Bài giảng Electromagnetic Fields – Prob - Chapter 8

Electromagnetic Fields – Prob – ch_8

P8.1:

Electromagnetic Fields – Prob – ch_8

P8.2:

jlI₀sin

4λr

jlI₀sin

e^{− jβr}H_=

e^{− jβr}

(Ans:

E_θ=

4λr

2 2

0

32²r²

2

P = ^{l I sin }

l

R_bx= 20²

P =10²I₀²

(

_

)

(

_

)

bx

r

Electromagnetic Fields – Prob – ch_8

P8.3: Find the amplitude I_mof the current with which a Hertzian

dipole of length 0.5 m has to be excited at a frequency of 10 MHz to

produce an electric-field intensity of amplitude 1 mV/m at a distance

of 1 km broadside to the dipole , in free space ? What is the time-

average power radiated for the computed value of I_m?

P8.4:

(Ans: 500 mA , 158 mW )

Electromagnetic Fields – Prob – ch_8

P8.5: An antenna in air radiates the following farfield electric field :

5

E = sin(2θ).e^{− jβr}a_θ(V/m)

r

Determine the total power radiated by this antenna ?

(Ans: 222 mW )

P8.6*:

(Ans: a) 712mA b) 15.8mW c) 149W/m²d) 96.9% )

Electromagnetic Fields – Prob – ch_8

P8.7:

(Ans: a) 0.0637 + j0.2689 , 1.764, 92.37% b) – 0.0204 , 1.042, 99.96% )

Electromagnetic Fields – Prob – ch_8

P8.8:

(Ans: 75.4  )

P8.9:

2

(Ans: a)  = /2,  = 0,  b) 9I₀sin²cos² c) 4.77dB d) 4/3 sr e) 90^o)

Electromagnetic Fields – Prob – ch_8

P8.10:

(Ans: a) 29.7% b) – 3.5 dB c) 67.6 A and 269 W )

Bài giảng Electromagnetic Fields – Prob - Chapter 8 - Trần Quang Việt