Technical University of Gdansk

Department of Radio Communications

Radio Communication Antennas

by

prof. Ryszard J. Katulski

Field of Study: Electronics and Telecommunications

Level: MSc.

2

List of the Lecture Topics:

1. Antenna aspects in radio communication link

2. Principles of antenna choice in fixed and mobile link

3. Omnidirectional antennas

4. Sectorized antennas

5. Narrow beam antennas

6. Antenna technique for land mobile communications

7. Microstrip antenna technology

8. Properties of the microstrip antennas

9. Antenna technique for fixed satellite communications

10. Antenna equipment for mobile satellite terminal

11. Base theory of diversity receiving

12. Diversity antenna technique

13. Antenna technique for maritime communications

14. Smart antenna

15. Miniaturization of antenna equipment

3

1. Antenna aspects in radio communication link – introduction

- Structure of the radio link (transmitter/receiver with wireless part)

- Fixed and mobile link antenna properties

- Omnidirectional and directional properties

- Network structure aspects

- Radio access cellular structure

- Fixed or mobile networks

- Base station and terminal equipment antennas properties

- Sectorized antenna properties

- Adaptive antenna in mobile link (smart conception)

4

Structure of the radio link (transmitter and receiver with wireless part)

one-directional case

Tr

radiowave propagation medium

Transmitter Antenna

Gt [dB], gt

Receiver Antenna Re

Gr [dB], gr

wireless part of the radio link

5

Structure of the radio link (transmitter and receiver with wireless part)

two-directional case

Tr/Re

radiowave propagation medium

Tr/Re Antenna

G [dB], g

Tr/Re Antenna

Tr/Rc

G [dB], g

wireless part of the radio link

6

EMC aspect of antenna properties

- antenna interface:

- desired (main beam),

- undesired pattern (side and back pattern),

- omnidirectional (isotropic),

- sectorized,

- narrow-beam,

- adaptive pattern (smart antenna):

- dynamically adaptation of a Spatial Channel,

- reduction of an Interfernce Field,

- increase of a Network Capacity

Transmitter or Receiver

Radiowave Propagation

Medium

wire part

Antenna Interface

wireless part

7

Fixed and mobile link antenna properties

- Omnidirectional or directional properties:

- Fixed: directional properties

- Mobile: omnidirectional properties (simple case)

TR/RE

x xTR/RE

x

1v

x

2v

TR/RETR/RE

2º Mobile:

1º Fixed:

8

Network structure aspect

- multi-station point-to-point network structure:

- multi-station point-to-area cell structure – concept of a base station with terminals

(multi-users wireless access to telecommunication services):

x

TR/RE

x

x

x

TR/RE

TR/RE

TR/RE

TR/RETERMINAL

x

x

x

x

TR/RETERMINAL

xTR/RE

TERMINAL

TR/RETERMINAL

TR/REBASE STATION

9

point-to-point network structure

- Radio-station antenna properties in fixed network

– directional:

- Radio-station antenna properties in mobile network

- omnidirectional:

x

TR/RE

x

x

x

TR/RE

TR/RE

TR/RE

4v

x

2v

TR/RE

TR/REx

3v

TR/RE

x

x

1v

TR/RE

10

Cell structure with base station - fixed network case:

- Base radio-station antenna properties

– omni or directional (sector or narrow beamwidth)

- Terminal radio-station antenna properties

– directional (narrow beamwidth)

xx

TR/RETERMINAL

x

x

x

xTR/RE

TERMINAL

TR/RETERMINAL

TR/RETERMINAL

TR/RETERMINAL

TR/REBASE STATION

x

x

x

BASE STATION

x

11

Cell structure with base station - mobile network case:

- Base radio-station antenna properties

– omnidirectional or sectorized or …?

- Terminal radio-station antenna properties

– omnidirectional (rather) or hemispherical

x

xv

x

v

x

v

x

v

1º) Omni-base

x

2º) Sectorized-base

xv

xv

x v

xv

12

Adaptive antenna in mobile link (smart conception)

- interference problem (desired and undesired signals):

if for base station omnidirectional pattern

then for base station directional pattern

- antenna array with weight elements and adaptive processor should be applied

- basic conception on example of linear antenna array:

and

pAssp udbeamomni

2

'sec pp beamtor

2

2

K

mmm twtxty

1

min yre

W1

x1

W2

x2

x1·W1

S

x2·W2

Wk

xk

xk·Wk

1 2 k

Adaptive processor

y(t) r

e

13

Adaptive antenna directivity properties analysis

- 1-D case (equation and scheme):

Km

mmmmmm

K

mmmmm

AAAA

practicein

wtWtwandAx

where

wtjtWAtF

......

