Microsoft Word – HW3
HOMEWORK ASSIGNMENT #3
DATE: Tuesday, June 8, 2021
DUE DATE: Thursday, June 17, 2021
SUBJECT: EECE 5693 – EM Devices
INSTRUCTOR: Prof. Hossein Mosallaei
1) On a small dipole antenna with total length l ( 2.0l ) the current distribution can be
approximated by lzII 210 , as shown below.
a) Find the radiated electric and magnetic fields (Far-Fields). Carefully explain their behaviors and
the physics behind them,
b) Determine the radiation intensity ),( U ,
c) Evaluate the total radiated power rP ,
d) Derive the directivity of antenna ,D . What is mD (maximum directivity) in dB.
e) Plot ,D using a computer program, Explain all the details of the curve carefully (gain, side-
lobes, beamwidth, etc.). In which direction the antenna can radiate maximally? Can we send the
information to point A in space? What do you recommend to send the power to point A?
f) Obtain the Half-Power Beamwidth of antenna from the curve for ,D ,
g) What is the relation between ,D and power pattern ( 2,F )
h) What is the beam solid angel?
i) What is the relation between the directivity and gain of an antenna? How do you define the
efficiency of antenna?
l
r
lzII 210
z
A