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HW9

This document contains three problems involving antennas. Problem 1 involves calculating various parameters for a folded dipole antenna with given specifications. Problem 2 involves calculating the characteristic impedance needed for a quarter wave transformer matching circuit between a half wave dipole and a transmission line. Problem 3 involves calculating the radiation resistance and directivity of a half wave monopole antenna above a perfectly conducting ground compared to a dipole.

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17 views1 page

HW9

This document contains three problems involving antennas. Problem 1 involves calculating various parameters for a folded dipole antenna with given specifications. Problem 2 involves calculating the characteristic impedance needed for a quarter wave transformer matching circuit between a half wave dipole and a transmission line. Problem 3 involves calculating the radiation resistance and directivity of a half wave monopole antenna above a perfectly conducting ground compared to a dipole.

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gulsahozkaya2000
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We take content rights seriously. If you suspect this is your content, claim it here.
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EED 4106

ANTENNAS AND PROPAGATION


HW9

P.1) There is a folded-dipole antenna with the length L=1.25λ. It is made up of thin wire of
radius a=0.0005λ. The small distance between the folded dipole wires is d=12.5a. This
antenna is fed from one side of wire center and 300 ohm transmission line is connected to it.
The coming power to the antenna from the transmission line is 100 mW.
a) Find the reflection mismatch at the input of the antenna.
b) Find the input antenna current (assume that the input current is real number).
c) Find the input current of the antenna at antenna mode.
d) Find the radiated power density along maximum radiation direction.
e) Find the directivity of this folded dipole antenna.

P.2) A half wavelength (L=0.48λ) dipole is off-center fed with a shift of z f  3 / 16 . This
antenna is tried to be matched with a quarter wave tranformer matching circuit to a
transmission line of characteristic impedance 100 ohm. Find the characteristic impedance
used in this λ/4 - transmission line part used in this matching circuit.
P.3) There is a monopole half-wave antenna (L=0.48λ) located vertically on a perfectly
conducting ground (pec). It is fed from the one end in the vicinity of the pec ground.
a) Find its radiation resistance compare to the free space single dipole with same length.
b) Find its directivity compare to the free space single dipole with same length.

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