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TRNG I HC BCH KHOA H NIVIN IN T- VIN THNG

s2. Tng strang: 1

THI MN: Anten truyn sng. TVT K55Ngy thi: 28.12.2012. Thi gian: 90 pht(Khng c sdng ti liu, np thi cng bi lm)

Duyt Trng nhm Mn hc Trng bmn

I. PHN TRC NGHIM (3 im)1. Sng in ttruyn trong khng kh kh ca tng

i lu ( c coi nh mi trng in mi ltng) l:A. Sng in tngang TEMB. Sng in ngang TEC. Sng tngang TMD. C3 dng sng trn

2. Sng ngnph hp vi phng thcA. Truyn sng trong tm nhn thngB. Truyn sng phn xtng in lyC. Truyn sng bmtD. C3 phng n trn

3. Trong phng thc truyn sng bmt, antenc tA. Song song vi mt tB. Nm nghing vi mt tC. Vung gc vi mt tD. Khng quan trng, t cch no cng c

4. Dn anten bc xthng c N phn t, khongcch gia cc phn tl d. Hsnh hngca anten phthuc vo:A. Sphn tNB. Khong cch gia cc phn tdC. di hthng L=NdD. C3 phng n trn

5. Trong thng tin vtinh ngi ta sdng:A. Anten TuanikeB. Anten loaC. Anten parabolD. Anten Yagi

6. Thng tin Viba sdng di sng:A. Di v cc diB. Sng trungC. Sng ngnD. Sng cc ngn

II. TLUN(7 im)Cu 1:Trnh by nhng nh hng chnh ca tng in ly n truyn sng v tuyn v bin phpkhc phc (nu c)Cu 2:2.1Tuyn thng tin viba cly 40 km, anten pht cao 60m, my pht lm vic tn s2GHz. Hi

anten thu phi c chiu cao ti thiu l bao nhiukhi vtr gia ng truyn c mt tanh (vt cn) cao 40m, trong hai trng hp:a. Coi mt t l phng

b. Mt t cong (bn kinhd tri t l 6378 km).2.2Vi tuyn thng tin viba trn ,trong trng hp coi mt t l phng, nu cng sut my pht

l 10W, anten pht c hsnh hng D=100. Tnh trng Ebnhn c ti im thu khibqua cc tn hao trn ng truyn

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TRNG I HC BCH KHOA H NI

VIN IN T- VIN THNGs1. Tng strang: 1

THI MN: Anten truyn sng. TVT K55Ngy thi: 28.12.2012. Thi gian: 90 pht(Khng c sdng ti liu, np thi cng bi lm)

Duyt Trng nhm Mn hc Trng bmn

I. PHN TRC NGHIM (3 im)1. Di sng no di y ph hp vi truyn sng

phn xtng in ly, lp F1 v lp F2A. Sng diB. Sng trung C. Sng ngnD. Sng cc ngn

2. iu khin thphng hng theo phngphn pha, d=/2, mun bp sng qut ht na mtphng:A. Gc pha phi thay i t0 n /2B. Gc pha phi thay i t0 n C. Gc pha phi thay i tn -D. Gc pha phi thay i t-n

3. Cp ng trc c thc sdng tip incho anten chn ti xng khi thc hin:A. Phi hp trkhng dng bbin i chUB. Phi hp trkhng dng bbin i dng ccC. Phi hp trkhng mt cch ttD. C3 cch trn

4. Hssng ng trn mt ng truyn ni mt phtvi anten sc gi trSWR=1, khi:A. Trkhng c trng Zc ca ng truyn bng

trkhng vo ca anten ZvB. ng truyn ngn mch (Zt=0)C. ng truyn hmch (Zt=)D. C3 trng hp trn u khng ng

5. Hai chn ti xng t vung gc vi nhau, dngin trong hai chn tc cng bin nhng khc

pha nhau 90 . Trong trng bc xca hai chn t trong mt phng cha hai chn tsc phn ccA. TrnB. Thng C. ElipD. Phn cc quay

6. La chn mt trong 4 loi anten sau y c hsnhhng cao nht ( so snh trong cng mt di tn):

A. Anten loga chu kB. Anten sng chy C. Anten gng parabolD. Anten Yagi

II.

PHN TLUN: (7 im)Cu 1:(2 im) Ttrnh by anten Tuanile trong truyn hnh ( cu to, nguyn l c tnh bc x, tipin v ng dng). Ti sao khi sphn tca dn anten Tuanike chn v khong cch gia cc phntl /2 th trng bc xca dn anten theo hng trc li bng 0 ?Cu 2:(2 im) Truyn sng trc tip trong tm nhn thng c nhng u im v hn chg. Cchkhc phc hn ch. Ti sao khi tnh ton ng truyn sng cc ngn phi tnh n min Fresnel. ngha ca vic tnh ton .Cu 3:(3 im) Cho tuyn xung bng Ku ca hthng thng tin vtinh Vinasat_1 c cc thng ssau:

- Tn stuyn xung 12 GHz. Tn hao do ma v pha inh ton tuyn l 10dB.- Bqua tn hao ghp ni ga bkhuch i v anten (ctrn vtinh v di trm mt t)- Vtinh: cng sut ca bkhuch i pht: P=40W; anten parabol c hstng ch GT[dB]=38 dB- Trm mt t ti tp.HCh Minh: khong cch tvtinh Vinasat_1 n trm mt t t ti thnh

phHCh Minh R=36.640 km. Anten Parabol c hiu sut =0,6. nhy my thu -100dBYu cu:

a. Tnh cng sut bc xng hng tng ng ca vtinh EIRPb. Tnh tn hao trong khng gian tdo khi sng truyn lan tvtinh xung trm mt tc. Tnh ng knh anten thu ti trm mt t m bo thu tt

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