Ly Thuyet Truong Anten Dh

8/13/2019 Ly Thuyet Truong Anten Dh

1/230

Tn hcphn:L thuyttrnganten

Tnglngkinthc:2 tc

Mctiu hcphn:Gii thiu cc khi nim, cc biu thc ca qu trnh truyn lan sng vtuyn. Nghin custruynlan casng ccngntrong mi trngthc

Gii thiu l thuytchung vanten, cc anten nguyn t. Nghin cuhotngcachntixng, cc loianten trong thng tin v tuyn


2/230

Nidung hcphn:

Chng1: Cc vnchung vtruynsngTnh chtcasng int; Ccphngphp truynlan sng; Qu trnh truynlan sngtrong khng gian tdo

Chng2: Truynlan sng ccngn

Truynlan trong iukinl tng; Truynlan trong iukinthc

Chng3: Knh truynsng v tuyn

ctnh knh truynsng; Phadinh; Cc m hnh knh

Chng4: L thuytchung vanten

Cc tham scaanten; Cc ngunbcxnguyn t

Chng5: ChntixngTrngbcxcachntixng; Cc tham s,phngphp cpincho chntixng

Chng6: Anten trong thng tin v tuyn

Anten nhiuchnt; Nguyn lbcxmt; Anten loa, anten gng


3/230

Ti liutham kho:[1]NguynPhmAnh Dng, PhmThThy Hin, Truynsng - Anten, Biging, Hcvincng nghBCVT, 12/2006

[2] Phan Anh, Trngintv truynsng, NXB ihcQucgia HNi,

2002[3] Phan Anh,L thuytv kthutanten, NXB KHKT, 2004

[4] Robert E.Collin,Antennas and Radio wave propagation, PrenticeHall


4/230

CC VN CHUNGV TRUYN SNG

CHNG 1


5/230

Nidung chng1:1.1 Giithiu

1.2 Tnh chtcbncasng int

1.3 Phn loisng int

1.4 Phngthctruynlan sng int1.5 Biuthctruynlan sng trong khng gian tdo

1.6 Hssuy gim

1.7 Cu hiv bi tp


6/230

Hthngvinthng

Hnh 1.1. M hnh hthngvinthng


7/230

Truyndnv tuyn(Radio Transmission)

Mi trngtruyndn

Khng gian (bukh quyn)

Phngtintruyndn

Sng int

Hnh 1.2. Mi trngtruyndnv tuyn


8/230

Khi nimSng intl qu trnhbininnglngtunhon giaintrngvttrnglm cho nnglngintlan truyntrong khng gian.

cim

Sng intc hai thnhphn:intrng: E (V/m)

Ttrng: H (A/m)

yl hai ilngvect(cphng, chiu, ln), c quan hmtthitvinhau trong qu trnh sng truynlan trong khng gian

Cc ngunbcxsng intthngc dngsng cuhocsng tr, khinghin cuta chuynvdngsngphng


9/230

Biuthcquan hgiacc thnhphnNghin cuvisng intphng, truynlan trong mi trnginmingnhtv nghng

Biudinsng intbnghphngtrnh Maxoel dngvi phn:

Giih

yx

yx

HE

t z

HE

z t

: H s in mi: H s t thmz: C ly truyn sng

t: Thi gian

(1.1)

x 1 2

y 1 2

E F

G

z zt F tv v

z zH t G t

v v

F, G: Cc hm sngv: Vn tc truyn lan ca sng (m/s)

vz 1

t .

(1.2)


10/230

Biuthcquan hgiacc thnhphnTrkhng sng, Z: Biuthnhhngcami trngtiqu trnh truynsng

Vikhng gian tdo

(1.3)

(1.4)

ZE

H

97

0 0

8

0 0

00

0

v

104 .10 H / m ; F/ m36

13.10 m /s c

Z 120


11/230

Biuthcquan hgiacc thnhphnBiniFourierbiudinsng intdidngtn hiuiuha

Nhnxt: Khi sng truynlan, timiimthnhphnttrngv intrngc pha nhnhau v bin lin hqua cng thc(1.5)

(1.5)

x m m

m m

y

E E

H

zcos t E cos t kzv

E Ezcos t cos t kzvZ Z

2 .f 2 .f 2k

v c f .

k: H s sng, c trng cho s thay i pha ca sng


12/230

Biuthcquan hgiacc thnhphn

Thng lngnnglngcasng int, S

Thng lngnnglngtrung bnh

Sng intngang, TEM

(1.6)[ ]S E H

2

m m mavg e

1 E .H ES R E H

2 2 2.Z

2W/m

Hnh 1.3. Sng TEM

(1.7)


13/230

MtsngSng intlan tatrong khng gian, timiimsng intcctrngbipha v cng

Mtsng: L qutch nhngimtrong khng gian tisng intcpha nhnhau v cngbngnhau

Hai dngmtsng cbit: Mtsngphng, mtsng cuQu trnh truynlan sng int: Tnh chtsng

Sng intbcxra khng gian didngv scc mtsng lin tip

Ngunbcxsng intchngvai tr l ngunbcxscp

Qu trnh sng truynlan, cc mtsng ctora ngvai tr l ngunbcxthcptora cc mtsng tipsau n


14/230

Phn ccsngKN: Trngphn ccl trngintvicc vecto E v H cthxc nhchngtithiimbtk(binic tnh

quy lut)Ngclil trngkhng phn cc(biningunhin trong

khng gian)

Mtphngphn cc: L mtphngchavec tE vphng

truynlan sng (vecto Z)


15/230

Phn loi Phn ccngthng: Mtphngphn cccnhkhi sng truynlan

Phn ccng: Vecto E vung gc vimtphngnmngang

Phn ccngang: Vecto E song song vimtphngnmngang

Phn ccquay: Mtphng phn cc quay xung quanh trccaphngtruynlan

Phn vctrn: Khi vecto E quay, bin khng thay i (v ln ngtrn)

Phn ccelip: Khi vecto E quay, bin thay i lin tcvln ngelip

Quayphi: Quay thunchiukim nghQuay tri: Quay ngcchiukim ngh


16/230

Phn ccsng

Hnh 1.4. Cc

dng phn ccsng


17/230

Phn chia sng intDavo tnh chtvtl, cimtruynlan: Chia thnh ccbngsng

Hnh 1.5. Cc bng

sng


18/230

Phn chia sng intDavo tnh chtvtl, cimtruynlan: Chia thnh ccbngsng

Bng1.1. Cc bngsng

Tn bngtn(Bngsng) K hiu Phm vi tn s

Tnsv cng thp ULF 30 - 300 Hz

Tnsccthp ELF 300 - 3000 Hz

Tnsrtthp VLF 3 - 30 kHz

Tnsthp(sng di) LF 30 - 300 kHz

Tnstrung bnh (sng trung) MF 300 - 3000 kHz

Tnscao (sng ngn) HF 3 - 30 MHz

Tnsrtcao (sng mt) VHF 30 - 300 MHz

Tnscccao (sng decimet) UHF 300 - 3000 MHz

Tnssiu cao (sng centimet) SHF 3 - 30 GHz

Tnsv cng (sng milimet) EHF 30 - 300 GHz

Dimilimet 300 - 3000 GHz


19/230

Phn chia sng intTnh chtquang hc

Sng nh sng cngl sng int, bngtnthgic cmnhnc, khi nghin cusng intthngsdngsng nh sng cho trcquan

Cc tnh chtquang casng nh sng cngngcho sng int

TruynthngPhnx, khc x

ngdngccbngsngLF, MF: Pht thanh iubin nia, thng tin hng hi

HF: Pht thanh iubin cly xaVHF, UHF: Pht thanh iutn(66108 MHz), truynhnh, viba sbnghp, hthngthng tin di ngmtt

SHF: Viba sbngrng, thng tin vtinh

EHF: Thng tin vtr


20/230

Bukh quyn

Hnh 1.6. Phn tngbu

kh quyn


21/230

Sng tNguyn l

Bmttri tl mi trngdnkhp kn ngscintrngNgunbcxnm thngngtrn mtt, sng in t truyn lan dc theo mttnimthu

cimNnglngsngbhptht ivitnsthp, cbitvimttm, mtbin(dnln)Khnngnhiuxmnh, cho php truynlan qua cc vtchnSdngchobngsng di v trung viphn ccng

ThuPht

A B

Hnh 1.7: Qu trnh truyn lan sng t (sng b mt)


22/230

Sng khng gianNguyn l

Anten tcao trn mttt nhtvibcsng

Sng intnimthu theo 2 cch

Sng trctip: ithngtimpht nimthuSngphnx: nimthu sau khiphnxtrn mtt(thamn L PX)

cim

Chunhhngnhiucaiukinmi trng

Ph hpchobngsng ccngn, lphngthctruynsng chnh trong thng tin

v tuyn

Hnh 1.8: Truyn lansng khng gian


23/230

Sng tnginly (sng tri)

Nguyn lLidngctnhphnxsng catnginly viccbngsng ngn

Sng intphnxsquay trvtri t

cim

Khng nnhdo sthay iiukinphnxcatnginly

Hnh 1.9: Truyn lansng tng in ly


24/230

Sng tdo (sng thng)

Nguyn lMi trngtruynsng l tng(ngtnh, nghng, khng hpth)

Sng truynlan trctipnimthu theo mtngthng

cimMi trngchtntitrong vtr, sdngcho thng tin vtr

Bukh quyntri ttrong mtsiukinnhtnhccoi l khng gian tdo

Hnh 1.10: Truyn lan sng t do

Mc tiu trong v tr

Trm trn mt t


25/230

Tngkt:

Hnh 1.11: Cc phng thc truyn lan sng v tuyn

Sng t do

Sng tri

Sng t Mt t

Khng gian t do

Tng in ly

Tng bnh lu

Tng i lu

Sng khng gian


26/230


27/230

Mtcng sut, cngintrngTheo l thuyttrng

Cngintrngtiimthu

(1.9)

h h

2 h h h 0

2

h2

E ES E

ES

.H ; HZ 120

120

Eh, Hh: Cngintrng, ttrnghiudng

Z0: Trkhng sng cakhng gian tdo

1h 2

1

h

E30P

r

60.P

E E . 2.cos t kr .cos t kr r

V/m

V/m

(1.10)


28/230

Mtcng sut, cngintrngSdnganten c hng

Tpchung nnglnggip tngcng suttiimthu

ctrngbihstnh hngD1

(1.11)

'

1 21 1'

1 2

1 11 12 2

;

60. ... . .