:

argexp ,exp

:

argexp,

21

1

W1

x1

W2

x2

x1·W1

S

x2·W2

Wk

xk

xk·Wk

1 2 k

Adaptive processor

y(t) r

e

14

Adaptive antenna directivity properties analysis

- 2-D case (equation and scheme):

NKnm

nmnmnmnmnmnm

N

n

K

mnmnmnmnm

AAAA

practicein

wtWtwandAx

where

wtjtWAtF

......

:

argexp ,,exp,

:

arg,exp,,

1211

1 1

1 K

2

N

2

15

Adaptive antenna system

rxxxw

where

jxjwjrje

optimum

T

,,

:1

x

S

Processor Unit

{W}

{X}

y

e

r+

-

16

Adaptive criterions

- SNIR (maximum of Signal-to-Noise-Interference Ratio):

- MSE (minimum of Mean Square Error):

- correlation method

Iundesired

desired

PP

Pmin

trtyERandtxtxERwhereRRW yrxxyrxx**1

N

ii

i

en

ewhere

eeEyre

1

22

1

min,min

17

Adaptive procedure – two steps (scheme):

- DOA (Direction of Arrival)

- beamforming

(scheme)

18

Simple illustration of the DOA (scheme)

19

DOA algorithms (equations)

20

Beamforming procedure

- amplitude or phase steering

- phase array

(scheme + equations)

21

2. Principles of antenna choice in fixed and mobile link

- firstly, the antenna directivity properties should be taken into

account due to the shape and range of the radio system operation area,

- secondly, the antenna gain should be taken into account due to

the energetic bilans od the radio link,

- for fixed link, the antenna equipment with possible small value

of the beamwidth is best solution,

- for mobile link, its depends on the kind of a radio-station:

- for base station the sectorized antenna equipment is prefered,

- for user terminal the short microstrip antenna is prefered

22

3. Omnidirectional antennas

- omnidirectional is not same as an isotropic property

(isotropic antenna is omnidirectional in each plane – theoretical model)

- omnidirectional antenna is practical case with non-directivity properties

in one plane only

- typical omnidirectional are bellow antennas:

- half-wavelenght dipole in H-plane

- linear antenna (wip antenna) in H-plane

23

4. Sectorized antenna properties

Antenna array with beamwidth:

- in horizontal plane (depends on users traffic)

- in vertical plane

- with few degrees tillt (non everyone)

(typical pattern with catalog)

00 15 7 tofrom

000 60 90 ,120 or

24

Sectorized antenna structure

- half-wavelenght dipole or rectangular microstrip radiator array

- vertical polarization (in a base version)

- feeder line

- coupling problem

25

5. Narrow beam antennas

- narrow beam in each plane (in E-plane and H-plane in practical)

- reflector’s antennas (parabolic form)

- by use rectangular antenna array (high gain)

- in mobile link a main beam position should be steering

26

6. Antenna technique for land mobile communications

- base radio-station antenna

- omnidirectional in wip form (one cell network with small

traffic)

- sectorized in array form (multi-cell network with big traffic)

- antennas for space and polarization diversity

- terminal antenna

- omnidirectional in wip form

- hemispherical in short microstrip radiator form

27

7. Microstrip antenna technology

- view of a microstrip radiator:

- main properties of one radiating element:

- integrated and simple construction

- easy technological process

- high energetic effectivness

- small directivity properties

- in wireless systems the radiating element array should be

applied

28

Microstrip antenna technology – geometry of a microstrip line

ZCT Y G jBS S S

c)

rH

b)

x

z

apertura

l

W m

d)

W m

a)

x

y

29

Microstrip antenna technology – slot admitance

- slot conductance

- slot susceptance

- slot admitance

where: and

moreover: and

SSS jBGY ˆ

mSS WgG

mSS WbB

mSSmSS WjbgWyY ˆˆ

241

2Hk

Zg

CTdS

CTd

S Z

Hkb

lg2135,3

re

d

0mre

CT W

HZZ

0

30

Microstrip antenna technology – slot radiation conductance

- slot admitance

- in practice

- in result

conclusion:

to obtain antenna phenomena

with good value of the radiation conductance,

the width of a microstrip line should be greater

radG

surfradS GGG

surfrad GG

mCTd

mSradS WZ

WgGG

31

Microstrip antenna technology – field distribution in a slot

H

x

z

l

Er

A B

CD

E z

Ea

32

Microstrip antenna technology

– geometry of a rectangular microstrip radiator

(usefull practical form of the antenna)

L ef+l

E nE r

E tE nE r

E t

F W

L

+ = E t E t+

a)y

x

b)

