Sponsored Links
This presentation is the property of its rightful owner.
1 / 150

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


  • 152 Views
  • Uploaded on
  • Presentation posted in: General

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.

Download Presentation

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;

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


2.1

(Horizontal Antenna)

1

2

3


2.1

2.1.1

(Horizontal Symmetrical Dipole)36mm23m/4


211

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


z

P

q

H

A

O

D

y

j

x

1.

212

-1


213213214

213


213213214

214


z

P

q

H

A

O

D

y

j

x

EH

l<0.7H212xOzrOPPzP


1

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

xOz1174


1

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

(1)H/l/H/

(2)H/=0

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


(4)H/>0.3H/m1m1172

m100H

0

(5),


2 213:

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


215216l/=0.25l/=0.50

215 l/=0.25

216 l/=0.5


(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


(1)

(2)H/0.3,,0300km

(3)

(4)=0l/0.7


2.

,217

217 l=20mH=6m


3.

,f(m1,)m1 2 15;Rr

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

218 D~l/


4.

1) l

(1)

l<0.7minmin(=0)


(2)

l/Al/0.1219l0.2

l0.2max (2110)

219 K~l/

0.2maxl0.7min (2111)

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


2) H

300km,H=(0.10.3)815m

m10

216H

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


2.1.2

64m210222=64m4mm1k350

1.75ma


(Cage Antenna)21106835mm13m250400

2110


34m

ae:

abna2mmb1.5mn8ae0.85m64m353.6


2111a2111b354637434(2111(a))

2111

(a)(b)


211221132114

2112

2114

2113


2.1.3 V20

1l/=0.635Dmax=3.296

l=90202115V(Vee Dipole)

1

2

V1.4

,Im;l;r;


V

1

2

V=0V

,V2116

2116 V


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

2opt

2116 V

V20VV


0.5V

3V

2l,

1

2

3

4LPDA


2.1.4

1.


2.

(1):,

(2)

(3)


1.

112VHF48.5~223MHz1368UHF470958MHz


888()


2.

(Turnstile Antenna)

211790


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

2120kr2120t=08E882118a

2118


5%2118b

2118

8


3. VHF(Batty Wing Antenna)2119EE2120

EE

2119


AEEDCBADA150/2


2121

11.12025%

2

3

2121


75


2.2

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

221


H(HH)

1

2Q

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

f/f02f


2.2.1

(Whip Antenna)221222

1.

1

2

1.72H/<0.13

222

(a)(b)


3

1.2.8

He

223

,I0;H

223

H/<0.1


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

4

224Rin=Rr0+Rl0 (224)

Rr0Rl0:

A72

224


5:H1%

5.1.

225(TopLoading)226

225

226


H226(a)226(b)CaZ0H:

226

,H;ah0=h+h

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


he

,zI0

(h+h)/

h/2h/2


5.2.Induction Coil

227

227

1/31/2hh


5.3.

2280.20.5m151503mm

228

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

2290.51m380.150.2

229


2.2.2 T

T

1. T

T2210TT

2210 T

lhhTh/0.15T2211

2211 T


2214

(a)(b)

2213

THT2212

2212 T

2.

2213

9.22214a30602214(b)


2215

3.

L22152216

Tl

2216


1l2217(a)hhl2217(b)

l,h

l,h

l,h

l,h

2217


2lH2217c

3lH221822 17(d)

l,h

l,h

2218 hl

2217


HEEz2219(a)122219(b) EEz

Ez

2219


2.2.3

Helical Whip Antenna

22202/3

2220


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


N2222E

DE

lsin90

AR

2222


D<<EE

1.55%


2.2.4

VHF/4(Elevatedfeed Whip Antenna)


2223

2223

(a)(b)(c)


2223

(a)(b)(c)


2223

(a)(b)(c)


2223(c)10

2223

(a)(b)(c)


3076MHz3m30MHz0.376MHz0.77

2223

(a)(b)(c)


2.2.5

(Biconical Antenna)2224

2224


1.

