connor antennas lecture

8/19/2019 Connor Antennas Lecture

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Fields and Waves I

Lecture 26Intro to Antennas & Propagation

K. A. ConnorElectrical, Computer, and !stems Engineering "epartment

#ensselaer Pol!tec$nic Institute, %ro!, '


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March 22, 20 Fields and Waves I 2

%$ese lides Were Prepared (! Pro). Kennet$ A. Connor *sing+riginal aterials Written ostl! (! t$e Follo-ing

Kennet$ A. Connor / ECE "epartment, #ensselaerPol!tec$nic Institute, %ro!, '

0. "arr!l ic$ael / 1E 1lo(al #esearc$ Center,isa!una, '

%$omas P. Cro-le! / ational Institute o) tandards and %ec$nolog!, 3oulder, C+

$eppard 0. alon / ECE "epartment, #ensselaerPol!tec$nic Institute, %ro!, '

Lale Ergene / I%* In)ormatics Institute, Istan(ul, %ure!

0e4re! 3raunstein / C$ung5Ang *niversit!, eoul, Korea

aterials )rom ot$er sources are re)erenced -$ere t$e! areused. %$ose listed as *la(! are gures )rom *la(!7ste8t(oo.


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E8amples o) Antennas


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Antennas


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moteiv %mote !Inverted FAntenna


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moteiv %mote !


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moteiv %mote !


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moteiv %mote !


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moteiv %mote !


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%ransmission Lines &Antennas

#evie- %ransmission Lines

#evie- 3oundar! Conditions

#evie- 9oltage, Current, Electric andagnetic Fields

Etc.


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%E Waves on %ransmissionLines

Connecting *ni)orm Plane Waves -it$ 9oltages andCurrents on %ransmission Lines

E z E e E e x j z j z( ) = ++

−−

+β β

H z E e E e y

j z j z

( ) = −+−

−

+β β

η


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%E Waves

%$ese elds can e8ist in t$e region (et-een t$e conductingplates i) t$e (oundar! conditions on t$e plates arereasona(l! satised. ince t$e electric eld $as onl! an x component, it is totall! normal to t$e conducting(oundaries. %$is can occur i) t$ere is a sur)ace c$arge ont$e (oundar!, ρ ε ε ε β β s x

j z j z E z E e E e= = ++−

−+( )

%$e magnetic eld is totall! tangent to t$e conducting(oundar!, -$ic$ can occur i) t$ere is a sur)ace current

densit! given (!

J H z E e E e

s y

j z j z

= = −+

−−

+

( )β β

η


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%E Waves

%$en, assuming t$at t$e lo-er plate is grounded, t$e voltageon t$e upper plate -ill (e

( )v z E z d x s E e s E e V e V e

x

s j z j z j z j z= = + = +

∫ +

−

−

+

+

−

−

+( )0

β β β β

-$ere -e $ave integrated t$e electric eld along t$evertical :red; pat$ s$o-n.

s

w


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%E Waves

%o connect t$e magnetic eld -it$ t$e current, -e mustintegrate along a closed pat$ t$at encloses one o) t$e t-oconductors. %$e (ottom pat$ s$o-n includes t$e $ori


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%E Waves

For a parallel plate -aveguide :stripline;, t$e inductance andcapacitance per unit lengt$ and intrinsic impedance are

l

s

w=

µ

c

w

s=

ε

Z l

c

s

ww s

s

w

s

wo = = = =

µ

ε

µ

ε η


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%E Waves

so t$e current e8pression is

i z V e V e

Z

j z j z

o

( ) = −+

−−

+β β

We could $ave determined t$is current )rom t$e sur)acecurrent densit! so -e s$ould c$ec to (e sure t$at t$e t-oresults agree. %$e total current at an! z s$ould (e given (!

i z J w E e E e w V e V eZ

s

j z j z j z j z

o

( ) = = − = −+−

−+

+−

−+β β β β

η

as (e)ore.


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%E Waves

Finall!, -e can c$ec to see i) t$e c$arge per unit lengt$ :asdetermined )rom t$e (oundar! condition; gives us t$e usualcapacitance per unit lengt$.

( ) ( )q w w E e w E e w s

V e V e c v z s j z j z j z j z

= = + = + =+−

−+

+−

−+ ρ ε ε

ε β β β β

as e8pected.

%$e same anal!sis can (e done )or coa8ial ca(les and t-o5-ire lines. %$e general results are t$e same.