H

ll

c)

d)

L ef

LL

33

Design procedure of the microstrip rectangular radiator:

- choice of a dielectric layer

- radiator width

- radiator lenght

where:

and

WandL

LL d 2

dW

813,0258,0

262,03,0

412,0

L

WL

W

HL

re

re

2

1

1212

1

2

1

W

Hrrre

Handr

34

Microstrip antenna technology – feeding techniques

b)

c)

a) Linia zasilająca

Promiennik

Linia zasilająca

35

8. Electrical properties of the microstrip antennas

– main analysis techniques

- modelling techniques of the microstrip rectangular radiator

- transmission or cavity equivalence

(schemes of the microstrip lines and cavity without descriptions)

36

Transmission model of the microstrip rectangular radiator

Y sY s

Z we

L ef

b)

L+ l

F W

L

Z CP

a)

c)

y

x

l l

W ef

LL

37

Transmission model of the microstrip rectangular radiator

- Electrical (directivity) properties of the antenna

Radiation pattern:

plane z-in x sin2

cos

2

sin2

sinsin

0

0

0

effE

Lk

Hk

Hk

F

plane z-yin cos

2

sin

2

sinsin

0

0

eff

eff

H Wk

Wk

Fz

y

x

L

W

r

P (,,r)

38

Transmission model of the microstrip rectangular radiator

- Electrical (admitance) properties of the antenna

Resonant input admitance:

deffd

eff

deffdd

eff

deffd

eff

rad

WW

WW

WW

G

2for 120

235,0for 60

1

120

35,0for 90

2

2

2

2

2

39

Transmission model of the microstrip rectangular radiator

- Electrical (impedance) properties of the antenna

Input impedance vs. frequency:

where:

Resonant frequency:

where:

1

1ˆ

resCP

resin f

ftgjY

ZfZ

W

HZ

YZ

reCPCP

01

effres L

cf

1

2

LLLandsmc eff 2 /103 8

40

Cavity model of the microstrip rectangular radiator – general description

z

y

x

H

a)

L ef

W ef

Fy 0

x 0

C G

C 10G 10L 10

C mnL mn G mn

TM mn

TM 10

C 10G 10L 10

TM 10

L T

b) c)

y

x

W ef

L ef

l

l

lA 2

A 4

A 3

A 1l

d)

0 0

,),(m n

mnmnz yxAyxE

H

VA mn

mn

effeffmn W

ym

L

xm coscos

00

r

mnmn

k

2

122

effeffmn W

n

L

mk

41

Cavity model of the microstrip rectangular radiator

- resonant impedance properties for base mode:

where:

LTresin jXRfZ 10

cudirad GGGGR

11

1010

cudirad GGG

% 100

1

in

rad

R

G

42

Transmission and cavity model of the radiator - comparison

- Radiation pattern in E-plane (x-z plane)

-16

-12

200-20

6040 80

-8

f = 1,6 GHzr = 2,1h = 1,5 mm

-4

0

modeltransmisyjny

pomiar

modelwnękowy

F( )[dB]

z

y

x

L

W

r

P (,,r)

43

Transmission and cavity model of the radiator - comparison

- Radiation pattern in H-plane (y-z plane)

-16

-12

200-20

6040 80

-8

f = 1,6 GHzr = 2,1h = 1,5 mm

-4

0

modeltransmisyjny

pomiar

modelwnękowy

F()[dB]

z

y

x

L

W

r

P (,,r)

44

Polarization techniques of the microstrip antenna

- by special radiator feeding

- quasi-kwadrature shape of the radiator:

x

y

L

W

H r

05,1029,1 W

L

45

Polarization techniques of the microstrip antenna

- by use of the four radiator array

(schemes and desription)

46

Microstrip radiator – stacked technology

- to increase frequency band due to radio systems application requirements

- especially for modern wide band radio systems

x

y

L

W

H

H

r

r

47

Hemispherical antenna in short microstrip radiator form

(figure)

48

Microstrip rectangular array

(scheme)

49

9. Antenna technique for fixed satellite communications

- for Earth Station application

- high gain with narrow beam of directional properties

- parabolic reflector antennas

- radiation source constructions (polarization aspect)

- linear polarization can be applied but circular is better

- horn antennas (open waveguide) with linear or circular

polarization

- half wavelenght dipole with linear polarization

- crossed dipoles with circular polarization

- for Space Station application

- high gain with narrow beam by use dipole or slot antenna arrra

- or multi-beam antenna array

50

parabolic reflector antenna construction

- with clasical reflector

51

parabolic reflector antenna construction

- with offset reflector

52

parabolic reflector antenna construction

- with dual reflector (Cassegraine Antenna)

