Antennas -- in 60 Minutes or Less!

1 / 48

# Antennas -- in 60 Minutes or Less! - PowerPoint PPT Presentation

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

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Antennas -- in 60 Minutes or Less!' - kennan

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### 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
• Directivity
• Gain
• Side Lobes
• Polarization
• Near Fields
• Mutual Coupling
• Specific Absorption Rate (SAR)
• Input Impedance (matching)
Dipole Antenna

Current distribution

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

Direction of Maximum

Direction of Maximum

Of an ISOTROPIC

Exist)

Directivity = Pmax dipole / Pmax Isotropic = 1.67

Gain = Directivity * Efficiency

3dB (1/2 Power

Point)

Half Power Beam Width

(HPBW)

Half Power Beam Width (HPBW)
Monopole Antenna

Monopole

Helix

Ground

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

Specific Absorption Rate (SAR)

FCC (ANSI/IEEE) Regulation

SAR (1g average) <1.6 W/kg

Cellular Telephones

- 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

SAR Distributions - 835 MHz (adult, 10 year old, 5 year old)

10 year

old

5 year

old

From: Gandhi, Lazzi, Furse, IEEE Trans. MTT

44(10) 1996

Folded Dipole

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

From: http:// www.centurion.com

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

N

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

Absorption’’ by Gert Frolund Rendersen, Jorgen Bach Andersen

|Reflection Coefficient|

= (Zo – ZL)/(Zo+ZL)

Zo=50 ohms

R=50 ohms?

Resonant

Frequency

X

PIFA ImpedanceZ = R + jX

|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

• 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

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

Reflector (Dish) Antenna

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

Arecibo Observatory -- Puerto Rico

Arecibo Observatory

GPS Antennas

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

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

constructively or destructively

Array interaction is necsessary.

From: http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/pat1.gif

Antenna Arrays

More Elements:

Higher Directivity

Sidelobes

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

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

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

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

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 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

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

HAARP -- Feed Sytem

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

HAARP/images/ant/tpile.jpg

HAARP -- Matching Networks

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

Corner Reflector Antenna

Reflector acts like

A “mirror” and produces

Virtual antennas.

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

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

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: