Antennas -- in 60 Minutes or Less!

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Antennas -- in 60 Minutes or Less!

• Cynthia Furse
• Department of Electrical and Computer Engineering
• University of Utah
• cfurse_at_ece.utah.edu

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Antennas 101

• Size / current distribution
• Radiation Pattern (farfields)
• Directivity
• Gain
• Side Lobes
• Polarization
• Near Fields
• Mutual Coupling
• Specific Absorption Rate (SAR)
• Input Impedance (matching)
• Link Budget

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Dipole Antenna
Current distribution
Fromhttp//www.qth.com/antenna/dipole.gif,plot.gi
f
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Radiation Pattern
Direction of Maximum Dipole Radiation
Direction of Maximum IsotripicRadiation
Radiation Pattern Of an ISOTROPIC Radiator (that
doesnt Exist)
Directivity Pmax dipole / Pmax Isotropic
1.67 Gain Directivity Efficiency
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Why do we care about Gain? Link Budget
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Half Power Beam Width (HPBW)
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(No Transcript)
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Monopole Antenna
Capacitive Load
Monopole
Helix
Ground
Fromhttp//www.letstalk.com//Images/5-a.gif
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Specific Absorption Rate (SAR)
FCC (ANSI/IEEE) Regulation SAR (1g average) lt1.6
W/kg
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Cellular Telephones
SAR Distribution in Adult - 835 MHz - Simplified
Phone Model - l /4 antenna
Pandit,McDermott,Lazzi,Furse,Gandhi, Electrical
Energy Absorption in the Human Head, presented
at IEEE Visualization 96, S.F., CA 1996
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SAR Distributions - 835 MHz (adult, 10 year old,
5 year old)
10 year old
Adult
5 year old
From Gandhi, Lazzi, Furse, IEEE Trans. MTT
44(10) 1996
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Folded Dipole
Fromhttp//www.qth.com/antenna/fdipole.gif
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Monopole Antenna above Ground Dipole Antenna
Ground
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MEANDER LINE ANTENNAS
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RADIATION PATTERN OF MEANDER LINE ANTENNA
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Microstrip Antenna(Slot of Same Size would give
identical results
From http// www.centurion.com
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Genetic Algorithm

• Choose Gene Parameters
• Randomly create population
• Survival of the Fittest
• Gene Crossover and Mutation
• Statistically Optimal

N
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Planar Inverted F Antenna (PIFA)
From FDTD Analysis of PIFA diversity antennas
on a hand-held transreceiver unit by Michael A.
Jensen and Yahya Rahmat-Samii
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From Integrated Antennas for Hand-held
Telephones with low Absorption by Gert Frolund
Rendersen, Jorgen Bach Andersen
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PIFA ImpedanceZ R jX
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(No Transcript)
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CAPACITIVELY LOADED PIFAs

• USUALLY LENGTH IS (L/4).
• IT REDUCES IT TO (L/8).

From A capacitively loaded PIFA for compact
mobile telephone Handsets by Corbett R. Powell,
Student Member IEEE, and R.D. Murch, Member IEEE
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DUAL BAND PIFA 1
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TRIPLE BAND PIFA
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PIFA WITH MEANDER LINES
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DIVERSITY ANTENNAS(ie. MIMO)
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BPFA
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BPFA RADIATION PATTERN
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COMPARISON of DTSA and MONOPOLE
SAR Distribution
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Loop Antenna
Fromhttp//www.downeastmicrowave.com/graphics/kbl
oop.gif
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Reflector (Dish) Antenna
From http//www.dssdirectv.com/chanmas1.jpg
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Arecibo Observatory -- Puerto Rico
From http//www.naic.edu/about/photos/aoviews/tes
cop.jpg
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Arecibo Observatory
Fromhttp//www.naic.edu/about/photos/aoviews/wide
ao.jpg
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GPS Antennas
Fromhttp//www.lowe.co.uk/gpsant.jpg
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Horn Antennas
From http//www.tmo.hp.com/tmo/datasheets/Images/
img-HP11966J-1lg.gif
From http//www.afcsat.com/CH14_MOT2.jpg
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Antenna Arrays
Two Elements -- Pattern adds constructively or
destructively Array interaction is necsessary.
From http//server5550.itd.nrl.navy.mil/projects/
HAARP/images/ant/pat1.gif
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Antenna Arrays
More Elements Higher Directivity Sidelobes
From http//server5550.itd.nrl.navy.mil/projects/
HAARP/images/ant/pat2.gif
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Scanning Antenna Array
Changing the phases on the element feeds can make
a scanning array.
Fromhttp//server5550.itd.nrl.navy.mil/projects/H
AARP/images/ant/pat3.gif
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Arrays
Fromhttp//www.qth.com/antenna/tiny2rl.gif
From http//cust.iamerica.net/dwhowell/yagimax.jp
g
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Polarization
E
E
E
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HAARP Observatory
HAARP (High frequency Active Auroral Research
Program) is to be a major Arctic facility for
upper atmospheric and solar-terrestrial research.
HAARP is being built on a DoD-owned site near
Gakona, Alaska.
Fromhttp//server5550.itd.nrl.navy.mil/projects/H
AARP/images/ohd.jpg
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HAARP Antenna ArrayCrossed Dipoles
The HF antenna system to be used for Active
Ionospheric Research at the HAARP site will
assist other facility instruments in the study
the overhead ionosphere. As a result, it too has
been designed to optimize or restrict the
transmission pattern to lie within a narrow
overhead region. To achieve this desirable
antenna pattern, the HAARP system uses an "array"
of individual antenna elements. The HAARP antenna
array is similar or identical to many other types
of directive antenna types in use for both
military and civilian applications including air
traffic control radar systems, long range
surveillance systems, steerable communication
systems and navigation systems.
Fromhttp//server5550.itd.nrl.navy.mil/projects/H
AARP/images/twr/pan2.jpg
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HAARP -- Feed Sytem
Fromhttp//server5550.itd.nrl.navy.mil/projects/
HAARP/images/ant/tpile.jpg
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HAARP -- Matching Networks
From http//server5550.itd.nrl.navy.mil/projects/
HAARP/images/ant/amu.jpg
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Corner Reflector Antenna
Reflector acts like A mirror and produces
Virtual antennas.
From http//www.northcountryradio.com/crfigs.htm
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Anything Radiates Fan-tenna
Fromhttp//www.qth.com/antenna/fanfull.gif
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So .. Where do we go from here with MIMO?

• Define Specifications (easier said than done)
• Maximum size
• Frequency and bandwidth
• What does the output of the antenna set need to
  be to achieve optimal communication?
• What antenna parameters affect that?
• What antenna is optimal?
• Parametric Studies
• GA or direct optimization

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Antenna References on the Web
General http//www.ee.surrey.ac.uk/Personal/D.Jef
feries/antennas.html GPS Antennas Lowe
Industries http//www.lowe.co.uk/antrev2.htmlhttp
//www.lowe.co.uk/antrev2.html Antenna
Calibration http//gracie.grdl.noaa.gov/GRD/GPS/P
rojects/ANTCAL/index.shtml Ham North Country
Radio http//www.northcountryradio.com/techtips.h
tm Antenna Elmer http//www.qth.com/antenna/anten
na.htm HAARP Observatory http//server5550.itd.n
rl.navy.mil/projects/HAARP/ant3.html Arecibo
Obervatory http//www.naic.edu/aboutao.htm