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在通信、电视或其它无线电系统中,常使用水平天线 (Horizontal Antenna) 。水平架设天线的优点是: ( 1 )架设和馈电方便,阻抗可调; PowerPoint PPT Presentation


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第二章 简单的线天线. 2.1 水平对称天线. 在通信、电视或其它无线电系统中,常使用水平天线 (Horizontal Antenna) 。水平架设天线的优点是: ( 1 )架设和馈电方便,阻抗可调; ( 2 )地面电导率对水平天线方向性的影响较垂直天线的小; ( 3 )可减小干扰对接收的影响。因为水平对称天线辐射水平极化波,而工业干扰大多为垂直极化波,故可以减少干扰对接收的影响,这对短波通信是有实际意义的。. 天线的结构、结构参数、架设方法 天线的电参数,及其特点 天线的用途及尺寸选取方法 天线的优缺点 天线的改进方法. 第二章 简单的线天线.

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在通信、电视或其它无线电系统中,常使用水平天线 (Horizontal Antenna) 。水平架设天线的优点是: ( 1 )架设和馈电方便,阻抗可调;

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Horizontal antenna 1

2.1

(Horizontal Antenna)

1

2

3


Horizontal antenna 1

2.1

2.1.1

(Horizontal Symmetrical Dipole)36mm23m/4


Horizontal antenna 1

211

l=12m22m1000H=10m60044m2H+2l64m0.390300km


Horizontal antenna 1

z

P

q

H

A

O

D

y

j

x

1.

212

-1


Horizontal antenna 1

213213214

213


Horizontal antenna 1

213213214

214


Horizontal antenna 1

z

P

q

H

A

O

D

y

j

x

EH

l<0.7H212xOzrOPPzP


Horizontal antenna 1

1

212=0xOz=0213, fxOz(,=0)=|1-oskl||2sin(kHsin)| (214)

xOz1174


Horizontal antenna 1

1

fxOz(,=0)=|1-coskl||2sin(kHsin)| (214)

(1)H/l/H/

(2)H/=0

(3)H/0.25H/0.3=90=60900300km


Horizontal antenna 1

(4)H/>0.3H/m1m1172

m100H

0

(5),


Horizontal antenna 1

2 213:

f1()215216l/=0.25l/=0.50


Horizontal antenna 1

215216l/=0.25l/=0.50

215 l/=0.25

216 l/=0.5


Horizontal antenna 1

(1) H/

(2)l/,l/,l/<0.7=0l/>0.7=0,l/0.7

(3)cossin

216 l/=0.5

215 l/=0.25


Horizontal antenna 1

(1)

(2)H/0.3,,0300km

(3)

(4)=0l/0.7


Horizontal antenna 1

2.

,217

217 l=20mH=6m


Horizontal antenna 1

3.

,f(m1,)m1 2 15;Rr

f(m1,)RrRr=R11-R12R11R122H218H>/2l/H

218 D~l/


Horizontal antenna 1

4.

1) l

(1)

l<0.7minmin(=0)


Horizontal antenna 1

(2)

l/Al/0.1219l0.2

l0.2max (2110)

219 K~l/

0.2maxl0.7min (2111)

,230MHz210MHz,2l=222m1030MHz2l=212m


Horizontal antenna 1

2) H

300km,H=(0.10.3)815m

m10

216H

r<1000km310MHz0=47.510MHzH=10m3MHz0.1=90=47.50.760


Horizontal antenna 1

2.1.2

64m210222=64m4mm1k350

1.75ma


Horizontal antenna 1

(Cage Antenna)21106835mm13m250400

2110


Horizontal antenna 1

34m

ae:

abna2mmb1.5mn8ae0.85m64m353.6


Horizontal antenna 1

2111a2111b354637434(2111(a))

2111

(a)(b)


Horizontal antenna 1

211221132114

2112

2114

2113


Horizontal antenna 1

2.1.3 V20

1l/=0.635Dmax=3.296

l=90202115V(Vee Dipole)

1

2

V1.4

,Im;l;r;


Horizontal antenna 1

V

1

2

V=0V

,V2116

2116 V


Horizontal antenna 1

l/202optl/2opt0.5l/3.0V,

2opt

2116 V

V20VV


Horizontal antenna 1

0.5V

3V

2l,

1

2

3

4LPDA


Horizontal antenna 1

2.1.4

1.


Horizontal antenna 1

2.

(1):,

(2)

(3)


Horizontal antenna 1

1.