4 .

P PD D

P P

P DP DS E cos t k r

r r

Hnh1.13: Ngun bc x c hng

R; P2

bc x v hng

T; P1

R; P2

P2


29/230

Cng sutbcxnghngtngng(Equivalent Isotropic Radiated Power - EIRP)

G(dBi) = 10 log G nn liG = 10 ^ ( G(dBi)/10 )

L cng sutbcxtngngcamtanten v hngc thtc

cngtrngtiimthubngvikhi dng anten c hng

G1: Hstngch anten pht (GT)1: Hiusutanten pht (T)P1: Cng sutbcxanten pht (P)Pa1: Cng sutavo anten pht (PT)

(1.12)

1 1

1 1

11 1 1 1

1

1 1

.

; .

. .

dB dB

a

a T T

EIRP P D

EIRP P D dB

GD P P

EIRP P G P G

(1.13)


30/230

Cng sutnhnctrn anten thu, P2

L tch giamtcng suttiimthu, S

2v dintch lm viccaanten thu, A

Trnghpsdnganten gngparabol trn xoay vihstnh hngD2

Cng sutthctura anten thu

Ah: Dintch hiudngcaanten thu2: Hiusutanten thu

(1.15)

2 2.P S A

2 22

22

22

2 1 12 1 1 22

.. .;

4 4.

. .. . . . W

4. 4. . 4. .

Dd dA D A

D P DP P D D

r r

2 2 2. ; .a h hP S A A A (1.16)

(1.14)

d: ngknh minganten

: Bcsng cng tc


31/230

Tnhao truynsng, L

Xc nhbng tsgiacng sutbcxcamy pht vi cng sutanten thunhnc

Tnhao truynsng trong khng gian tdo gy rabiskhuch tn ttyuca

sng theo miphng, cng sutthu cchl mtphnnh. Tnhao ny gilTnhao khng gian tdo, L

td

Trnghpsdnganten v hng, gil tnhao cbntrong khng gian tdo,L

0

1

2

PL

P

2

1 2

4 . 1.

.td

rL

D D

(1.17)

(1.19)

(1.18)

2

0

0

1 2

4 .

20lg 20lg 92,45

20lg 20lg 92,45 10lg 10lg

GHz km

td GHz km

rL

L f r dB

L f r D D dB

(1.20)


32/230

Hssuy gim, F

Mi trngthctc nhiuyutnhhngtiqu trnh truynsng, nhhngticng sutthu

Cc nhhngcami trngthcln qu trnh truynsng cbiudinqua hssuy gim: F

Trong mi trngthc

2

1 2

4 . 1

.. .tdr

L F D D

(1.24) 1 220lg 20lg 92,45 10lg 10lg 20lgtd GHz kmL f r D D F dB

21 12 2

..

4 .

P DS F

r 1hE

30P.F

rV/m

(1.23)

(1.22)(1.21)


33/230

Bi tpchng1

1.Mt tri c cng sut bc xtheo mi hng khong 3,85.1020W, khong cch nhnht tqut n mt tri l 147.098.090 km (vo thng ging) v ln nht l 152.097.650 km. Tnh:

- Mt cng sut bc xcc tiu v cc i ca mt tri ln bmt qut?

- Mt cng sut bc xmt tri khong cch trung bnh v tlphn trm sai sca

bc xcc i v cc tiu so vi gi trtrung bnh?2.Mt my pht c cng sut 3 W, anten pht c hskhuch i l 30 dBi. cly 40 km tmt anten thu c din tch hiu dng l 3,5 m2, hiu sut lm vic 100%. Tnh cng sut sngmang nhn c anten thu.

3. Xc nh cng sut my pht cn thit thc hin tuyn thng tin c cc iu kin: c lythng tin 50 km, tn scng tc 2GHz, hskhuych i ca anten thu v anten pht l 30 dBi,cng sut anten thu nhn c l 10-6W.

4.Mt my pht c cng sut 50 W. Biu din cng sut my pht sang n vdBm v dBW?


34/230

Bi tpchng1

5.Cng sut bi 4 c cp cho anten v hng lm vic vi sng mang c tn s900 MHz, tmcng sut thu (tnh theo dBm) ti im cch anten pht mt khong 10 km. Gisanten thu c hskhuch i l 2 v sng truyn trong khng gian tdo.

6.Sliu nh bi 4 v 5, tnh bin cng in trng hiu dng ti im t anten thu.

7.Tnh tn hao khi truyn sng trong khng gian tdo (theo dn vdB) bit cly truyn sng 50

km, tn scng tc 2 GHz, vi anten v hng.

8.Sliu nh bi 7, nu chai anten c hskhuych i l 30 dBi th tn hao l bao nhiu?

9. Mt m y pht c cng sut l 100W ni v i anten c hs khuch i 10. Xc nh cng sutbc x ng h ng tng ng tnh theo W, dBW, dBm?

10. Mt anten c tr khng bc x 73 ,tr khng tn hao 8 , hs hngtnh 20, cng sutmy ph t tvo anten 100W. Xc nh:

a. Hiu sut lm vic ca anten.

b. Hs khuch i ca anten (dBi).

c. Cng sut bc x v cng sut bc x ng h ng tng ng W, dBW, dBm.


35/230

Bi tpchng1

12.Mt ngun v hng c cng sut bc x100W. Mi trng truyn sng l khng gian tdo.

Hy xc nh:

a, Mt cng sut ti im cch xa ngun 1000 m.

b, Mt cng sut ti im cch xa ngun 20 km.

13.Xc nh cng in trng hiu dng ti im thu vi cc githit cho trong bi 13.

14.Xc nh mt cng sut ti im cch anten 30 km ca mt anten c cng sut bc x5 Wv hskhuch i ca anten l 40 dBi.

15.Mt anten pht c hskhuych i 30 dBi, hiu sut lm vic 60%. c cng in

trng hiu dng ti im thu cch anten pht 100 km bng 3,46 mV/m th cn phi a vo antencng sut l bao nhiu? Vi iu kin sng truyn trong khng gian tdo.


36/230

CHNG 2


37/230

Nidung chng2:

2.1 TngQut

2.2 Truynlan trong giihnnhn thytrctipviiukinl tng

2.3 nhhngcacong tri t

2.4 nhhngcaahnh

2.5 nhhngcatngilu

2.6 Cu hiv bi tp


38/230

cimtruynlan sng ccngnBcsng t1mm n10m (30MHz300GHz): L sng siucao tn(RFRadio Frequency)

Phngphp truyn

Tnscao nn khng thphnxtrong tnginly (ixuyn qua)Bcsng ngnnn khnngnhiuxkm,bhpthmnhbimtt

Phngphp truynsng khng gian: L ph hpnht

Tn xtngilu

Siu khc xtngiluTruynlan trong giihnnhn thytrctip


39/230

cimtruynlan sng ccngn

Tn xtngiluTnticc vng khng gian khng ngnhttrong tngilu

Sng ivo trong vng khng ngnhtskhuychtn theo mihng

Lidngtruynsng nimthu

cim: Khng nnhdo vng khng ngnhtlun thay i

Hnh 2.1: Tn x tng i lu


40/230

cimtruynlan sng ccngn

Siu khc xtngilu

ChschitsutN gimtheo cao.

Khi tcgimtdN/dh < -0,157 (m-1)Tia sng c bn knh cong lnhncong tri tnn quay trlimtt: Siu khc x

Lidngtruynsng nimthu sau khiphnxnhiulntrn mtt

cim: Khng nnhdo minsiu khc xlun thay i

Hnh 2.2: Siu khc x tng i lu

1

2

3

45 45

4

gh

h0A


41/230

2.1 Tngqutcimtruynlan sng ccngn

Truynlan trong giihnnhn thytrctipHai anten thu v phtphictcao trn mtttrnhbche chnbiccvtcntrn ngtruynhay cong catri t

Sng truyntpht nthu trong minkhng gian nhn thytrctipgiahaianten

cim: tphthucvo iukinthin nhin, sdngphbin

Hnh 2.3 Truyn lan trong gii hn nhn thy trc tip


42/230


43/230

Cngintrngtiimthu

Tnghpcngtrnghai sng thnhphn(giao thoa)

Cngtrngdo tia trctip

Cngtrngdo tiaphnx

R 1 2

T1T kW j t

1

1 km

T2T kW j t k r

2

2 km

E

E

E E E

245. P G

er

245. P GR e

r

mV/m

mV/m

r1: on ng i ca tia ti trc tip; r2: on ng i ca tia phn x

r: hiu sng i ca hai tia r = r1-r2; k : hssng (= 2/)

R: hsphn xphc tmt t: jR Re , R: m un, gc sai pha

GT1 v GT2: hskhuch i ca anten pht theo hng tia trc tip v tia phn x

(2.1)

(2.2)

(2.3)


44/230

Cngintrngtiimthu

Do chiucao anten hT, hR


45/230

Cngintrngtiimthu

t= + k.r: Gc sai pha ton phn. Chuyndnghm msang hm lnggic

Cngintrngtngtiimthu

Hssuy gimtrong trnghpmttphng

21 . 1 .cos .sin 1 .cos .

.sin1 .cos

j jR e R jR R R e

RtgR

2

TT kW j t

km

TT kW 2h

km

2

E

E

245. P G . 1 2R cos R .e

r

173. P G . 1 2R cos R r

F 1 2R cos R F 1 R F 1 R

mV/m

mV/m

(2.7)

(2.8)

(2.9)

(2.10)


46/230

CngintrngtiimthuVituynxc nh: h

T, h

R, , , c thxc nhcly thng tin r c hs

suy gimtcctr

Cciti (+ k.r) = 2n. vin = 1,2,Cctiuti(+ k.r) = (2n + 1). vin = 1,2,


47/230

CngintrngtiimthuHiusngigiahai tia

B

B

hr-ht

Tia 2

Tia 1

C

A

ht

hr

hr+ht

r

hr

22 2 2

1 r t

2 22 ' 2

2 t r

2 22 2

2 1 2 1 2 1 t r r t

t r

r AB h h r

r AB h h r

r r r r . r r h h h h

2h hr m

r

(2.11)

Hnh 2.5 Xc nh hiu s ng i giahai tia


48/230


49/230

Cngintrngtiimthu

Xc nhimgiao thoa tcctr

Cci

Cctiu

T R T R

T R

T Rn_max

2 .h .h 2 .h .hsin 1 sin 1r. r.

2 .h .h 2n 1 . n 0,1,2,...r. 2

4.h .hr m

2n 1 .

T R T R

T Rn_min

2 .h .h 2 .h .hsin 0 n 1 . n 0,1,2,...r. r.

2.h .hr m

n 1 .

(2.15)

(2.16)


50/230

Cngintrngtiimthu

Cng thcVvedensky

Visin() = (rad)

khi < 200, nn

Cng thcVvedenskyxc nhcngintrngticly

T R

T R

TT kW T m R m

h 2

km m

r.h .h18

4 .h .hF.r

2,18. P .G .h .hE mV / m

r .

T R18.h .hr

(2.18)

(2.17)

(2.19)


51/230

Stuynthng tin khi kncong tri t

nhhngcacong tri tHiusngigiasng trctipv sngphnxthay i

imphnxlinn c tnh tn xHsphnxnh

Hnchtmnhn trctipgiaanten thu v pht

A

B

A1 B1C

O

a

hrht

hthr

Hnh 2.7 M hnh truynsng trn mt t cu


52/230

Cly nhn thytrctip, cngintrngtiimthu

Cly nhn thytrctipr0L cly lnnhtc thnhn thycvianten c cao h

T, h

R

Cng thcthcnghim

(r0= r, cly dctheo mtt)

O

hrh

t

A B

a

ro

C

0

2 2 2

t t t t t

2 2

r r r

0 t r

0 t m r m

r AC CB

AC a h a 2a.h h 2a.h h a

CB a h a 2a.h h a

r 2a. h h m

r 3,57 h h km

(2.20)

(2.21)

Hnh 2.8 C ly nhn thy trc tip


53/230

Cly nhn thytrctip, cngintrngtiimthu

CngintrngQu trnh truynsng cly nhhncly nhn thytrctip

Tngtnhmttphng, chiucao anten xc nhbngchiucao ginh: ht, h

r

Gi trchiucao anten ginhxc nhbnghsb m (tra theobnghocth)

' '

t r t r

t r

t r

TT kW t m r m

h 2

km m

E

h .h m.h .h

2.m.h .hr m

r

4 .m.h .hF

.r

2,17 P G .m.h .hmV/m

r .

(2.22)

(2.23)

(2.24)

(2.25)


54/230

gghcatri t(tiaphnx)

nhhngghcatri tHintngtn x

Tiu chunRayleigh

Khi tiu chunRayleigh thamn

sphnxsng khng c tnh tn xMttcoi lphng

h m

8sin

B

B

C

C

A

A

h

Tia B

Tia AMt sng 1

Mt sng 2

h: cao ca mt t phng gi

nh so vi mt t thc

: Gc ti ti im phn x

(2.26)

Hnh 2.10 M hnh tiu chun Rayleigh

Hnh 2.9 Mt ct ngang a hnh thc


55/230

Nguyn l Huyghen, minFresnel (tia trctip)

Nguyn l HuyghenNhnxt

Bnchtintcasng nh sng

Tnh chtsng casng intkhi truynlan

Nguyn l: Miimnmtrn mtmtsng do mtngunbcxsng ints

cpgy ra strthnh ngunbcxthcpmi.Ngunbcxthcpminylitora cc mtsng thcpmikhc.Nhvytrnginttimtimtrong khng gian do mtngunbcxscpsinh ra sdo tonbvng khnggian bao quanh ngunbcxscpgy ra.

S r

A

M

Hnh 2.11: Xc nh trng theo nguyn l Huyghen


56/230


Nguyn l Huyghen

nghaQu trnh truynsng inttimpht nimthu khngphichtheo mttia m cngtrngtiimthu l do tonbminkhng gian bao quanh impht gy ra

C thxc nhcngtrngtimtimbtktrong khng gian khibitmttrngcamtsng tora n.

C

A

A

B B

Hnh 2.12. Biu din nguyn l Huyghentrong khng gian t do


57/230


MinFresnelXy dngminFresnel

Khi nim

Nn

r1

A B

Nn

N0

r2

N0

N1N2

N4

+++ + +

++

++

+

+

+ ++

+

+

+

+

+

+

++ +

+

+

+

+

-

-- -

-

--

--

--

-

- -

-

-

--

N3

N1

N1

+ Dngmtsng iqua N0+ Dng mt nn trn xoay trc BN0,

ng sinh l: (BN0 + n./2), ct mtsng Nn

+MinFresnel thn (Fn) l vng khng gian cgiihnbiqutch

cc imm hiusgiatngkhongcch timny nimpht

v imthu vikhongcch giahai imthu pht l hngsc gi

trbngn lnnabcsng cng tc.

n nAN N B AB n. 2 + MinFresnel c dngelip trn xoay nhnhai imthu v

pht lm tiu im,c bn knh l bn

(2.27)

Hnh 2.13: Nguyn l cu to minFresnel trn mt sng cu


58/230


MinFresnelTnh bn knh b

n

Cng thchpl ha

n n 1 2

2 22 2 n n

n 1 n 1 1 n 12

1 1

2 22 2 n n

n 2 n 2 2 n 22

2 2

2 2

n n1 2 1 2

1 2

1 2

1 2

1( km ) 2 (km )

1 2 GHzkm

AN BN r r n.2

b bAN r b r . 1 r b r

r 2r

b bBN r b r . 1 r b r

r 2r

b br r r r n.

2r 2r 2

r .rb .n. m

r r

r .r .nb m

r r .f

n

n

=

= 17,32.

(2.28)

(2.29)

Hnh 2.14: Xc nh bn knh min Fresnel

b1max

BA

Hnh 2.15: Vng tham gia vo qu trnh

truyn lan sng

B

Nn

A

bn

S0

N0

r1 r2


59/230


MinFresnelChngminh c rng: Cng trng ti im thu chyu cgy ra bivng khng gian nmtrong khongmtnaminFresnel thnht(0,6b

1). Tng

cngtrngdo cc imnmngoi minny gy ra tiimthu sb trchonhau v trittiu do pha cachng ngcnhau. yl giihncavng truynsng trongphmvi nhn thytrctip

ngha

Qu trnh truynsng v tuyngiahai anten thu v pht khng phich theo mt tia,cngkhngphido tonbminkhng gian m chl vng khng gian c dngelip trnxoay nmtrong khongmtnaminFresnel thnht

Qu trnh truynsng v tuyncbn tn tikhi vng khng gian giihnbi0,6 b1

khngbcntrsutdcngtruynqu trnh pht v thu sng v tuynthiuqucao, ta dng ccbinphp kthutsng in tbc x ra ch tp chung trong min Fresnel thnht sdng anten chng(anten parabol)


60/230

Chitsut(n), chschitsut(N)

Chitsut, n, catngiluxpxbng1, trong tnh ton mbochnhxc cao ta sdngchschitsutN

Tngilukhng ngnht, cc thng sthay itheo khng gian v thigianchitsutthay i

Tcthay ichschitsuttheo cao nhhngtiqu trnh sng truynlan: Quosngbcong do hintngkhc x: Hintngkhc xkh quyn

'

'

6

c 1n 1v 2

N 10 . n 1

dN 1/dhm A

B

C

(2.30)

Hnh 2.16 Qu o ca tia sng trc tip v tiaphn x t mt t trong tng kh quyn thc


61/230

Bn knh cong casng

Nguyn tc

Bn knh cong

Qu o sng

d

+ d

R

O

c

a

b

dh

n = const

n + dn = const+ Chia tngiluthnh cc lpmng

vidy dh, chit sut thay imt

lngdn

+ Cung AB nm trn ng trn bn

knh R, gc chntm d

6

0t r

abR

d

dh dh dhab d R

c c c .d

sin .dn

n.sin n dn .sin d c . n

n 1 10R R h , h r 90 ; n 1

dn dNdnsin .

dh dhdh

os +d os os

os d

+ dN/dh > 0 R < 0; dN/dh < 0 R > 0; dN/dh = 0 R = (2.31)

Hnh 2.17 tnh bn knh

cong tia sng


62/230

Phngphp tnh cngintrng

Bn knh tngngcatri t, atdMttthcbn knh a = 6.378 km, tia sngbkhc xvibn knh cong R

Mttc bn knh atd

, tia sng ithng(R = )

Bn knh atd

phithamn iukin: cong tngigiamttv tia sngkhng i

Bn knhtri t

Bn knhcong quo

a)

a

R

b)

at

td6td

2 1td

1 1 1 1 a aaa dNa R a

1 1 a .10R dh

dN4.10 m a 8.500km

dh

(2.32)

Hnh 2.18 Cc qu o ca sng v tuyna) Qu o thc vi tri t bn knh thc

b) Qu o ng thng vi tri t c bn knhtng ng


63/230

Phngphp tnh cngintrng

Hscong tia sng, k

Cly nhn thytrctip

litri t

td

6

a 1k

dNa 1 a .10dh

'0 t rr 2k.a h h m

1 km 2 kmr .rB m

12,74.k

(2.33)

(2.34)

(2.35)


64/230

Loikhc x(1/m)

R (m) at (m) Qu o sng thc tQu o sng tng

ng

Khc xm >0 < 0 < 6,37.106

Khng khc x 0 6,37. 106

Khc xthng - 0,04 2,5. 107 8,5. 106

Khc xtihn - 0,157 6,37. 106

Siu khc x < - 0,157 < 6,37. 106 < 0

dN

dh

atd= a

a

atd= aa

atd< 4a/3

a atd< a

a atd< 0


65/230

Hpthsng trong tngilu

Nnglngsngbhpthdo cc phn tkh, ma, sngmHpthphthucvo tns, thay itheo khng gian, thigian

Hpthphn t

Chyudo phn tncv xy

Phthucthiuvo tns

cbittngnhanh vitnstrn 10GHz

3 6 15 30 60 150 300

10+2

10+1

100

10-1

10-2

10-3

Tn s GHz

SuyhaodB/km

f = 22 GHz

O2

H2

O

Hnh 2.19. S ph thuc ca h s hp th sng ca

O2v H2O vo tn s


66/230

Hpthsng trong tngilu

Hptrong mav sngmHp thtrong maph thucvo cngmatnh theo mm/h, v theo tns,tngnhanh vitnst6GHz trln

Hpthdo sngmphthuc

theo tnsv tmnhn xa caanten

Gy thay iphn ccsng

6

8 10 20 30 40 50 60 100

23

4

8

40

30

20

10

Tn s GHz

HpthdB/km

41 m 150 m

Hp th dB/km

0,010,1

1

10

10 30 10031 Tn s GHz

30 m

Hnh 2.21. S ph thuc ca h s hp th trong mavi cng ma 100 mm/h vo tn s

Hnh 2.20. S ph thuc ca h s hp th trongsng m theo tm nhn xa v tn s


67/230

Bi tpchng2

9. Cho ng truyn c cc thng ssau: Cng sut bc x15 W, bc sng cng tc 35 cm, hskhuch i ca anten pht l 100, cao ca anten pht v anten thu ln lt l 80 m v 20 m,

cly ng truyn l 10 km. Vi R = 0,91 v = 1800khi sng phn cc ngang v R = 0,68; =1800khi sng phn cc ng. Xc nh hssuy gim?

(a) 0,42 v 0,44; (b) 0,52 v 0,54; (c) 0,62 v 0,64; (d) 0,72 v 0,74

10. Sliu nh bi 9, xc nh cng in trng hiu dng ti im thu?

(a) 10 mV/m v 11,5 mV/m; (b) 11 mV/m v 10,5 mV/m; (c) 11 mV/m v 11,5 mV/m; (d) 10,5mV/m v 11,5 mV/m

11. Sliu nh bi 9, xc nh tn hao truyn sng bit hskhuch i ca anten thu l 100.

(a) 76,78 dB v 76,45 dB; (b) dB; (c) 76,78 dB v 80,45 dB; (d) 80,78 dB v 80,45 dB

12. Xc nh hssuy gim khi ng truyn c cc tham s: cng sut pht 50 W, bc sngcng tc 10 cm, hskhuch i anten pht 60, cao anten pht 25 m, anten thu 10 m, c ly

truyn sng 10 km, hsphn xR = 1 v = 1800

.(a) 1,62 ; (b) 1,72; (c) 1,82; (d) 1,92

13. Sliu nh bi 12, xc nh cng in trng ti im thu?

(a) 115,34 V/m; (b) 125,34 V/m; (c) 115,34 mV/m; (d) 125,34 mV/m


68/230

Bi tpchng2

14. Sliu nh bi12 nhng bc sng cng tc l 1m. Hy xc nh cng in trng tiim thu?

(a) 15 mV/m; (b) 16 mV/m; (c) 17 mV/m; (d) 18 mV/m

15. Mt anten pht c t cao 49m v anten thu c t cao 25m. Khong cch tmnhn thng ca hai anten ny l gi trno di y?

(a) 35,8 km; (b) 42,8 km; (c) 45,8 km; (d) 50,8 km

16. Mt anten pht c t cao 30m v anten thu c t cao 15m. Khong cch tmnhn thng ca hai anten ny l gi trno di y?

(a) 27,4 km; (b) 30,4 km; (c) 33,4 km; (d) 35,4 km

17. Anten pht v tuyn truyn hnh t cao 64m. Tnh cao ca anten thu ti mt im tcch xa i pht mt khong 50 km c ththu c tn hiu.

(a) 2 m; (b) 2,5 m; (c) 3 m; (d) 3,5 m

18. Xc nh bn knh cong ca tia sng khi i trong tng i lu i lu tiu chun?(a) 2.106m; (b) 2,5.106m; (c) 2.107m; (d) 2,5.107m


69/230

CHNG 3


70/230


3.2 ctnh knh trong cc min

3.3 Pha inhphmvi hp

3.4 PhnbRayleigh v Rice3.5 Cc m hnh knh

3.6 Phn tp

3.7 Cu hiv bi tp


71/230


72/230

Cc yuthnchtmi trngv tuynSuy hao: Tngtheo khongcch, gi trt50 n150dBChe ti: Cc vtcntrn ngtruynlm suy gimtn hiu

Phadinh ang: Tn hiutrctip,phnx, nhiux, tn xgiao thoa vinhau gy mo tn hiu(thay icngtn hiu;Nhiugiao thoa giacc

k hiuISI, InterSymbol Interferrence, do phn tn thigian)Nhiu: Trng tn s (CCI CoChannel Interference), knh ln cn (ACI Adjacent Channel Interference)


73/230

Phn loiknh v tuyn

Theophmvi khng gian

Phadinhphmvi rng

Khongcch nhgi knh ln(vi km), phadinh xyra trong thigian di

Phadinhphmvi hp

Khongcch nhgi knh nh, Phadinh xyra trong thigian ngn(phadinh nhanh, dohintngang)

Theo ctnh knh

Phn tpkhng gian: c tnh knh thay i theo khng gian (phadinh chn lckhng gian)

Phn tptns: ctnh knh thay itheo tns(phadinh chnlctns)

Phn tp thigian: c tnh knh thay i theo thigian (phadinh chn lc thigian)


74/230

nhhngphmvi rngSuy hao ngtruynv che ti.

Chng ngi

My pht My thu

txP rxP

d


75/230


76/230

Minh hactnh caknh

Tnh chn lc khng gian ca k nh

Bi n

Min khng gian

Tnh chn lc tn s ca k nhBi n

Min tn s

Tnh chn lc thi gian ca k nh

Bi n

Min thi gian

Hnh 3.1; 3.2; 3.3: Tnh chtknh trong minkhng gian, mintns,minthigian

Hnh 3.1 Hnh 3.3Hnh 3.2


77/230


78/230


79/230

Minthigian

Cc knh v tuynthay itheo thigian (phadinh chnlcthigian)Biudintn hiuthu

x(t): Tn hiupht : Trangh(t,): pngxung kim knh v tuyn

nhhngangknh v tuynl tri tr(phn tn thigian), nghim trngvicc hthngtccao

( ) ( ) ( , ) ( ) ( , )y t x h t d x t h t

(3.4)

"0"

"1"

"0" "1"

Hnh 3.5 nhhngcatritr


80/230

Minthigian

Tritrtrung bnh qunphng, RDS (Root mean square Delay Spread)

P(k): Cng suttrung bnh angtithiimkRDSbiuthtrso vingnsmnht(LOSLine Of Sight)

RDS nhgi nhhngcaISI (InterSymbol Interference)

( ) ( )

( ) ( )

k k k

k k

k k

k k

kP P

P P

2 2

2

2(3.6)

(3.5)

(3.7)


81/230

MinthigianTrtricci

TrtriccitiX dB l trthigian m nnglnganggimX dBso vinnglngcci

Thigian nhtqun, Tc

L thigian knh tngquan rtmnhvitn hiuthuT

cxc nh tnh tnhcaknh, cc k hiu truyn qua knh chunhhngca

phadinh nhnhau (knh phadinh chm)


82/230

Quan hcc thng strong cc minkhc nhauBngthng nhtqun v tritrtrung bnh qunphng

Bngthng nhtqun l ditnm knh c ctnh tnhtheo tns, tc ngcaknh ln cc thnhphnphtrong ditnunhnhau

Vitngquan tnsl 0,5

Thigian nhtqun v tridoppler

c

1B

5t

=s

(3.8)

C

d

Tf

1

(3.9)


83/230

in khng gian in tn s in thi gianThng s d;

Thngging ngunhin

fd; ;

Nhcim Chnlckhng gian Chnlctns ChnlcthigianGiiphp MIMO OFDM Thch ng

Mcch Lidngang Phainhphng

(T)

Phainhchm

(BS>>fd)

Ch thch d: khong cch thu pht; MIMO: Multile Input Multiple Output; fd:

triDoppler; BC: rngbngnhtqun caknh xt cho trng

hp tngquan lnhn90%; T: chu kk hiu; : tritrtrungbnh qun phng; TC: thigian nhtqun caknh; BS: rng

bngtn hiupht

Tngktctnh knh

cB

1

50c

d

Tf

1

Bng3.1 Cc ctnh knh caba min


84/230

Phn loiphadinhphmvi hp

TritrangL thng sminthigian, lm mo tn hiudo trv phadinh chnlctns(nhhngln ctnh knh mintns)

Phadinhphng

Phadinh chnlctns

TridopplerL thng smintns, dnntn tnv phadinh chnlcthigian (nhhngln ctnh knh minthigian)

Phadinh chm

Phadinh nhanh

nghaiu kin phadinh ngoi ph thuc thng s knh l tri tr a ng v bngthng nhtqun, cnphthuccimcatn hiubao gmchu kk hiuvrngbngtn

Lachntn hiuph hpscithinchiunngtruyndn


85/230

Phn loiphadinhphmvi hp

B: rngbngtntn hiu

Bc: Bngthng nhtqunf

d: Tridoppler cci

T: Chu kk hiu

: Tritrtrung bnh qunphng

Csphn loi Loi Phainh iu kin

TritrangPhainhphng B


86/230


87/230

Phnbphadinh RayleighGi trtrung bnh caphnbrayleigh

Phngsai caphnbrayleigh (thnhphncng sutxoay chiu)

(3.11)[ ] ( ) ,tb E rp r dr

0

21253

[ ] - [ ] ( ) ,r E E r p r dr

2

2

2 2 2 2

0

222 2

0 4292 (3.12)


88/230

Phnbphadinh Rice

L phn bngbao phadinh phmvi hp, nhnckhi tn hiu thu cthnhphnnnhvttri, (LoSLine of Sight)

Thnhphnangxpchngln tn hiuvttri

Hm mtxc xut

A: Bin nhcatn hiuvttri

I0(.): Hm Bessel citinloimtbckhng

(3.13)

( )

cos

, ,( )

,

( )

r A

y t

A rr Ar

e If r

r

I y e dt

2

2 2

202 2

0

0 0

0 0

1

2


89/230


90/230

M hnh knh trong minthigian

Nguyn tc:Knh phadinh ang: ctrngton hcbngblctuyntnh thay itheothigian (ngtr)

Knh ctrngbngpngxung kim knh

Tn hiuurabngtch chptn hiuuvo knh vipngxung kim knh

( )

( ; ) , , ....,( ) ( ) ,

Li t

h t Lt e t

1

00 1 1

$(3.15)

Trong

l (t), l (t), l (t) biu th cho bin , pha v tr i vi xung thu th l (ng truyn l);

biu th cho tr, t biu th cho s thay i theo thi gianca chnh cu trc xung kim(.) biu th cho hm Delta Dirac, L biu th cho s ng truyn

( ) ( ) ( , ) ( ) ( , )y t x h t d x t h t


91/230

M hnh knh trong minthigian

D t D t D t

0Q

x(t)

0b

1b

L 2-b L 1

b-

y(t)

0 0t = t l1t = D tL 2 (L 2)-t = - D t L 1 ( L 1)-t = - D t

1Q

L 2-Q

L 1-Q

Hnh 3.6 M hnh knh v tuyndi ngbngngtranhnh


92/230

M hnh knh trong mintnsNguyn tc:

S thay i thigian trdnn thay i tns f,ngha l tn thicaknhkhinknh mang tnh chnlctns

Thchinbinifourier pngxung kim knh trong minthigian

(3.16)'

-[ ' ( )]

( ', ) ( , ) ( , )j f

Lj f t

h f t h t e d h t e

21

2

0


93/230


94/230

Phn tpkhng gian

Sdnghai anten trln cho thu hocpht

Btr cch nhau > 5theophngthngng

Khongcch mbotn hiuitrn hai knh khng tngquan nhau

ngthicng truynmttn hiutrn hai knh

Do hai knh clpnn khngbphadinh ngthiKthptn hiutcc anten nhnctn hiutt

L phngphp sdngphbin, chngccphadinh phngv phadinh lachn, thngsdngphn tpkhng gian thu

f

f

Tx

Rx

Rx

KthpSliuvoSliura

Hnh 3.7 Phn tpkhng gian


95/230

Phn tptns

Sdnghai cpmy thu/pht lm vichai tnskhc nhau

Cc tnsphic khongcch mbokhng tngquan phadinh vinhau

Tonn hai knh v tuynclp

ngthicng truynmttn hiutrn hai knh

Do hai knh clpnn khngbphadinh ngthiKthptn hiutcc my thunhnctn hiutt

Lphngphp sdngkhng hiuqutns,phctptrong cuhnh, hiuqutrong chngphadinh lachn

Hnh 3.8 Phn tptns

SW

f2

f1

Tx1 Rx1

Rx2

Sliuvo Sliura

Tx2


96/230

Phn tpthigianPhadinh su xyra trong thigian ngngy licm

Phn tn thigian tn hiupht khcphclicm

Phn tn cc litrong khongthigian rnghn

Duy tr chtlngtuyndntrung bnh gi trmboyu cu

Thchinbngkthutanxen tn hiutrckhi pht

Lphngphp hiuqutrong vicchnglikhi, csdngphbin

Hnh 3.9 Phn tpthigian


97/230


98/230


99/230

Nidung chng4: (5)4.1 Giithiu

4.2 Cc tham scbncaanten

4.3 Cc ngunbcxa nguyn t4.4Cu hiv bi tp


100/230

Vai tr caanten

L thitbbc x sng in t ra khng gian v thu nhn sng in t tkhng gian bn ngoi

Anten pht: Binitn hiuincao tntmy pht thnh sng inttdo lantruyntrong khng gian

Anten thu: Tptrung nnglngsng inttrong khng gian thnh tn hiuin

cao tnanmy thu.


101/230


102/230

Qu trnh vtlbcxsng int

intrngxoyL intrngc cc ngsckhngbrngbucvicc intch tora n mtbnthn chng khp kn.

iukintosng int

Quy lutcain t trngbin thin, in trngxoy bin thin ssinh ra t

trngbini. Bnthn ttrngbinilisinh ra mtintrngxoy mi.Qu trnh lpliv sng intchnh thnh

Hnh 4.3. Qu trnh truynlan

sng int


103/230


104/230

Hm tnh hng

Khi nim: L hm sbiuthsphthuccacngtrngbcxbianten theo hngkhost khi cly khost l khng i

, : Gcbcxcaanten (gcphngvv gc ngng)

Hm tnh hngbin : Biu thquan hcabin trngbcx theo

hngkhost vicly khost khng i

Hm bin tngi(chunha)

, , . , .f f i f i (4.1)

22

, , ,f f f (4.2)

ax

ax

,, ; 1

, m

m

fF F

f

(4.3)


105/230

thtnh hng

L thkhng gianbiuthsbinitngicabin trngbcxtheohngkhost khi cly khost l khng i

cvtF(,) trn tacchoctacc

Mtphngchnvthl hai mtphngvung gc iqua hngbcxccicaanten

Vi tacc, trcchun ban uchn trng vi trcixngca th, btuhngcci

Thangbiudinc ththeo thang thpphn hay thang logarit

-60 -30 30

o

0,25

0,50

0,75

1,0

0 90-90 60

Hnh 4.5. th

tnh hng


106/230

rngthtnh hng

L gc giahai hngm theo hngcng sutbcxgimGcbcxkhng (2

0): Cng sutbcxhngccigimn0

Gcbcxnacng sut(21/2

hay 3dB

): Cng sutbcxgimmtnaso vihngcci

Thhintnh tpchung nnglngbcxtheo hnglm vic

0180

00

090

2/maxP

2/maxP

maxP

)(2 32

1 dB

02

0

0

Hnh 4.6. rngca

thtnh hng


107/230

Cng sutbcx, intrbcx, hiusutCng sutbcx(P

): Lphncng sutbcxthnh nnglngint

Cng sut tnhao (Pth

): Cng sutb tiu tn do nhitbivtdn, trong cc lpinmi

Cng sutavo anten: Pa= P

+ P

th

Hiusutanten

intrbcx:

*intrbcxctrngcho khnngbcxcaanten

1

1a

tha

P

PPP

21 .2

mP I R

(4.4)

(4.5)


108/230

Hstnh hng, hstngchHstnh hng

L tsgiamtcng sutcaanten timthngxc nhvimtcngsut ca mt anten chun khi hai anten t cng v tr v cng sutbc x nhnhau. Anten chunthngchnanten v hng

Hskhuychicaanten (tngch)nhnghanhhstnh hngnhnghai anten c cng sutavo anten nhnhau v anten chunc hiusutbng1

Hstngch vabiuhintnh hng, vabiuthtnhao trn anten

2

2

0 0

2

ax ax

, ,, ; , ;

, . , , . ,m m

S ED D

S EE E F D D F

0

,, . . ,a a

SG D

S

(4.6)

(4.7)

(4.8)


109/230

thphng hng ca anten omni-directional v anten c hng


110/230

Trkhng vo

Anten l ticamy pht, trstictrngbitrkhng vo caanten

ThuntrR ctrngcho thnh phnnnglngbcxthnh sng int

inkhng X l do phntrnggn, brng bucvianten (v cng)

Trkhng vo nhhngtichlm viccacc thitbnitianten

ava va va

a

UZ R jX

I

Hnh 4.7. Mch trkhng tng ng ca anten

(4.9)


111/230


112/230

Chntin(dipol in)Khost trngtiimM

Tntivecto intrngtrong mtphngintrng()

Tntivecto ttrngtrong mtphngttrng()

sin ( / )4

0

0

sin4

ikre

ikre

ikZ eE I l i V mr

E

H

ik eH I l i

r

(4.10)


113/230

Chntin(dipol in)Khost trngtiimM

Tntivecto intrngtrong mtphngintrng()

Tntivecto ttrngtrong mtphngttrng()

sin ( / )4

0

0

sin4

ikre

ikre

ikZ eE I l i V mr

E

H

ik eH I l i

r

(4.10)


114/230


115/230

Chntin(dipol in)

Khost trngtiimM

Cng sutbcx

intrbcx

Hstnh hng

222

2 3

0 0 0

1 1E x H . sin sin

2 2 4

e

e

s

Z I lEP ds d r d d

Z

22

3

e Z lR

22

3

e

e Z I l

P

2 2 2

ax

, .4 .1 3, . sin

2 . 2

3/ 2

h

m

E rD

Z P

D

(4.13)

(4.14)

(4.15)


116/230

Chntt(dipol t)L phntdntthng, rtmnh, c di l rtnhhnbcsng.Dng tphn bucvbin v pha

Hnh 4.12. Bc xca chn tttrong khng gian tdo

Hnh 4.11. Phn bdng ttrong chn t

Im

l

E

H

Ima)

H

EIm

x

z

Im

r

k

E

H

y


117/230


118/230

Chntt(dipol t)

Khost trngtiimMNhnxt

Trngbcxcadipol tl trngphn ccngthng, intrngchc thnhphnE

v ttrngchc thnh phnH

MtphngH trng vimtphngkinh tuynchatrcchnt, mtphngE trng vimtphngvtuynvung vitrcchnt

Hm tnh hng

Trngbcxc hngtrong mtphngH, v hngtrong mtphngE

, . .sin .

, . . sin

sin onst

onst onst

m

m

f I l i

f I l

F c

F c c

(4.17)

(4.18)


119/230

Chntt(dipol t)

Khost trngtiimMthtnh hng

c) Ta vung gc

1,00,80,60,40,2

1,00,80,60,40,2

360000 1800360000 1800

00

F()F()

a) Trong khng gian

x

y

z

b) Ta cc

E

F(); = const

F() = 1;= const

Hnh 4.13. thtnhhng ca dipol t


120/230


121/230

Nguyn tbcxhnhp

Trngbcx

Hm tnh hng

Hm tnh hngchunha

M(,)

Iex

x

z

Imyr

y

Hnh 4.14. Nguyn t bc xhn hp

os os +a4

sin 1 os4

ikre

x

ikre

x

ikZ eE I lc c i

r

ikZ eE I l ac i

r

, os os +a

, sin 1 os

e

x

e

x

f ZI lc c i

f ZI l ac i

os os +a,

1

sin 1 os,

1

c cF

a

acF

a

z

y

x

z


122/230


123/230

CHNG 5

NI DUNG


124/230

Nidung chng5: (9)5.1 Giithiu

5.2 Bcxcachntixngtrong khng gian tdo

5.3 Cc tham scachntixng

5.4nhhngcamttln bcxcachntixng

5.5 Hhai chntixngtgnnhau

5.6 Cpincho chntixng

5.7 Cu hiv bi tp


125/230

5.1 Giithiu


126/230

Phn bdng in

Tngquan chntixngv ngdy song hnh

Khc bit

Thng sphn bL, C thay idctheo chnt

Nnglngbcxra khng gian didngsng int

Vichntmnh(d > ): Coi l tng

quan. Phn bdng intrn chntixngc dngsng ng

Phn bintch

.sinz bI z I k l z

Ibl bin dng in im bng .

l: l di mt nhnh chn t

..cos . , 0

.

..cos . , 0

.

b

z

b

k Ik l z z

iQ

k Ik l z z

i

(5.1)

(5.2)


127/230

5.2 Bcxcachntixngtrongkhng gian tdo


128/230

Bi ton

Chntixngchiudi 2l ttrong khng gian tdo

Khost trngtiM cch chntr0>> , lpvitrcchntgc

Xc nhcngtrng

Chia chntthnh cc phntrtnhdz


129/230

5.2 Bcxcachntixngtrongkhn

g gian tdo


130/230

Xc nhcngtrng

intrngdo ton bchntgy ra tiM

g g

0 0

0 00

0

cos klcos coskl60 60. . . . . ,

sin60.

. ,

l

ikr ikr b b

b

I IE d E i e i i e f

r rI

E fr

(5.7)

(5.6)

5.3 Tham scachntixng


131/230

Hm tnh hngv thtnh hng

Hm tnh hngbin

Trong mtphngH vung gc vitrcchntc l hngs, hm tnhhngchphthucvo k.l, (hay chiudi tngil/)

Chntngn: l < /4

Tngtchntin: C hng mtphngE chatrcchnt, v hngmtphngH vung gc vitrcchnt, cci hngvung vitrc

cos klcos cos kl

,sin

f f

22 k.lxcosx 1 sin

2 2

sin

x f

F

(5.10)

(5.9)

(5.8)


132/230



133/230

Hm tnh hngv thtnh hngHm tnh hngbin

Chntdi: l > /2

Trn minhnh xuthindng inngcpha, do

Ti hng vung gc, khng c sai pha v ng i nhng dng in

ngcpha nn cngtrngtnggim(bp chnh thu hpli)Tihngc sai pha vngi th sai pha cb trnhsai pha vdng innn xuthincc bp ph(bp ph lndn). Khi l = , bnbpphtrthnh bnbp chnh.

Tnh hngcachntixngphthucvo chiudi inl


134/230


135/230



136/230

Trkhng sng, trkhng voTrkhng vo

Vingdy song hnh hmchucuic trkhng vo

Chntixngnnglngbcxra khng gian nn c thnh phnintrbcxuvo ngvai tr thuntr

Trkhng vo cachnt

(Vil < 0,75)

cotg .vA AX iZ k l

2

2

sin

.cotgsin

bvA

bvA vA vA A

RRkl

R

Z R jX iZ kllk

(5.17)

(5.18)

(5.16)



137/230

Trkhng sng, trkhng vo

Trkhng vo

- 300

- 400

- 200- 100

0

100

200

300

400

0 0,2 0,4 0,6 0,8 1,0 1,2

XVA()

l/r=40

l/r=20

l/r=60

100

-100

200300

400

500

600

700

800

0 0,2 0,4 0,6 0,7 1,0 1,2

RVA()

l/r =40

l/r =20

l/r =60

0

Hnh 5.5. Sphthuc ca ZvA vol

Nhn xt:-Chn t ngn (l < /4): cotg l (+) nn ZVA l (-) Tr khng vo mang tnh dung-Chn t na sng (l = /4): cotg = 0 nn ZVA = RVA= 73,1 Mch cng hng ni tip-Chn t c (/4 < l < /2): cotg l (-) nn ZVA l (+) Tr khng vo mang tnh cm-Chn t ton sng (l = /2): cotg = 0, sin = 0, nn ZVA= Mch cng hng songsong

C



138/230

Cng sutbcx, intrbcx, hstnh hngCng sutbcx

Cng sutbcxqua dintch ds

Cng sutbcxcachnt

x

d

ds = r2sindd

z

r

y

2

22 2

2

2 2

0 0

2

2

0

. . .2

cos klcos cos klsin

8 sin

cos klcos cos kl30 .

sin

b

b

tb h h

EdP S ds E H ds

Z

ZIP r d d

r

P I d

(5.20)

(5.19)



139/230

Cng sutbcx, intrbcx, hstnh hng

intr

bc

x

Xc nhtiimbng

Nhnxt

Khi l/nh, gingdipol in, tngl lm cho dng ngpha tngTngRKhi l > /2, xuthindng inngcphaGimR

intrbcxdao ngcci di l bischnln/4, cctiudi l bislln/4

2

2

0

1.

2

cos klcos cos kl60 .

sin

b b

b

P I R

R d

(5.21) 0

50

100

150

200

250

0,25 0,5 0,75 1,0

Rbxb

()


140/230

Chi di hi d



141/230

Chiudi hiudngKN: L chiudi tngngcamtchntc dng inphn bnguv bngdng inuvo cachntthtvidintch phn bdngintngng.

ImIm

2l = /2 lhd

Hnh 5.8. Chiu di thc v chiu di hiu dng cachn ti xng

..2

hdk ll tg

Nhn xt:

-Chn t ngn: Coi tgx = x lhd = l (chiu di mt nhnh chn t tht)

-Chn t na sng: tg = 1 lhd= /

(5.23)

Ph h h

5.4 nhhngcamttln bcxcachntixng


142/230

Phngphp nhgngChnttrong mi trngthc, cc vtdn gnnhhngtisbc

x

nhhngcamttcxc nhbngphngphp nhgng

Tc dngcadng thcpxc nhtngngvimtchntol nhcachntthtqua mtphn cch giahai mi trngchntnh

Bc xstng ng vi hhai chn tc khong cch 2h t trong khng gian t

doTheo l thuyt phn xsng phng, quan hdng: Ia= It.R.ei

Ie

h

h

EtEt

E0 E0

Im

h

h

EtEt

EE

Ie

EtEt

EE

Hnh 5.9. Nguyn lnh gng

B h t i t



143/230

Bcxcachntixngtnmngang

r0

M

r1

h

h r2

Hnh 5.10. Chn ti xng tnm ngang trn mt t

-Coi l hai chn t i xngc dng in ngcpha

-Xc nh cng trng ti M cch xa chn t

1 0 0

0

2 . .sin

2 1

2 . .sin

1 2 0 0

2

0 0

.

cos kl.sin cos kl

1-cos kl .cos

. 1

. 1 2 cos 2 . .sin

px

px

i k h

px

i k h

px

px px px

E E F

F

E E R e

E E E E F R e

E E F R R k h

E0: cng trng ca chn t hng bc x cc iF0(): hm tnh hng chun ha ca chn t trong mt phng kho stE1: bin cng trng ca chn t i xng trong khng gian t do

: hng kho st

(5.24)

(5.25)

(5.26)



144/230

Bcxcachntixngtnmngang

Chn t t nm ngang nn mt phng vung gc vi trc v i qua tmchn t c F0() = 1

Vi mt t dn in l tng c R = 1 v =

F() thhinnhhngcamttthng qua chntnh

0 02 1 cos -2k.h.sin 2 .

sin . .sin

E E E F

F k h

90o

= 0o180o

h = 0,25 ; =

180o

90o

= 0o

h = 0,5 ; =

Hnh 5.11. thtnh hng ca chn ti xng t nm ngang trn mt t (mp H)

(5.28)

(5.27)



145/230

Bcxcachntixngtthngng

Hai chntc dng inngpha

Hm tnh hngbin gingcachntixng(v l gc phnhau)

Hnh 5.12. thtnh hng ca chn ti xng t thng ng trn mt t (mp H)

0 0

0

os klsin osklos sin

1-coskl os

2 .

c cF F c kh F

c

E E F

90o

= 0o180o

l= 0,25; h = ; =

90o

= 0o180o

l= 0,25; h = 0,75; =

(5.30)

(5.29)

Bc x ca h hai chn t t gn nhau



146/230

Bcxcahhai chnttgnnhautoanten c tnh hngkhc nhau phisdnghchntixng

tgnnhau

Quan hdng trong hai chnt

222

1

iI a eI

a2- l tsbin dng in ca chn t2 v chn t12- gc sai pha ca dng in trong chn t2 so vi dng trong chn t1

E

M

2l

d

z

a) Mt phng E

M

H

b) Mt phng H

z

d

Hnh 5.13. Hhai chn ti xng t song song gn nhau

(5.31)

B h h i h t t h



147/230

Bcxcahhai chnttgnnhauCngtrngtiimkhost

Hm tnh hngtnghp

Hm ny phthuccc gi trkhc nhau cad/v a2.e-i2

2

2

1 2

cos

1 2

os

2

. . . 14

1

M

ikri ikd

i ikdc

k

E E E

ik eE f a e e

r

f a e e

(5.33)

(5.32)


148/230


149/230

Bc x ca h hai chn t t gn nhau



150/230

Bcxcahhai chnttgnnhau

d/= 1/4

a) = 0o

90o

0o

180o

d/= 1/2

d/= 1

b)= 180o c) = 90o

Hnh 5.14. thphnghng ca hai chn ttsong song vi nhau

Tr khng vo in tr bc x ca h hai chn t



151/230

Trkhng vo, intrbcxcahhai chnt

Trkhng vo

Stngnghhai chnt

Trkhng vo camichntgmthnh phntrkhng ring v trkhng tnghcachntln cn

e2

Z11 Z22

Ia2Ia1

aei.Z12 (1/a).e-i.Z12

Hnh 5.15. Stng ng hhai chn t


152/230

Tr khng vo in tr bc x ca h hai chn t



153/230

Trkhng vo, intrbcxcahhai chnt

*intrbcx

intrbcxcahkhng phthucvo inkhng ring v inkhngtnghcahai chnt

2

*

1 11 11 12 12

*

2 22 22 12 12

*21 1

1 2 11 22 12

2

0 11 22 12

.

2

os sin2

1 cos sin2

2aR cos2

2aR cos

bxbx

a abx

a abx

a abx bx bx

bx

I RP

I IP R a R c X

I IP R R Xa

I IP P P R a R

R R a R

(5.41)

(5.42)

(5.43)

(5.44)

Chn t ch ng chn t th ng



154/230

Chntchng, chntthngChntchng:cnitrctipvingunv tbcxsng int

Chntthng: Khng ccpngun, hotngdatrn nguyn tccmngintNgunbcxthcp

e1

Ia2

X2c

Ia1

d

a) Z11 Z22

Ia1

aei.Z12 (1/).e-i.Z12

X2c

b)

Hnh 5.16. a) Chn tghp; b) Stng ng

2

1

. ia

a

Ia e

I

(5.45)

Chn t ch ng chn t th ng



155/230

Chntchng, chntthngDng trong chntthng

Trkhng vo v intrbcx

1 1 11 2 12

2 12 12 122 22 2dc 2 21

1 22 2 22 22 2

2 2

12 12

2

222 22 2

22 212

12 22

i.X0 iX

iX R X

XXarctg arctg

R

a a

aa a

a dc dc

dc

dc

e I Z I Z

I Z RI Z I Z

I Z i X

R Xa

R X X

X

R

2

121 11 1 2

22 2

2

0 11 22 12

; 0 0

. 2 . .cos

v v

dc

bx

ZZ Z Z eZ iX

R R a R a R

(5.46)

(5.47)

(5.48)

(5.49)



156/230

Cpinbngdy song hnh

ChntkiuY

ChntkiuT

l2 l1l1 l2

2l = /2

DC

d

DA /4

C

A

22AA AA

sin

73,1v

klR R Z

Hnh 5.19. Tip in kiu song song v mch tng ng

O

A /4

C

A

O

l2 l1l1 l2

2l = /2

DC d1

d2

O OA

A

Hnh 5.20. Tip in kiu song song kiu T v mch tng ng



157/230

Cpinbngdy song hnhChntvng dt

/2

A A

+_

CA A

C

Hnh 5.21. Chn tvng dt v mch tng ng

' 4 292bx bxR R



158/230

Cpinbngcp ngtrc

I1

I2

I2 I1

I2

I2

(a)

ab

O

(b)

a

b

O

Hnh 5.23. Cp in trc tip Hnh 5.24. Cp in c bphi hp



159/230

Thitbbiniixngdng oncp chU

I

l1I1

I2

I2 I1

oa b

d c

(a)

l2= l1+/2

oa b

/2

Hnh 5.25. B bin i i xng ch U


160/230

CHNG 6


161/230

CHNG 6

NI DUNG


162/230


6.2 Anten nhiuchnt

6.3 Anten loa

6.4 Anten gng

6.5. Anten vng

6.6. Anten xon

6.7 Cu hiv bi tp


163/230


164/230


165/230

6.2 Anten nhiuchnt


166/230

Dn chntngpha (2)

-

-

-

-

+

+

+

+

-

-

-

-

+

+

+

+

/2

/2

a)b)

Dn chn t ng pha (3)

6.2 Anten nhiuchnt


167/230

Dn chntngpha (3)

cimlm victhtnh hnggingchntixngnhngc tnh hngcao hn.

Hngbcxcciti= 0 v

bcxnhng: Kthpvimtphnx, khongcch d =(0,20,25)

= 0o180o


168/230


169/230

Anten Logarit ch k

6.2 Anten nhiuchnt


170/230

Anten Logarit chu k

CutoNhiuchntc di khc nhau, t khongcch khc nhau

Kch thcv khongcch anten thay itheo mttlgil chu kanten

tsong song vinhau trn mtmtphng

Tipincho ttccc chnt

Tipinngpha

1 11 2 1 2

2 3 2 3

.. ...n n

n n

d ld d l l

d d d l l l

Anten Logarit chu k (2)

6.2 Anten nhiu

chnt


171/230

Anten Logarit chu k(2)

max= 0,95

min= 100

l6l5l4l3l2l1Phi cpin

d1

d2

d5

Anten Logarit chu k(3)

6.2

Anten

nhiu

chn

t


172/230

Nguyn l hotng

Tnskch thch l f0: Chntl

0=

0/2 ngvai tr chntchng(tr

khng vo thuntr= 73,1)

Cc chntkhc c thnh phninkhng, gi trphthucdi so vichntcnghng

Tipinso le, cc chntpha trc(l < l0

) thomn iukincachnthngx, cc chntpha sau (l > l

0) thomn iukinchntphn

x.

Minbcxcaanten chyutobichntcnghngv mtvichntln cn.

Cng thcxc nhtnslm vic

ln.1ln

.

1

1

1

nf

f

ff

n

n

n

6.3

Anten khe

Anten khe nasng

C t


173/230

Cuto

Nguyn l hotngDi tc dng ca sc in ng t vo khe, trong khe s xut hincc ng sc in trng hng vung gc vi hai mp khe

phn b ca in trng dc theo khe cng tun theo quy lut sngng

khe tng ng nh mt dy dn t

Trng bc x ca anten khe

Ee

x

ze

/2

y

Hnh 6.7. Anten khe na sng

2 sin2

m

day bkhe

lI U z

kl klos os os

2 2sin

kl klos os os

2 2

sin

ikrbkhe

ikrbkhe

c c cUE i e

r

c c cU

H i eZ r

6.3

Anten khe

Kh os os

2c c

U


174/230

Khe c

th phng hng ca khe na sng

0

0

2

sin

os os2

sin

ikrkhe

ikrkhe

UE i e

r

c cU

H i eZ r

2l

z

x

a)

y

x

b)

Hnh 6.8. thphng hng ca khe na snga) trong mt phng H b) trong mt phng E


175/230


176/230


177/230

6.4 Anten gng


178/230

Nguyn l

Datrn nguyn l lm viccagngquang hc

Bbcxscp: Bcxra sng intvimtsng v hngtruynlan xc nh.

Mtphnx: Binithnh sng thcpvimtsng v hng truynlan theo yu cu nh kt cu ca mt phn x lm vic theo nguyn lgngquang hc.

Anten gngthngc tnh hngcao

Sng thcpl sng phng, tpchung nnglngtrong mtkhng gianhp.

Anten Parabol

6.4

Anten

gng


179/230

Cuto

Bbcxscp: Sdnganten chntixnghocanten loa. Vtrttitiu imparabol.

Mtphnx: Hnh parabol trn xoay vihsphnxcao.

Anten Parabol (2)

6.4 Anten gng


180/230

Nguyn l hotng

Tnh chtquan hcgngparabol

FO + OO = FA + AB = f + h = Const.

Cc tia sau khi phnxinminggngviqung ngnhnhau,do timinggngmtsng l mtphng.

A

O

B

F

0

0

FO

A

f

a) b)

Oh

dz

Anten Parabol (3)

6.4 Anten gng


181/230

Cc tham s

thtnh hng

0 dB

3 dBBp chnh

Cc bp ph

Bp

ngc

G

1800- 18000

21/2

3 12

212dB

fd 3 1

2

702

dBd

Anten Parabol (4)

6.4 Anten gng


182/230

Cc tham sHstnh hng, hskhuychi

2

2

4 S dD

2

2

4 S dG

4,20lg20lg20dBiD GHzm fd

( ) 20lg 20lg 10lg 20,4m GHz G dBi d f

Mtsloianten gng

Anten Cassegrain (anten hai gng)

6.4 Anten gng


183/230

Anten Cassegrain (anten hai gng)

FF2 1

Gng phn xchnh

(Parabol trn xoay)

Gng phn x ph

(Hybperbol trn xoay)

Mtsloianten gng

6.4 Anten gng


184/230

Anten Gregorial


185/230

Anten vng l loi anten m phn t bc x c bn ca nl cc vng dy dn c dng in sng ng. Cc vng dy


186/230

l cc vng dy dn c dng in sng ng. Cc vng dy

dn ny c hnh dng khc nhau (trn, vung, tam gic),c hoc khng c li t tnh, v c qun theo nhiu cchkhc nhau.

Anten khung nh Anten khung ln Anten t,

Ty theo kch thc v kt cu cth

m anten c tn gi ring:


187/230

2 230 sin

ikRe

v

eE I k a

R


188/230

Cc i theo phng nm trongmt phng vng dy

Bng khng theo phng vunggc vi mt phng vng dy

in tr bc x ca vng dy c gi tr rt nh

2

4 2320 /R S

Hm phng hng

ca trng bc x

dE


189/230

dlTrong :

sinHS l t thng xuyn qua vng dyS l din tch vng dy

H l gi tr tc thi ca cng t trng

l t thm hiu dng ca mi trng

sine j SH


190/230

0

0

sinW

he i S E

Vi

0WEH

'

0h

'0h kW

2k

' sinhe i kS E

Trng hp anten gm n vng dy

' sinhe i nkS E


191/230

i vi khng kh hoc cc vt liu in mi khc c th


192/230

i vi khng kh hoc cc vt liu in mi khc c th

coi gn ng :'

1h

Sut in ng cm ng v di hiu dng

axm

hd

e nkSE L nkS

Thng vng dy c mc vi t iuchun C to thnh mt mch cng hng

ax axm mU Qe knSQE


193/230

t thm hiu dng ca li l i lng ph thuc vo hnh dng,kch thc ca li, vo t thm tng i ca vt liu, v ph'


194/230

'

h A cm

Trong mAl h s ph thuc vo t s ca l/L, c xc nh gnng theo cng thc

1 0,3 /Am l L

'

'1 1c

N

N ph thuc vo kch thcv hnh dng ca li

thuc vo t s ca di cun dy vi di ton phn ca li L:

l t thm ca li, c xc nh theo cng thcc


195/230


196/230

Anten khung ln l anten khung m kch thc tng i


197/230

Anten khung ln l anten khung m kch thc tng i

ca n so vi bc sng khng nh hoc khng qu nh(kch thc khung c th so snh c vi bc sng)

Loi anten ny thng c s dng di sng cc ngn,mt phng anten c t song song vi mt t totrng phn cc ngang v bc x v hng trong mt

phng ngang


198/230


199/230

tng h s nh hng ca anten c th s dng nhiukhung t song song vi nhau theo phng thng ng

thc hin thc t cc anten khung ta cn ch rng khi di dy dnca khung c gi tr so snh c vi bc sng th phn b dng in trongkhung s tr nn khng ng u na


200/230

Khung c ch to t cc on

dy dn v chng c ni vinhau bng cc t in c indung c la chn mt cchthch hp

Anten khung c bin dng t

chn t vng dt, c mc t C hai u chn t. Tr khng vocu anten c gi tr khong 30 -40

Phng php nhn c phn b dng in u l phng phptip in ring l cho tng b phn ca khung

Khi y ngi ta chia khung ra thnh mt s on, v dng cc bin


201/230

Khi y ngi ta chia khung ra thnh mt s on, v dng cc bin

php thc hin vic tip in ng pha cho mi on y

di cc on phi c la chn th no va m bo in trbc x ca chng ln, va m bo phn b dng in tng i

u trn mi on


202/230

Anten xon l loi anten m phn t bc x c bn ca nl cc vng dy dn c dng in sng chy. Trng bc x


203/230

ca anten xon trong trng hp tng qut l trng phncc quay.

