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U N I V E R S I T I T U N H U S S E IN O N N M A L A Y S I A

F I N A L E X A M I N A T I O NS E M E S T E R I

SESSION 2009/2010

S U B J EC T N A M E AP P LIED ELEC TR OM AGNETIC SS UB J EC T C ODEC O U R S E

BEE 32233 BEE

DATE OF EXAM NOVEM B ER 2 0 0 9D U R A T I O NI N S T R U C T I O N

3 HOUR SANS WER ALL QUES TIONS IN P AR T A.ANS WER THR EE (3 ) QUES TIONSONLY IN P AR T B .

T H I S P A P E R C O N S I S T S O F E I G H T P A G E S

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B E E 3 2 2 3

Q5 (a) Iden tify TH RE E (3) criteria for the system to be considere d ase lec t romagne t ica l ly compat ib le .

(3 marks)(b ) D is t ingu ish the in te r fe rence be tw een mobi le phone and d ig i tal com pute r

s igna l t ransmiss ion s i tua t ions to a source , coup l ing pa th and recep to r . Ex p la inbriefly the situation.(5 marks)

J

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B E E 3 2 2 3

P A R T BQ6 (a) A stub length of 0.12A. is used to mat ch a 60 Q lossless l ine to a load. If the

shorted-stub is located at 0 .3X from the load, calculate:( i ) the load impedance , Z l(ii) the length of an alternative stub and its location fro m the load.(i i i) the standing wave ratio betwee n the stub and the load, S

(15 marks)(b) A 50 Q lossless transm ission line uses an insulating material w ith

e r = 2.25. W hen term inated in an open circuit , how long sho uld the l ine be fori t s inpu t impedance , Zm to be equivalent to a 10 pF capacitor at 50 MHz?(5 marks)

Q 7 (a ) With the a id o f d iagram, exp la in w hy s ing le mo de p ropaga t ion in thew avegu ide i s h igh ly des i rab le in mic ro w ave sys tem.(4 marks)

(b ) D is t ingu ish be tw een TE mod e and TM mode .(4 marks)

(c ) In a i r f i l led rec tangu la r w avegu ide , the cu to f f f requen cy o f a TE l0 m o d e i s5 G H z, w hereas tha t TE m mode i s 7 .5 G H z.( i ) D e te rm ine the d imen s ions o f the w aveg u ide . (4 mark s)( i i ) Ca lcu la te the num ber o f mod es tha t the w avegu ide suppor ts i f theoperating used is 7.8 GHz .

( 2 m a r k s )(ii i) Sugg est TW O (2) steps that can be taken in such a wa y that thew avegu ide suppor t s ing le mode on ly .

( 4 m a r k s )( iv ) O ver w ha t f requency range w i l l the gu ide suppor t the p ropag a t ion o f as ing le dominan t mode?

( 2 m a r k s )

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B E E 3 2 2 3

Describe the major lobe, side lobes, back lobes and nulls for an antenna.(4 marks)

D es ign a f ive -e lement Y ag i-U da a r ray f rom the bas ic d ipo le fo r a f requency o f200 MHz. Il lustrate your design by indicating the length and spacing ford r iven and paras i t ic e lements .(6 marks)

A probe m easured 2 pV /m of f ie ld s t reng th 100 km aw ay f rom a pa rabo l icantenna with directive gain of 1000 and efficiency of 0.85. Calculate(i) The pow er gain( i i ) The EIRP of the pa rabo l ic an tenna .(i i i) The radiated pow er, P rac i and input power, P in(iv) The distance of the prob e if an isotropic antenn a is used for the sam e

amount of f ield strength.(10 marks)

Q 9 A commun ica t ion l ink be tw een the headquar te rs in c i ty A to a subs id ia ry ou t le t inc i ty B w hich i s 60 k i lometres aw ay i s go ing to be se t up . The communica t ion l inkw i l l u t i l ize the new ly acqu i red 4 G H z spe c t rum fo r t ransmiss ion a nd a 20 dB Wtransmit te r and 15 dBi ga in an tennas fo r bo th t ransmi t te r and rece iver s ta t ion . D ur ingthe site survey, a knife edge hill with height of 40 metres from sea level is foundloca ted a t the midd le o f the p roposed com mun ica t ion pa th .(a ) F ind the he igh t o f the p ropo sed t ransmi t te r and rece iver tow e r so tha t thed i f f rac t i on loss can be neg l ig ib le . A ssume the same t ransmi t te r and rece iverhe igh t .