112VHF48.5~223MHz1368UHF470958MHz


Horizontal antenna 1

888()


Horizontal antenna 1

2.

(Turnstile Antenna)

211790


Horizontal antenna 1

A2119kr E=E1+E2=Asin(t+-kr) (2120)

2120kr2120t=08E882118a

2118


Horizontal antenna 1

5%2118b

2118

8


Horizontal antenna 1

3. VHF(Batty Wing Antenna)2119EE2120

EE

2119


Horizontal antenna 1

AEEDCBADA150/2


Horizontal antenna 1

2121

11.12025%

2

3

2121


Horizontal antenna 1

75


Horizontal antenna 1

2.2

H/,(Vertical Antenna)221(Monopole Antenna)

221


Horizontal antenna 1

H(HH)

1

2Q

3Pin=RinI2in/2Uin=Iin(Rin+jXin)jIinXin

f/f02f


Horizontal antenna 1

2.2.1

(Whip Antenna)221222

1.

1

2

1.72H/<0.13

222

(a)(b)


Horizontal antenna 1

3

1.2.8

He

223

,I0;H

223

H/<0.1


Horizontal antenna 1

H<<( )223He=H/2He

4

224Rin=Rr0+Rl0 (224)

Rr0Rl0:

A72

224


Horizontal antenna 1

5:H1%

5.1.

225(TopLoading)226

225

226


Horizontal antenna 1

H226(a)226(b)CaZ0H:

226

,H;ah0=h+h

1/5~3/10h(0.1~0.2)h


Horizontal antenna 1

he

,zI0

(h+h)/

h/2h/2


Horizontal antenna 1

5.2.Induction Coil

227

227

1/31/2hh


Horizontal antenna 1

5.3.

2280.20.5m151503mm

228

h/=300m15mA6.5%,1203mm90m93.3%

2290.51m380.150.2

229


Horizontal antenna 1

2.2.2 T

T

1. T

T2210TT

2210 T

lhhTh/0.15T2211

2211 T


Horizontal antenna 1

2214

(a)(b)

2213

THT2212

2212 T

2.

2213

9.22214a30602214(b)


Horizontal antenna 1

2215

3.

L22152216

Tl

2216


Horizontal antenna 1

1l2217(a)hhl2217(b)

l,h

l,h

l,h

l,h

2217


Horizontal antenna 1

2lH2217c

3lH221822 17(d)

l,h

l,h

2218 hl

2217


Horizontal antenna 1

HEEz2219(a)122219(b) EEz

Ez

2219


Horizontal antenna 1

2.2.3

Helical Whip Antenna

22202/3

2220


Horizontal antenna 1

(Helical Antenna)DD/2221D/<0.182221(a)22 21(b)D/=0.250.46(3.2)2221cD/>0.46


Horizontal antenna 1

N2222E

DE

lsin90

AR

2222


Horizontal antenna 1

D<<EE

1.55%


Horizontal antenna 1

2.2.4

VHF/4(Elevatedfeed Whip Antenna)


Horizontal antenna 1

2223

2223

(a)(b)(c)


Horizontal antenna 1

2223

(a)(b)(c)


Horizontal antenna 1

2223

(a)(b)(c)


Horizontal antenna 1

2223(c)10

2223

(a)(b)(c)


Horizontal antenna 1

3076MHz3m30MHz0.376MHz0.77

2223

(a)(b)(c)


Horizontal antenna 1

2.2.5

(Biconical Antenna)2224

2224


Horizontal antenna 1

1.

(Discone Antenna)19452225

VHFUHF51501.5

2225

DCminCminS

S=0.3CminD=0.7Cmaxh=30Cmin=L/22L1.571291


Horizontal antenna 1


Horizontal antenna 1

HE2226

2226


Horizontal antenna 1

2227

2227


Horizontal antenna 1

2.

2228(Sleeve Monopole)2228aL+L/2

2228


Horizontal antenna 1

Haeai<aeaoaoai2229

2230

,Zin1LZin2L+2L2229

2229

2230


Horizontal antenna 1

,

L/L=2.2541,221

221


Horizontal antenna 1

(Opensleeve Antenna)2231310MHz510MHz,501.8

2231


Horizontal antenna 1

2.3

C=2b0.2,


Horizontal antenna 1


Horizontal antenna 1

90

90

90

90

90

90

90

90

90

120

60

120

120

60

60

120

60

120

120

60

60

120

60

120

120

60

60

150

150

30

30

30

150

150

150

150

30

30

150

150

30

30

30

30

150

180

180

180

180

0

0

0

180

180

0

0

0

0

0

180

180

0

180

210

210

210

210

210

210

210

210

210

330

330

330

330

330

330

330

330

330

240

240

240

240

300

300

300

300

240

240

300

240

300

300

300

240

240

300

(d) q(f=0,a=0.15l)

(b) q(f=0,a=0.01l)

(c) q(f=0,a=0.0935l)

(i) q(f=0,a=0.48l)

(h) q(f=0,a=0.4l)

(g) q(f=0,a=0.35l)

(e) q(f=0,a=0.2l)

(f) q(f=0,a=0.285l)

(a) q(f=0,a0.001l)

270

270

270

270

270

270

270

270

270

f=0


Horizontal antenna 1

2.3.1

1231(Small Loop Antenna)

231

IS

Rl:


Horizontal antenna 1

ab

D=1.5


Horizontal antenna 1

As the current is along the x direction,b is the length of the block, and w c is the equivalentcross-sectionslarea with w as its width and c as its thickness


Horizontal antenna 1

231/25

10


Horizontal antenna 1

/2/42300MHzNN2(NNINE1N2P1)

N

,Rp;R0,


Horizontal antenna 1

232b=/25a=10-4410-45.7107(S/m)f=100MHz8Rp/R0=0.38

8

8

8


Horizontal antenna 1

232R'r

232

Rre

Q


Horizontal antenna 1

2.3.2

1. J.E.Storer,233231=2ln(2b/a)ab

kb=0.1,kb=0.2 kb,kb=0.20.030.04kb=1=0180=90270

233


Horizontal antenna 1

C2b=23 1

A

,r-1

231

R


Horizontal antenna 1

RA2311A

yOz90kb=1

,J0J202xOz0180


Horizontal antenna 1

2312 ;

yOz: f()=cosJ0(sin)+J2(sin) (2317)

xOz: f()=J0(sin)-J2(sin) (2318)

234

234

(a)yOz(b)xOz

0.27


Horizontal antenna 1

235

(a)(b)

236

0kb=2b/=C/2.5 C()2Xin=2ln(2b/a) 9 kb>1(kb=1

8100

236z


Horizontal antenna 1

2.

237(0.30.5),0.52L4L6L238

1

234

238

(a)2L(b)4L(c)6L

237


Horizontal antenna 1

kb1100239a0.272L239b,,

239 2L

(a)(b)


Horizontal antenna 1

2L4L6L2310a2310bH=0.252L4L6L2310c

2310

(a)(b)(c)


Horizontal antenna 1

1.05161.120

2.3.3

()(Loaded Circular Loop Antenna)2311VHF

2311


Horizontal antenna 1

RLZ0

kb2312a=2ln(2b/a)bRL3259.4300kbkb200300

2312

(a)(b)


Horizontal antenna 1

kb1,2311kb>1,C/,C/min1

2311

1


Horizontal antenna 1

8.6.1 Surface resistance

Let the electric field intensity in a good conductor be

Neglecting the displacement current density in a good conductor, the total current is

The average power dissipated per unit volume is


Horizontal antenna 1

Let us concentrate on a region bounded by 0<x<b,0<y<w,and 0<z<.Then the total power dissipated within this region is

The total current along the x direction is

If R is the resistance of the block ,then the power that it dissipates is


Horizontal antenna 1

Comparing (6.68)and (6.69),we obtain the resistance of the block as

As the current is along the x direction,b is the length of the block, and w c is the equivalent cross-sectionsl area with w as its width and c as its thickness

The skin resistance() or surface resistance() is defined as the resistance of a plane conductor of unit length (b=1),unit width(w=1),and thickness c


Horizontal antenna 1

As the current is along the x direction,b is the length of the block, and w c is the equivalentcross-sectionslarea with w as its width and c as its thickness


Horizontal antenna 1

Although we have computed the skin resistance on the basis that a plane wave is propagating through a flat block,(8.71)can also be used to obtain an approximate value of the skin resistance for a cylindrical conductor.when the current is along the length of a cylindrical conductor of radius a such that a> c ,the skin resistance per unit length is


Horizontal antenna 1

2.4 P91

YagiUdaantenna

(YagiUda Antenna)Uda1926Yagi1927241() 241

241


Horizontal antenna 1

1.(Director)(Reflector)

1.1

242

(a)2(b)2

a212();b212()


