Essential TV Antenna and Satellite Concepts

Antenna Amplifiers

Number of amplifier types: Two main types for typical antennas: Monochannel (single channel) and Wideband.

Noise Figure: Indicates the noise level entering the amplifier's signal input.

Signal Quality

Ideal Signal-to-Noise Ratio (S/N) for a perfect image (dB): 57 to 80 dB, with 46 dB being the minimum for acceptable TV viewing.

Standard TV Antenna Impedance: Typically 300 ohms.

Types of Amplifiers

Single-channel amplifiers:

• Amplifier with one input and two outputs.
• Amplifier with two inputs and two outputs.

Power Amplifier Function: Amplifies the signal, allowing for small variations in channel amplification.

TV Antenna Installation

Essential Elements for Successful TV Antenna Installation:

• Antenna
• Cable
• Amplifiers
• Filters / Separators / Attenuators
• Equalizers
• Distributors
• Splitters
• User Outlet

Signal Management Components

Types of Filters:

• High-pass
• Low-pass
• Band-pass
• Band-stop (rejects a specific band)

Antenna Coupler Function: Used to join signals from two antennas.

Distributor Function: Distributes the signal to different outlets.

Bypass Function: Distributes the signal to different branches while maintaining impedance matching.

Masthead Amplifier: A power amplifier placed near the TV mast to boost the signal before it travels down the cable.

Extension Attenuation: Signal attenuation between the antenna and the amplifier.

Bending Moment: Flexure experienced by a metallic element fixed at its ends when a force is applied.

Signal Levels

VHF Signal Level at User Outlet: 57 - 80 dB.

FM Signal Level: 40 to 70 dB.

Digital Signal Thresholds (dB):

• QPSK: 47-77 dB
• 64-QAM: 45-70 dB

Satellite Systems

Fundamentals

Physical Basis of a Parabolic Antenna: Concentrates the signal onto the dish and directs it to the LNB (Low-Noise Block).

Clarke Orbit: Geostationary orbit.

Geosynchronous (Satellite): Rotating at the same angular velocity as the Earth.

Geostationary Satellite Altitude: Approximately 35,806 km.

Satellite Orbit Perturbations: Mainly due to the Sun's gravitational pull and Earth's elliptical orbit.

Sun's Angle of Eclipse on Satellite and Duration: 17.36°, lasting 69' 15".

Pronounced Eclipse Phenomenon: During equinoxes, March 21st and September 22nd.

Frequency Bands and Signal Management

Satellite Frequency Bands: C-band (4 GHz) and Ku-band (12 GHz).

Geosynchronous Satellite Uplink/Downlink Frequencies: Uplink 14 GHz, Downlink 12 GHz.

Frequency Differentiation: To avoid interference.

Interference Avoidance Technique: Change polarization.

Satellite Frequency Changer: Transponder.

Satellite Coverage Area: The area where the satellite signal can be received, also called "footprint".

Satellite Dish Types

• Prime Focus
• Offset
• Cassegrain
• Flat Prime Antenna

DTH and DBS

DTH (Direct-to-Home): Satellite with medium power.

DBS (Direct Broadcasting Satellite): Satellites with high power.

Earth Geometry and Satellite Alignment

Earth Parallels: Divisions of land parallel to the Equator, including the Equator itself.

Terrestrial Meridians: Divisions of land from pole to pole; the Greenwich meridian is 0°, and there are 180.

Azimuth: Horizontal angle to rotate the dish to locate a satellite.

Elevation: Angle to raise the dish to locate a satellite.

Polarization Skew: Angle to rotate the LNB to receive the satellite signal correctly.

Calculating Alignment Angles

Methods for Calculating Alignment Angles:

• Mathematical calculations
• Tables and graphs for each satellite, cable provider, and country
• Abacus or nomogram

Magnetic North and Inclinometer

Magnetic North Pole Location: Approximately 5 to 6 degrees to the right of the geographic North Pole.

Inclinometer Use: To measure elevation.

Inclinometer Function: To adjust antenna elevation, polarization, and skew.

LNB (Low-Noise Block)

LNB Function:

• Receives the signal
• Converts it to Intermediate Frequency (IF) (950 to 2150 MHz)
• Amplifies the signal

LNB Characteristics:

• Sensitivity
• Operating frequency
• Polarity

LNB Types:

• Single (Universal)
• Double / 4 outputs
• Monobloc (Two satellites)

IF Signal Purpose: To reduce cable attenuation and signal losses.

Frequency Bands

B-II VHF Band: Used for FM radio.

B-IV Band: Includes TV channels 21 to 69.