(7 marks)(b) If both the transm itting and rece iving tower is only 15 me tres in height fromsea level, calculate the loss due to the obstacle.

(5 marks)(c ) Ca lcu la te the f ree space loss in be tw e en the comm unica t ion l ink .

(2 marks)(d ) F ind the e f fec t iv e i so t rop ic rad ia ted pow er (E IRP) o f the t ransmi t te r in dBWand Wat t .

5

Q 8 (a )

(b )

(c)

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B E E 3 2 2 3

(3 marks)(e) Find the received pow er, P R , a t the rece iver in dBW and Wat t . A ssume the reare no other losses in the system.

(3 marks)

Q1 0 (a) One of the reasons to consi der electrom agnetic com patibili ty is to achie ve th edes i red func t iona l pe r fo rmance o f a d ig i ta l c i rcu i t ry sys tem. Recommend thecon t ro l techn iques o f e lec t romagne t ic in te r fe rence w hi le des ign ing the sys tem .D ra w the appropr ia te f igures to exp la in the techn iques .( 1 0 m a r k s )

(b ) D raw the b lock d iagrams to i l lus tra te FO U R (4) bas ic o f EM Csubprob lems .( 4 m a r k s )

(c ) P ropose rad ia ted emiss ion measurement se tup us ing O N E (1 ) o f the fo l low in gmeasurement fac i l i t ie s be low :( i ) O pen A rea Tes t S i te( i i ) G TE M Cel l( i i i ) A necho ic Cham ber

(6 marks)

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BEE 3223

F I N A L E X A M I N A T I O NSEMESTER/SESSIONSUBJECT NAME : SEMESTER I SESSION 2009/2010: APPLIED ELECTROMAGNETICS COURSE: 3 BEECODE : BEE 3223

F O R M U L A SI M P O R T A N T E Q U A T I O N S F O R T M A N D T E M O D E S

T M M o d e s T E M o d e sExs = - jP T mrti ^ r rEys =

(mux ) . ( mryE 0 cos - sm -V a J [b ). f mmO f nrcyE n sm cosI a J I b)

. , mitx'i . (nrcy^Ezs = E n sin sin1 a J { b

-yz

-yz

-yz

Hxs = jcos n7t . (nmxE 0 sinV a ; cosrnty -yz

jcos f nrnH ys = - i h 2 V aHzs = 0

E 0 cos rmtx sm niiy - y z

n = ri\ t- r c \ 2rcv f y

Exs = ^ ^ lH o c o s/ \mux sin nityv~b~y - y z

Ezs = 0

rT j(3 f m uV r . (muxH x s = M ^ J o S i n u C O Snicy -yz

Hys = jP nre . |H 0 cos mjtx sm rnzy yzb '

Hzs = H 0 cosTV

f mux rcos r n . l - y zb

f ^c

a c for TEjnjQ modes where n ^ 0:

i 2 R sa c Ite => 1 ' f -

a c f o r T E i o m d e :

l cfj cf

b f b 2 22 - - m z + n zI a U ; f i ^1b~ 2 2

a~a c for TM modes:

a c lTEio = 2R sb T ] ' l l 1 - r t c i

2b T ] ' l l Lt J

/ 1 b V 2 1 +2 a fV ya c Itm=- 2 R s ( b / a ) 3 m 2 + n 2r f r i 2 ( b / a ) 2 m 2 + n 2

bT] ']l 1 - c2 ( b / a ) 2 m 2 + n 2

bT] ']l L * J

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The Complete Smith ChartBlack Magic Design