Horizontal antenna 1

242

(a)2(b)2

211/2

E2E1

a=0E=1.5E1,=180E=0.5E1,122


Horizontal antenna 1

d0.1~0.4212MN243

2M2

I2=mI1ejd=0.1~0.4

ME2E1=+kdNE2E1

=-kdd0.1~0.4,36kd1440<<180I2I1N2-180<<0I2I1M2

243

d/0.42

0<<180 2

-180<<02


Horizontal antenna 1

2.4.1


Horizontal antenna 1

z

2:

1:

2l

2

2l

1

y

x

d

2.4.2

244

?24412l122l2dI2,I22


Horizontal antenna 1

U1=I1Z11+I2Z12

U2=I1Z21+I2Z22 =0

m(2l1,2l2)d


Horizontal antenna 1

241 2l1/=0.475


Horizontal antenna 1

245 ;

12l1/2l2/d/d/ 2d/2l2/=0.450d/=0.1d/0.25 3d/d/<0.4

245


Horizontal antenna 1

3.(Multiple Element Antenna)

246a

246

(a)(b)E (c)H(d)


Horizontal antenna 1

24112132zz246bcd2lr=0.52l0=0.472l1=2l2=2l3=2l4=0.43dr=0.25d1=d2=d3=0.302a=0.0052EH

246 (a)(b)E (c)H(d)


Horizontal antenna 1

2470.150.0025

N=3N=41dB78N=9N=100.2dB

247


Horizontal antenna 1

2.4.2

242EH

242


Horizontal antenna 1

1.

70()U(5075)2

,2


Horizontal antenna 1

2.

MoM

248L(244)248,HEHE

248L/>220.5L/

248 20.5~L/


Horizontal antenna 1

HE(242)242249

249


Horizontal antenna 1

3.

2410L/10,

90%1,

G=DD245

2410 D~L/


Horizontal antenna 1

4.

5.

S210%

d/


Horizontal antenna 1

X2411X

2411 X

(a)(b)X


Horizontal antenna 1


Horizontal antenna 1

2.4.3

U1/4KK>1

(HalfWave Folded Dipole)24122l/2D<<2412a2412b

2412


Horizontal antenna 1

/22413D<<IM=IM1+IM2

2412

2413


Horizontal antenna 1

2412aIM1=IM2IM=IM1+IM2=2IM1

,Rr,70

IM1IM

=1PinPr246247

IM=2IM1

4


Horizontal antenna 1

42412b

Da1a22412b 2410

a1=a2

a1>a2

a1<a2


Horizontal antenna 1

a1a22414/4a1>a2Zc1<Zc2a1<a2Zc1>Zc2

UM1=UM2=UM248

2414

D

d=2aa

2410


Horizontal antenna 1

,DDD=(0.01~0.03)

K


Horizontal antenna 1

4.9


Horizontal antenna 1

:

zz


Horizontal antenna 1

0z


Horizontal antenna 1

1

1,

ZLZ0


Horizontal antenna 1

Z*GZin

or

2

(1)ZLZ0lZinZGZGZ0

(2)

Z*GZin


Horizontal antenna 1

or

c


Horizontal antenna 1


Horizontal antenna 1

,,,.,,...,,.

1

?

?


Horizontal antenna 1

1.2

I1

I3

I2

I1

I4

(I4)I1I2 I2I3I4I3<I1I4

.(1)I4=0(2)3


Horizontal antenna 1

2

2.1 l/4

I4=0

I1

I3

l/4l/4I40I4

I4


Horizontal antenna 1

2.2

I2I4

I1

I4

I4

I2

I4

(l/4 )Z0 l/4,4I4I44I4

I1

I2I4

I4

I2

I1

I4


Horizontal antenna 1

A

B

U

B

A

2.3 U

U2


Horizontal antenna 1

B

A

U

A

A

ZA2ZA1475ZA475300


Horizontal antenna 1

2.4.5

(Loop Element YagiUda Antenna)2421

3.2dB100

2421


Horizontal antenna 1

brdr

1d=(0.1~0.3)kb=0.9

2kbd0.3dkb=0.7d0.15dd


Horizontal antenna 1

3HE,

4kb0=1.1kbr=1.05dr=0.1kb1

1200MHz1.22520dB


Horizontal antenna 1

2.4.6

2060-20dB-30dB

1.(Back Fire Antenna)

T24 22T13dB3dB

24 22


Horizontal antenna 1

/22dB8dB

1530dB,


Horizontal antenna 1

2.(Short Back Fire Antenna)

24230.40.62W=/4~/2

8.517dB1/10

2423


Horizontal antenna 1

2.12.32.4

2.72.82.102.122.13

123


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