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Antennas -- in 60 Minutes or Less!. Cynthia Furse Department of Electrical and Computer Engineering University of Utah cfurse@ece.utah.edu. Antennas 101. Size / current distribution Radiation Pattern (“far”fields) Directivity Gain Side Lobes Polarization Near Fields Mutual Coupling

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antennas in 60 minutes or less

Antennas -- in 60 Minutes or Less!

Cynthia Furse

Department of Electrical and Computer Engineering

University of Utah

cfurse@ece.utah.edu

antennas 101
Antennas 101
  • Size / current distribution
  • Radiation Pattern (“far”fields)
    • Directivity
    • Gain
    • Side Lobes
    • Polarization
  • Near Fields
    • Mutual Coupling
    • Specific Absorption Rate (SAR)
  • Input Impedance (matching)
  • Link Budget
dipole antenna
Dipole Antenna

Current distribution

From:http://www.qth.com/antenna/dipole.gif,plot.gif

radiation pattern
Radiation Pattern

Direction of Maximum

Dipole Radiation

Direction of Maximum

IsotripicRadiation

Radiation Pattern

Of an ISOTROPIC

Radiator (that doesn’t

Exist)

Directivity = Pmax dipole / Pmax Isotropic = 1.67

Gain = Directivity * Efficiency

half power beam width hpbw

3dB (1/2 Power

Point)

Half Power Beam Width

(HPBW)

Half Power Beam Width (HPBW)
monopole antenna
Monopole Antenna

Capacitive Load

Monopole

Helix

Ground

From:http://www.letstalk.com//Images/5-a.gif

specific absorption rate sar
Specific Absorption Rate (SAR)

FCC (ANSI/IEEE) Regulation

SAR (1g average) <1.6 W/kg

cellular telephones
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

slide11

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

folded dipole
Folded Dipole

From:http://www.qth.com/antenna/fdipole.gif

microstrip antenna slot of same size would give identical results
Microstrip Antenna(Slot of Same Size would give identical results

From: http:// www.centurion.com

genetic algorithm
Genetic Algorithm
  • Choose “Gene” Parameters
  • Randomly create population
  • “Survival of the Fittest”
  • Gene “Crossover” and “Mutation”
  • Statistically Optimal

N

planar inverted f antenna pifa
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

slide19

From: “Integrated Antennas for Hand-held Telephones with low

Absorption’’ by Gert Frolund Rendersen, Jorgen Bach Andersen

pifa impedance z r jx

|Reflection Coefficient|

= (Zo – ZL)/(Zo+ZL)

Zo=50 ohms

R=50 ohms?

Resonant

Frequency

X

PIFA ImpedanceZ = R + jX
slide21

|S11| = |Reflection Coefficient Γ|

(Less than half of the power is

Reflected within this bandwidth)

There will ALWAYS

Be a higher harmonic

Band. Must filter if

unwanted.

½ Power Bandwidth

capacitively loaded pifas
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

loop antenna
Loop Antenna

From:http://www.downeastmicrowave.com/graphics/kbloop.gif

reflector dish antenna
Reflector (Dish) Antenna

From: http://www.dssdirectv.com/chanmas1.jpg

arecibo observatory puerto rico
Arecibo Observatory -- Puerto Rico

From: http://www.naic.edu/about/photos/aoviews/tescop.jpg

arecibo observatory
Arecibo Observatory

From:http://www.naic.edu/about/photos/aoviews/wideao.jpg

gps antennas
GPS Antennas

From:http://www.lowe.co.uk/gpsant.jpg

horn antennas
Horn Antennas

From: http://www.tmo.hp.com/tmo/datasheets/Images/img-HP11966J-1lg.gif

From: http://www.afcsat.com/CH14_MOT2.jpg

antenna arrays
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

antenna arrays37
Antenna Arrays

More Elements:

Higher Directivity

Sidelobes

From: http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/pat2.gif

scanning antenna array
Scanning Antenna Array

Changing the phases on the element

feeds can make a scanning array.

From:http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/pat3.gif

arrays
Arrays

From:http://www.qth.com/antenna/tiny2rl.gif

From: http://cust.iamerica.net/dwhowell/yagimax.jpg

haarp observatory
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.

From:http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ohd.jpg

haarp antenna array crossed dipoles
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.

From:http://server5550.itd.nrl.navy.mil/projects/HAARP/images/twr/pan2.jpg

haarp feed sytem
HAARP -- Feed Sytem

From:http://server5550.itd.nrl.navy.mil/projects/

HAARP/images/ant/tpile.jpg

haarp matching networks
HAARP -- Matching Networks

From: http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/amu.jpg

corner reflector antenna
Corner Reflector Antenna

Reflector acts like

A “mirror” and produces

Virtual antennas.

From: http://www.northcountryradio.com/crfigs.htm

anything radiates fan tenna
Anything Radiates …Fan-tenna

From:http://www.qth.com/antenna/fanfull.gif

so where do we go from here with mimo
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
antenna references on the web
Antenna References on the Web

General: http://www.ee.surrey.ac.uk/Personal/D.Jefferies/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/Projects/ANTCAL/index.shtml

Ham:

North Country Radio: http://www.northcountryradio.com/techtips.htm

Antenna Elmer: http://www.qth.com/antenna/antenna.htm

HAARP Observatory: http://server5550.itd.nrl.navy.mil/projects/HAARP/ant3.html

Arecibo Obervatory: http://www.naic.edu/aboutao.htm