Antennas and Fundamental Parameters February 20, 2019...Definition of Antenna The guiding device or...

1

Fundamental Parameters and

Figures-of-Merit of Antennas

Constantine A. Balanis

Arizona State University

Tempe, AZ 85287 5

balanis@asu.

706

edu

Copyright©2016 by Constantine A. Balanis All rights reserved IEEE EMC, Phoenix, AZ, Section

March 20, 2019


March 20, 2019

AntennasSingle Elements and Arrays

'Electronic Eyes and Ears of the Worl

J

Antenn

ohn D.

d'

K

as:

raus

Antenna As A Transition/Transducer Device

Antenna

IEEE EMC, Phoenix, AZ, Section March 20, 2019

Copyright©2016 by Constantine A. Balanis All rights reserved

TE Horn Animation


March 20, 2019

TM Open Animation



TM Box Animation



2


March 20, 2019

Definition of AntennaAccording to the

:

"A means for radiating or receiving

According to t

rad

he :

"A means for radiating or receiving radio waves

io waves "

.

.

Webs

IE

ter'

EE S

s Dictio

tandard Definitions

of Terms for Antennas

nary

In other words, the antenna is the

between free-space and

a guiding device.

"

transitional

structure / transducer


March 20, 2019

Definition of Antenna

The guiding device or transmission line

may take the form of a coaxial line or a

hollow pipe (waveguide), and it is used

to transport EM energy from the transmitting

source to the antenna, or from the

In the former case, we have a

antenna and in the latter a antenna.

antenna

to the recei .

ver

transmitting

receiving



Definition of Antenna

In addition to receiving or transmitting EM energy,

an antenna in an advanced wireless communications

the radiation energy in some direction

system is usually required

s and

to optimize or accentuate

s

Thus the antenna must also serve as

directional devi

a

, in addition

it in

to a

.

rce adiating device

othe

.

rs

uppress



Thevenin EquivalentIn Transmission Mode



Horn Antenna And Its Equivalent

RL

Horn Equivalent



Types of Antennas

1. Wire antennas2. Aperture antennas3. Microstrip antennas4. Array antennas5. Reflector antennas6. Lens antennas7. Other Antennas for Mobile Units

3



Fundamental

Parameters



Coordinate Systemfor

Antennas



Coordinate System



Coordinate System



2 22

0 0 0 0

22

0 0

!

Area of Sphere s

Spherical Angular Limits

in

Area sin

Area 2 1 1 0 ! !

dA r d d

r d d

0

20



2 22

0 0 0 0

22

0 0

2 2

Area of Sphere s

Spherical Angular Limits

in

Area sin

Area 2 2 4

dA r d d

r d d

r r

20

0

4



ˆ ( , )a E H

ˆ ( , )a E H

ˆ ( , )r r ra E H

Spherical Electric and Magnetic Field Components

spherical

right hand

coordinate syst

ˆ

e

ˆˆ

ˆ

m

ˆ r

a

aa

aa



• Field Pattern:

A plot of the field (either electric |E| or magnetic |H|) on a linear scale

• Power Pattern:

A plot of the power (proportional to either the electric |E|2 or magnetic |H|2

fields) on a linear or decibel (dB) scale.

Amplitude Radiation Pattern


March 20, 2019

Linear ScaleN = 10 elementsd = /4 spacingHPBW = 38.64o

2-D Normalized Field |En| Pattern of a Linear Array

0.707 0.707

HPBW

|Er|

+ +

++

+ +-

--

--

Field Pattern(linear scale)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


March 20, 2019

2-D Normalized Power |En|2 Pattern

of a Linear Array

Linear ScaleN = 10 elementsd = /4 spacing

HPBW = 38.64o0.5 0.5

HPBW

+ +

-

--

Power Pattern(linear scale)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

|Er|2


March 20, 2019

dB ScaleN = 10 elementd = /4 spacing

HPBW = 38.64o

2-D Normalized Power |En| Pattern of a Linear Array in dB

-3 dB -3 dBHPBW

+ +

++

+ +

-

--

--

Power Pattern(dB)

-35

-30

-25

-20

-15

-10

-5

0

|Er|



Polar Pattern

x

z

y

Normalized FieldPattern (linear scale)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

First null beamwidth (FNBW)

Half-power beamwidth (HPBW)

Minor lobes

Major lobe

Side lobe

Minor lobes Back lobe

++

-

+-

-

+-

+ +-

5




0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

x

y

z

θ

ˆrE

E

E

Normalized 3-D Amplitude Field Pattern

of Linear Array

Linear Scale N = 10, d

2 2 2

ˆ( , , ) | ( , , )

ˆ + ( , , )

ˆ + ( , , )

| | | | | | | |

cr r r r c

c

c

r

E r a E r

a E r

a E r

E E E E



Polar (dB Scale): Two-Dimensional Pattern

- -

- -

+ +

Normalized FieldPattern (dB)

-35

-30

-25

-20

-15

-10

-5

0

(l=1.25)



Directivity D



0 rad

max max

radmax

10

10

0

0 0

, 4 ,

4

10log(dB) (dimensionless)

(dB) (dimensionles

[ ]

10 log s[ ])

o

D

D D

D

U U

U P

U U

U

D

D D

P



0

max

0

rad

directivity (dimensionless)

maximum directivity (dimensionless)

radiation intensity (W/unit solid angle)

maximum radiation intensity

radiation intensity of isotropic

radiated power (W)

