Transcript Lecture 1 Television Antenna Parts of antenna Formula  = 3,000,000,000 Frequency =Wavelength in meters f= frequency in hertz.

Lecture 1
Television Antenna
Parts of antenna
Formula

=
3,000,000,000
Frequency
=Wavelength in meters
f= frequency in hertz
Wavelength
 Lambda
(meters)
 Velocity
(300,000,000
meters/sec.)
 Frequency (Hz)
 = v/f
Antenna Systems
 Radio
Energy in Space
–300 million meters per second
 E = MC2
 Speed of Light
Wavelength conversion
Meters:
Lambda = 300/211.25 = 1.46 meters
Miles:
Lambda = .186/211.25 = .00088 miles
Feet:
1 meter = 3.28 feet
Lambda = 1.46 meters x 3.28 = 4.79 feet
Spectrum
TV Station
WTHR-TV
Ch.13 (210-216 MHz)
WTHR-TV
WAVELENGTH IN:
A. Meters
B. Miles
C. Feet
Types of Antenna
Dipole
Vertical
Plane
Radiation
Pattern
Monopole
Folded Dipole
Mobile antennas
Reflector
Antenna
Yagi Antennas
Coax Linear
Array
Single elements radiation pattern
Radio Waves

Three important features of radio waves
– amplitude, frequency, and polarization
Modulation by amplitude and frequency
(AM and FM) is common
 Polarization

– rarely used at all
– essentially never to modulate
Polarization
Polarization - the orientation of the electric field
of an electromagnetic wave.
Linearly Polarized Wave
Circularly Polarized Wave
Won’t we pick up both signals?

Polarization is related to antenna
geometry
– Horizontal antennae won’t pick up vertical
waves and vise versa

Circular antennae
– 50% of linear waves
– 100% of a correctly oriented circular wave
– none of a circular wave of opposite
polarization
Current Uses of Polarization

Satellite TV
– Binary circularly polarized signal
– Maybe PM

Military communication--particularly air
to sea communication
– Circularly polarized FM signal
Antenna Design
Sample Antenna
 Basic Design Components
 Equations
 Calculations

Equations
 = c/n
 D = /p
 Gain in dB = 11.8 + 10
log(C2 * n * S)
 C=  for helical
antennae








 = wavelength
c = speed of light
n = frequency
D = diameter of helix
n = # of turns
C = circumference
S = axial distance
between turns
Equations with Numbers





 = c/n=(3x10^8 m/s)/(2.4GHz)=.125 m
D = /p=3.988 cm
S = 3.924 cm
n=6
Gain = 11.8 + 10 log(C2 * n * S) = 7.46 dB
antenna with approx. 4 cm diameter.
for an
Antenna Safety





Think before acting
Do not erect an antenna structure near enough
to a power line allow distance between the two
Do not try to throw-in lead wire from one point
to the another where there is even a remote
chance of power line contact.
Ground all antenna structures properly
Safety check receivers for power line leakage to
the antenna.
continuation
Use standard antenna system connectors
and equipment
 Use power climbing equipment
 Dress correctly hard hat rubber sole etc
 Obtain help to handle heavy or hard
manage equipment.

Experimentation
Frequency Synthesizer
Mixer
TV Tuner
Amplifiers
IF filter
Envelope Detector
Amplifier
Non-coherent detector prototype