the upper right
The lid and the wall interlock with each
other in addition to being padded with
gasket material
The JRE 1618 shown here implements this
solution
Latches should also be used to fasten the lid
down on the box
Another source of poor isolation was the
USB cable.
The USB cable was picking up the
transmitted signal and acting as an antenna
outside the box
A USB filter can be used, but performance
usually deteriorates after 1 GHz
Thus, the outside shield of the cable must
somehow be completely grounded to the box