D

D

U

U

U

P



DirectivityRealized

Gain

inP

Gain

radP

+inP

+inP

inP

6



Three-dimensional Directivity Pattern

Directivity(dimensionless)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

z

yx

D=1

D=1.67sin3( )

1.0

1.67

122.56°

1.67

57.44°


Two-Dimensional Directivity Pattern

D (dipole)=1.67sin3( )

D (isotropic)=1

57.44°

122.56°

57.44°

122.56°




rad 0 2

2rad 0

2rad 0

max 0x

0max

2

0 2rad

0

0ma

0

0

E

d

4 141.27 dimensionles

n

s

sin 1 n

x

.2

sin

B

ˆ

sin

s

ample 1:

Solutio

0

in

:

1. 38

7si

rW a Ar

P

AUD

P A

D

U

D

W

D

A

U r A

U A A



2

rad 0 2

ra

2

max 00

r

d 0

2 2rad 0

m

0

a

d

x 0

a

2

m x

0

0a 2

2

E

sinˆ

8

3

sin

sin

d

xample 2:

Solution:

1.761 dB

l4 4

1.5 imension ess8 3

sin 1.5sin

rW a Ar

P

A

U AD

P

D

A

U r W A

U U A

D

D



Three-Dimensional Normalized Radiation Patterns

0

2 20

0

0

1.27 1.038 dB

1.5 1

sin

sin 1.5sin

.761 d

1.

B

27sin

D

D D

D

D

D



7



0

0

2 2

o o

o o

0

0

12 11 1 2

0

1

1

0

0

1.5sin 1.5sin 1

1sin sin (0.667)

1

(isotropic) : 51.94 128.06

(i

1.27sin 1

1sin 0.

sotropic) : 54.

7871.27

s

.5

sin (0.8165) 54.7

74 125.26

in (0.787) 51

4

.94

D D

D D



Approximate Formulasfor

Directivity



Kraus Formula

01 2 1 2

2

01 2 1 2

2

1 2

0 0

1 2

4 4 41, 253

4 1804 41, 253

, sin

A r r d d

r r d d d d

A n r r

D

D

F d d



0 1 2

0 2 2 2 21 2 1 2

0 2 21 2

1 1 1 1

2

32ln 24 22.18

Arithmetic mea

1

72,

n

815A r r r r

d d

D D D

D

D

Tai & Pereira Formula




0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

x

y

z

θ

ˆrE

E

EN = 10 elementsd = /4 spacingHPBW = 38.64o

FNBW = 73.8o



01 2 1

0 2 2 21 2

2

0

0 21 2

72,8

Kraus:

Tai & Pereir

4 4 41, 253

41, 253 41, 25327.63 14.51 dB

(38.64)

Di

15 72,81524.38 13.87 dB

2(3

rectivi

10.1158 10.

a:

Using the computer program t ,

05

y

8.64)d d

A r r d d

d d

D

D

D

D

dB

8



Directional Patterns



0 20 2

Elsewhere

1,2,3 10,15, 20

cos ,

0

noB

U

n



Radiation Intensity Pattern

4

(

0 90

, ) co

3

s

0 60

o

o

U


Exact & Approximate DirectivitiesTable 2.1

5.5n




Kraus’ Error = 0n = 5.497 5.5

HPBW = 56.35º

|Kraus’ Error|=|T & P’ Error|=6.24% n = 11.28

HPBW = 39.77º



OmindirectionalPatterns

9



Omnidirectional Pattern With Minor Lobes Normalized Field

Pattern (linear scale)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

x y

z

)0

sin0

(2

nU


Omnidirectional Pattern Without Minor Lobes


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

xy

z

)0

sin0

(2

nU




Omnidirectional Patterns

sin ( )0

0 2nU

Directivity:

0 2

0

101

HPBW(degrees) 0.0027[HPBW(degrees)]

1172.4 191 0.818

HPBW(degrees)

D

D

McDonald

Pozar


March 20, 2019

Gain


March 20, 2019

DirectivityRealized

Gain

inP

Gain

radP

+inP

+inP

inPCopyright©2016 by Constantine A. Balanis All rights reserved


Radiation efficiency

Conduction efficiency

Dielectric efficiency

cd c d

c

d

e e e

e

e

(2-49a)00 cdG e D

10



Antenna Radiation Efficiency

cde

Horn Antenna And Its Circuit Equivalent

RL

Horn Equivalent




Power Radiated by Antenna ( )

Power Delivered

Radiati

to Ant

on Effi

enna

c ency

( )

icd

cd

r

r

d

L

cr

r

L

P

e

e

Re

R R

P P




10

1

0

0

10

0

10log

10log ( )

(dB)

(

+10l )

d )

(

B

og

cd

cd

o

o

e

e

DG

G

D

0 0

cd

cd

G

D

e

eG

D



Antenna Reference Terminals



RealizedGain

11



DirectivityRealized

Gain

inP

Gain

radP

+inP

+inP

inPCopyright©2016 by Constantine A. Balanis All rights reserved


2

2

(1 | | )

antenna total efficiency

(1 | | ) Reflection efficie

Radiation efficiency

Conduction

ncy

( , ) ( , )

( ,

( , )

efficiency

Dielectric effic

( ), ) cd

cd c d

r

d

ore r cd

in

o

e

r in

r e

e

e eD

e

G

G

e

e

D

e

e

D

e

e

iency

Realized Gain Gre

Today antenna technology is

ScienceNotArt

Very bright future and many challenges ahead. We just need exercise creativity,

imagination and science for its advancement.


March 20 2019

Antennas and Fundamental Parameters February 20, 2019...Definition of Antenna The guiding device or...

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