53

Horn antennas (open waveguide)

- a polarization of e-m field in waveguide decides about type of the horn

antenna polarization

54

Crossed dipoles with circular polarization

- analytical description of the dipoles:

- to obtain circular polarization:

- to obtain required value of the input impedance:

d y

lx d x

ly

Y1Y2

a) b)

2222111121 ˆ ˆ jBGeYYandjBGeYY jj

2 2121

andYY

)50( 21 GG21

1

GGZ in

55

Antennas for Space Station application

- one- or multi-beam antenna array

56

10. Antenna equipment for mobile satellite terminal

- satellite antenna techniques for vehicles (on land and sea) with

optional directivity properties depend on kind of

telecommunications services (transmission rate in kbits/s):

- rectangular microstrip radiator and array

- short backfire and helical antenna constructions

- circular polarization should be applied

- crossed dipoles

- antenna equipment for personal satellite terminal

- microstrip radiator with hemispherical pattern

57

Satellite antenna equipment for vehicles

- relative wide beam should be applied due to permanent change

of antenna position (orientation to satellite)

- optional directivity properties:

- best option with high gain equals more than 20 dB (full

service)

- medium option with gain from 10 to 20 dB (limited service)

- simple option with gain equals few dB (small transmission

rate)

- kind of service:

- full (high transmission rate with the few Mb/s)

- medium (transmission rate with the few kb/s)

- simple (transmission rate is smaller than kb/s)

58

Idea of the backfire antenna construction

- big and small reflectors with radiation source

x

z

y

D

M

59

Schemes of the short backfire antenna practical construction

S

S

B

F

B

R

Z

S

a)

b)

,......2,1 ,35,0max nnDB

,......2,1 ,75,0min nnDB

5,0sD

25,021 FF ll

1rl

60

Short backfire antenna properties – radiation patterns

- one source antenna

- four array

0

-10

dB

-20

-30

0° 30° 60° 120°90° 150° 180°

Modelowanie

Pomiar

F

0

-10

dB

-20

-30

0° 30° 60° 120°90° 150° 180°

Modelowanie

Pomiar

F

61

Helical antenna constructions

- axis radiation in satellite link application

with circular polarization

- orthogonal to axis radiation -

with linear polarization

(wip antenna eqivalence) in land mobile terminal

- scannig axis in radio-monitoring

- for axis radiation:

and

D

l

S

DCwhere

CS

2,17,0 3,015,0 1412 00

mm l 3

4

4

3

)( Dl

62

Helical antenna analysis

- radiation properties (pattern for axis radiation):

- radiation properties (polarization)

from axis to ortogonal radiation :

- impednace properties for axis polarization:

cos

2sin

2sin

0 SkwhereN

N

F

)0( 0 )90( 0 cosp

RkZ in 140

y

z

x

P (,,r)

r

R

63

Reflectors for helical antenna

with

with

D s

Ekran

00 1401102 8,0 mSD

mD 4,0

64

Helical antenna properties

65

11. Base theory of diversity receiving

66

12. Diversity antenna technique

- antenna for space diversity

67

antennas for polarization diversity

- with two orthogonal linear polarizations

- +/- 45 degrees

- 0/180 degrees (horizontal/vertical polarizations)

68

13. Antenna technique for maritime communications

- wip and mast antenna

a) current distribution

b) radiation pattern

c) omidirectional in horizontal plane

a

b

69

analysis method of the wip and mast antenna – thin-wire model

where:

method of moments procedure is applies to determination of the current

distribution as parameter to calculate of radiation pattern with input impedance

and coupling problem analysis of a ship antenna array

l

z

d

x

y

e

l

zEjdzzzGzIkz

4, '''22

2

'

''

,

,exp,

zzR

zzjkRzzG

70

Antenna technique for maritime communications

- link antennaa) b)

lVlV

hV

lV

hV

h h

lHlH

lZ

lV

71

Satellite antenna equipment for ship application

- changes of the ship position

- relative wide beam should be applied due to permanent change of antenna

position (orientation to satellite)

- optional directivity properties:

- best option (A standard) with high gain equals more than 20 dB (full

telecommunication service)

- medium option (B standard) with gain from 10 to 20 dB (limited service)

- simple option (C standard) with gain equals few dB (small transmission rate)

- kind of service:

- full (high transmission rate with the few Mb/s)

- medium (transmission rate with the few kb/s)

- simple (transmission rate is smaller than kb/s)

72

Antenna technique for underwater communications

- link antenna a)

b)

c)

73

14. Smart antenna

74

15. Miniaturization of antenna equipment