Satellite TV Reception: Components, Signal Quality, and Installation

Satellite Antenna Components

The Dish: This antenna is designed to capture high-frequency electromagnetic waves, typically from satellites. It consists of the following parts: the parabolic reflector disk, the external drive (LNB), and the support rods for the reflector.

Indoor Unit: This unit receives the intermediate frequency signal from the converter. It prepares the radio frequency signal for the TV receiver through the following stages: 1st to 2nd IF conversion, demodulation, video processing, audio processing, and RF modulation.

Satellite Antenna Alignment

Pointing the Antenna: Reception quality depends on the antenna and the precise orientation of the reflector toward the satellite. You must consider two specific angles: azimuth and elevation.

Receiving Station Parameters

Transmitting signals can cause interference, resulting in noise. Key metrics include noise power, noise figure, noise factor, carrier-to-noise ratio, signal-to-noise ratio, the figure of merit, and power flux density.

Noise Metrics

• Power Noise: Amplified antennas and converters generate noise because incoming signals are extremely weak.
• Noise Figure and Noise Factor: The noise figure is generated within device components due to the thermal agitation of electrons, creating unwanted signals dependent on temperature.
• Carrier-to-Noise and Signal-to-Noise: These parameters determine the quality of the signal received from a satellite channel. The signal-to-noise ratio is the ratio between the useful signal power and the noise power, measured in dB.
• Power Flux Density: Indicates the signal power per square meter reaching the installation site of the receiving antenna.

Installation and Cabling

Mounting the Antenna: If the antenna is large, it should be installed on a concrete pad on the roof or a wall. Smaller antennas can be mounted on a standard terrestrial TV mast. The installation must be free of obstacles and account for wind loading.

Cables and Connectors: High-frequency satellite TV requires high-quality components. Poor cabling leads to high signal attenuation and degrades the carrier-to-noise ratio. Use coaxial cables with very low attenuation and limited length, utilizing Type F connectors.

Antenna Characteristics

• Gain: The relationship between the output level of the antenna and an isotropic antenna.
• Bandwidth: The frequency range the antenna is capable of capturing.
• Directivity: The main radiation lobe should be very narrow; the direction angle is measured from the antenna's azimuth.