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tanding Waves9oltage tanding Wave -it$ $ort Circuit Load

ConstructiveInter)erence

"estructiveInter)erence


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tanding Waves9oltage tanding Wave -it$ +pen Circuit Load


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0ava Applet o) Waves

$ttp==---.(essernet.com=Ere>ecto=tutorialFrameset.$tm

tanding Wave

http://www.bessernet.com/Ereflecto/tutorialFrameset.htmhttp://www.bessernet.com/Ereflecto/tutorialFrameset.htm


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imple Antennas

Currents on Wire Antennas

1eneral %!pes o) Antennas

%$e ?ert


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imple Wire AntennaCurrents

From C%A 0o$n EngineeringElectromagnetic Fields & Waves


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%!pes o) Antennas


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?ert


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?ert


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ote t$at t$e-aves(ecomeplanar atlarge

distances


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?ert


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$ort "ipole


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Aperture Antennas


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Antenna Parameters

Calculate t$e Electric and agnetic Fields )rom

t$e Antenna Currents / usuall! re@uires t$euse o) potentials

Far Fields are Products o) terms lie t$e)ollo-ing / :depends on current and inversel!

on position;, sp$erical -ave, eld pattern "etermine t$e Po!nting 9ector / Po-er "ensit!

is product o) E and ? / average goes inversel!-it$ position s@uared and -it$

1ain is t$e ratio o) po-er densit! to isotropicvalue

#adiation #esistance is t-ice t$e average totalpo-er divided (! t$e current s@uared

( ) F θ

( ) F 2 θ


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Antenna Anal!sis

?ert


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Antenna Anal!sis


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Antenna Anal!sis


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Antenna Anal!sis

Keep +nl! %$e Largest %erms in t$e Far

Field


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Antenna Anal!sis( ) F 2 θ


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Antenna Anal!sis


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ote t$at t$e-aves(ecomeplanar atlarge

distances


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?ert


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?al) Wave "ipole

( ) F 2 θ


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#adiation Patterns

$ttp==---.$!perlintec$.com=-e(=$gB!.p$p

http://www.hyperlinktech.com/web/hg914y.phphttp://www.hyperlinktech.com/web/hg914y.php


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Antenna

Patterns

' i A


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'agi Antenna

D.1?<

B El t ' i


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B Element 'agi

$ttp==---.astron-ireless.com=li(rar!.$tm

http://www.astronwireless.com/library.htmlhttp://www.astronwireless.com/library.html


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P t $ A t


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Patc$ Antenna

P t $ A t


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Patc$ Antenna

P t $ A t


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Patc$ Antenna

P t $ A t


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Patc$ Antenna


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$ttp==etd.li(.)su.edu=t$eses=availa(le=etd5B25BG6D6=unrestricted=C$apter.pd)

http://etd.lib.fsu.edu/theses/available/etd-04102004-143656/unrestricted/Chapter4.pdfhttp://etd.lib.fsu.edu/theses/available/etd-04102004-143656/unrestricted/Chapter4.pdfhttp://etd.lib.fsu.edu/theses/available/etd-04102004-143656/unrestricted/Chapter4.pdfhttp://etd.lib.fsu.edu/theses/available/etd-04102004-143656/unrestricted/Chapter4.pdf


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$ttp==Hournals.tu(ita.gov.tr=eletri=issues=el5D5BG5B=el5BG5B555

Antenna Polari


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Antenna Polari


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?ori


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In t$e earl! da!s o) F radio in t$e 5B ?< spectrum,t$e radio stations (roadcasted $ori


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Circular polari


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Antenna Polari


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Antennas

%$e simplest antenna is t$e ?ert


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Antennas

%$e electric eldaround t$e?ert


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Antennas

Po-er is radiated$ori


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Antennas ?al) Wave "ipole vs uarter Waveonopole

Antennas / ?al) Wave "ipole vs uarter Wave


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Antennas ?al) Wave "ipole vs uarter Waveonopole

Antennas / ?al) Wave "ipole vs uarter Wave


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p onopole

3ertoni lides


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3ertoni lides

E8tensive lides on Propagation, Etc )orWireless$ttp==ee-e(B.pol!.edu=)acult!=(ertoni=e

l6D.$tml
http://eeweb1.poly.edu/faculty/bertoni/el675.htmlhttp://eeweb1.poly.edu/faculty/bertoni/el675.htmlhttp://eeweb1.poly.edu/faculty/bertoni/el675.htmlhttp://eeweb1.poly.edu/faculty/bertoni/el675.html

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