(Discone Antenna)19452225

VHFUHF51501.5

2225

DCminCminS

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



HE2226

2226


2227

2227


2.

2228(Sleeve Monopole)2228aL+L/2

2228


Haeai<aeaoaoai2229

2230

,Zin1LZin2L+2L2229

2229

2230


,

L/L=2.2541,221

221


(Opensleeve Antenna)2231310MHz510MHz,501.8

2231


2.3

C=2b0.2,



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


2.3.1

1231(Small Loop Antenna)

231

IS

Rl:


ab

D=1.5


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


231/25

10


/2/42300MHzNN2(NNINE1N2P1)

N

,Rp;R0,


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

8

8

8


232R'r

232

Rre

Q


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


C2b=23 1

A

,r-1

231

R


RA2311A

yOz90kb=1

,J0J202xOz0180


2312 ;

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

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

234

234

(a)yOz(b)xOz

0.27


235

(a)(b)

236

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

8100

236z


2.

237(0.30.5),0.52L4L6L238

1

234

238

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

237


kb1100239a0.272L239b,,

239 2L

(a)(b)


2L4L6L2310a2310bH=0.252L4L6L2310c

2310

(a)(b)(c)


1.05161.120

2.3.3

()(Loaded Circular Loop Antenna)2311VHF

2311


RLZ0

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

2312

(a)(b)


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

2311

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


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


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


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


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


2.4 P91

YagiUdaantenna

(YagiUda Antenna)Uda1926Yagi1927241() 241

241


1.(Director)(Reflector)

1.1

242

(a)2(b)2

a212();b212()


242

(a)2(b)2

211/2

E2E1

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


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


2.4.1


z

2:

1:

2l

2

2l

1

y

x

d

2.4.2

244

?24412l122l2dI2,I22


U1=I1Z11+I2Z12

U2=I1Z21+I2Z22 =0

m(2l1,2l2)d


241 2l1/=0.475


245 ;

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

245


3.(Multiple Element Antenna)

246a

246

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


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)


2470.150.0025

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

247


2.4.2

242EH

242


1.

70()U(5075)2

,2


2.

MoM

248L(244)248,HEHE

248L/>220.5L/

248 20.5~L/


HE(242)242249

249


3.

2410L/10,

90%1,

G=DD245

2410 D~L/


4.

5.

S210%

d/


X2411X

2411 X

(a)(b)X



2.4.3

U1/4KK>1

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

2412


/22413D<<IM=IM1+IM2

2412

2413


2412aIM1=IM2IM=IM1+IM2=2IM1

,Rr,70

IM1IM

=1PinPr246247

IM=2IM1

4


42412b

Da1a22412b 2410

a1=a2

a1>a2

a1<a2


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

UM1=UM2=UM248

2414

D

d=2aa

2410


,DDD=(0.01~0.03)

K


4.9


:

zz


0z


1

1,

ZLZ0


Z*GZin

or

2

(1)ZLZ0lZinZGZGZ0

(2)

Z*GZin


or

c



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

1

?

?


1.2

I1

I3

I2

I1

I4

(I4)I1I2 I2I3I4I3<I1I4

.(1)I4=0(2)3


2

2.1 l/4

I4=0

I1

I3

l/4l/4I40I4

I4


2.2

I2I4

I1

I4

I4

I2

I4

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

I1

I2I4

I4

I2

I1

I4


A

B

U

B

A

2.3 U

U2


B

A

U

A

A

ZA2ZA1475ZA475300


2.4.5

(Loop Element YagiUda Antenna)2421

3.2dB100

2421


brdr

1d=(0.1~0.3)kb=0.9

2kbd0.3dkb=0.7d0.15dd


3HE,

4kb0=1.1kbr=1.05dr=0.1kb1

1200MHz1.22520dB


2.4.6

2060-20dB-30dB

1.(Back Fire Antenna)

T24 22T13dB3dB

24 22


/22dB8dB

1530dB,


2.(Short Back Fire Antenna)

24230.40.62W=/4~/2

8.517dB1/10

2423


2.12.32.4

2.72.82.102.122.13

123


  • Login