Xon tr Xon phng Xon hnh chp

Anten xon thng c ng dng trong

di sng cc ngn gm nhiu loi:


204/230

Gm mt ng dy xon dn in v mt mn chn kim loi

Anten c tip in bi mt fide ng trc, li ca fide c nivi ng dy xon, cn v fide ni vi mt kim loi

Cc thng s hnh hc c trng cho anten xon tr l bn knh a,bc sng s (hoc di l0ca mi vng xon v gc xon.), v svng N

Trn ng dy xon tr c th ng thi tn ti mt s dng sngdng in vi bin khc nhau v s chu k trn mt vng xon lkhc nhau


205/230

Dng sng c tc dng ch yu trong mi vng dy xon ph thucvo kch thc tng i ca vng xon so vi bc sng cng tc

Vi Tql cc dng sng (chs q = 0, 1, 2, 3biu th schu k sng trn mi vngdy),

Vi vql vn tc phaca cc sng tngng

Kho st 3 chlm vic ca anten xon trvi 3 loi kch thc anten sau

Dng sng ch yu trong ng dy xon tr l sng T0

Khi vng xon c di rt nh so vi bc sng cng tc) 0l


206/230

Sng T1v cc sng bc cao khc c bin rt nh v suy gimnhanh nn khng nh hng n ch bc x ca anten

Gin hng tnh

Khi tng kch thc xon ti mt gi tr nht nh th sng T0 s bin

mt v xut hin sng bc cao

Gi tr gii hn c xc nh bi h thc

minos

1 sin

cka

Trong thc t anten xon l vic ch bc xngang khi chiu di vng dy nh hn 0.65


207/230


208/230

Trong trng hp ny, bc sng T0v T1suy gim kh

Khi vng xon c di ln hn bc sng 0l


209/230

0 1

nhanh, dng sng ch yu trong anten s l cc sng bc caohn: T2, T3

Hng bc x cc i ca anten s lch khi hng bc x

xon

Thc t, ch bc x xin s xy ra khi di ca mi vng xon ln hn1,5

th phng hng

i vi vng xon, trng bcx trong trng hp tng qut gm


210/230

0 0

0 0

sin

sin os

f J ka

f J ka c

g g p g q g

2 thnh phn l vE E

Do hm phng hng cavng dy xon cng c 2 thnh

phn theo ta v

sin cos

2k

Nks

f


211/230

1sin cos

2

kf

ks

Trong

N- s phn t ca h ( s vng xon)

S- khong cch gia hai phn t (bc xon)

- Gc lch ca dng in hai vng k nhau

-Gc hp bi hng kho st v trc xon

Dng in hai vng dy k nhau cn c gc sai pha bng2

2s


212/230

Sai pha dng in gia hai vng dy ph thuc vo vn tcpha ca dng in truyn theo dy xon

0'

2l

l0- di ca mt vng xon

2

2

0 2l s a

-Bc sng trong dy dn ca ng dy xon'

01

l s


213/230

Nhc imca anten xon l hng tnh khng cao.

'

L h s chm ca sng truyn lan dc theo dy dn

u imca anten xon tr l kt cu n gin, di tnrng. H s bao trm gii sng ax min/ 1,7m

rng ca th phng hng tnh theo gc na cng sut


214/230

1/2

0

522o

sl N

rng ca th phng hng tnh theo gc bc x khng

1/2

0

1152

o

sl N

H s nh hng ca anten


215/230

2

015 l s

D N

in tr vo ca anten

0

140v

l

R


216/230

Anten xon phng acsimet

tip in cho anten xon phng logarit cng nh xon

Acsimet c th dng fide song hnh v kt cu ca cc antenny l kt cu i xng

Trong thc t, vic tip in cho anten c th thc hinbng fide ng trc. Khi y v ngoi ca fide c gn vomt nhnh ca anten xon, cn li ca fide ng trc ctip cho nhnh th hai

Anten xon phng lgarit


217/230

Cc nhnh ca anten c th c cu to t

cc l kim loi mng dn ln cc tm in mi

Anten c thit lp di dng cu trckhe xon

Anten xon phng acsimet Anten xon phng logarit

Phng trnh cc ng gii hn trong v gii hn ngoi


218/230

Phng trnh cc ng gii hn trong v gii hn ngoica cc bng xon

Bc sng cc i ca di tn s c quan h vi bn knhban u ca ng xon v c xc nh t h thc

0

0

' ' '' '

1 0 1

' ' '' '

2 0 2 0

;

;

aa

o

aa

e e

e e

Trong 0'

0

''

0

a pe K

p

ax1 1,5 ml


219/230


220/230

Anten xon logarit c hiu sut kh cao, vi nhng antenm di ca mt nhnh ln hn mt bc sng, hiu sutc th t ti 98%

Phng trnh ng cong


221/230

a b

Bc sng cc i v bc sng cc tiu ca anten

max ax

min min

2

2

mr

r


222/230


223/230


224/230

Anten xon chp cng c hai loi:

xon chp thng xon chp Logarit

H s bao trm gii sng ca anten ny c th t ti 20/1.


225/230

g g y

Thng thng gii hn trn ca gii tn cng tc i vi

anten xon chp s ng vi tn s m bc sng ca nbng di ca vng xon nh nht. Cn gii hn di sng vi tn s m bc sng ca n bng di cavng xon ln nht

min

axm

Tip y chp


226/230

Tip nh chpTip y chp

V nguynl tng t nh antenxon phng logarit nhng y cc


227/230

Phng trnh ca cc ng gii hn

0

' '

1 01

'' '

1 01

a

a

e

e

bng xon nm trn mt chp

Anten xon chp c th bcx n hng. Hng bc x ca

anten l hng trc, cc i vpha nh chp


228/230

Bi tpchng6

6.7

Cu

hi

v

bi

tp

1. Mt anten parabol ng knh 5m c hiu sut lm vic 0,65 lm vic ti tn s6GHz. Tm din tch mt mhiu

dng ca anten


229/230

dng ca anten

(a) 12,76 m2; (b) 13,76m

2; (c) 14,76m

2; (d) 15,75m

2

2. Sliu nh bi 1, tm hskhuch i ca anten.

a ) 45,1dBi; (b) 46,1dBi; (c) 47,1dBi; (d) 48,1dBi

3. Sliu nh bi 1, xc nh rng bp sng chnh.

a ) 0,50; (b) 0,7

0; (c) 1,5

0; (d) 1,7

0

4. Mt anten parabol ng knh 3m c hiu sut lm vic 0,55 lm vic ti tn s2GHz. Tm din tch mt mhiu

dng ca anten.

a ) 2,9 m2; (b) 3,5 m

2; (c) 3,9 m

2; (d) 4,5 m

2

5. Sliu nh bi 4, tm hskhuch ica anten.


6. Sliu nh bi 4, xc nh rng bp sng chnh.

a ) 2,50; (b) 3,0

0; (c) 3,5

0; (d) 3,7

0

7. Mt anten gng parabol c hskhuch i l 50 dBi, hiu sut lm vic 60%. Tnh gc na cng sut.a ) 0,44

0; (b) 0,54

0; (c) 0,64

0; (d) 0,74

0

8. Mt anten c gc na cng sut bng 20. Xc nh hskhuch i khi bit hiu sut lm vic ca anten l 55%.


Bi tpchng6

6.7 Cu

hi

v

bi

tp9. Mt anten pht c hskhuch il 40 dBi, anten c cng sut pht l bao nhiu anten thu gng parabol c

ng knh ming gng 0,9 m; hiu sut lm vic 0,55 t cch anten pht 50 km nhn c cng sut70 dBW.


230/230

g g g g , ; , p g

Githit sng truyn trong khng gian tdo.

a ) 0,5 mW; (b) 0,5 W; (c) 0,9 mW; (d) 0,9W

10.Anten gng parabol c hskhuch il 40 dBi, hiu sut lm vic 60%, lm vic ti tn s4GHz.Tnh ng

knh ming gng.

a ) 3,08 m; (b) 3,28 m; (c) 3,58 m; (d) 3,78 m

11.Skiu nh bi 10, tnh rng bp sng 3dB.

a ) 1,50

; (b) 1,70

; (c) 2,50

; (d) 2,70

12.Mt anten pht c hskhuch il 30 dBi, cng sut pht ca anten l 5W. c ly 50 km t mt anten thugng parabol c ng knh ming gng 1,5m. Tnh cng sut anten thu nhn c.

a ) 1,13 pW; (b) 1,13W; (c) 1,13 mW ; (d) 1,13 W

13.Sliu nh bi 12, tnh tn hao truyn sng trong khng gian tdo khi truyn tanten pht n anten thu.

) d (b) d ( ) d (d) d

Documents

Ly Thuyet Truong Anten Dh