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A small, often portable, ground-based satellite communications station with a dish antenna, usually ranging from 0.75 to 1.2 meters in diameter. VSATs are widely used for internet access, data transmission, and remote network management.

The time it takes for a signal to travel from the satellite to the receiver or vice versa. Propagation delay is significant in GEO satellite communication due to the long distances involved, typically around 120 milliseconds (one-way).

The orientation of the electric field of the radio wave. In satellite communications, common polarizations are linear (horizontal or vertical) and circular (right-hand or left-hand), which can help to reduce interference and increase bandwidth efficiency.

The reduction in signal strength as it travels through the atmosphere or free space. Signal attenuation can be caused by distance, environmental factors like rain or buildings, and is an important factor to consider in communication link budgets.

A group of satellites working together as a system to provide global or regional coverage. Constellations can be arranged in various orbital planes and use different altitudes, such as the GPS (Global Positioning System) and Starlink constellations.

The calculation of total gain and loss in a communication system to determine the received signal strength. A link budget takes into account factors like transmitter power, antenna gains, free-space loss, and atmospheric attenuation.

The process of varying a carrier signal in order to transmit information. In satellite communications, common modulation schemes include Phase Shift Keying (PSK), Frequency Modulation (FM), and Amplitude Modulation (AM), which are used to encode digital data onto the carrier wave.

The ratio of the carrier signal power to the noise power in a communication channel, typically expressed in decibels (dB). A higher C/N ratio indicates a better quality signal and higher potential data rates.

The angular width of the radio beam transmitted or received by an antenna, typically measured at the half-power (-3 dB) points. A smaller beamwidth implies a more concentrated and directional signal, which can be beneficial for targeted communication.

A circular orbit located at approximately 35,786 kilometers (22,236 miles) above Earth's equator, where a satellite's orbital period matches the rotation of the Earth. Satellites in GEO appear stationary relative to an observer on Earth and are commonly used for telecommunications and broadcasting.

An orbit around Earth with an altitude between 160 to 2,000 kilometers. Satellites in LEO have a short orbital period (typically 90 to 120 minutes) and are often used for Earth observation, imaging, and communications networks like Iridium and Globalstar.

An orbit with an altitude between 2,000 and 35,786 kilometers. Satellites in this region, such as those in the GPS constellation, have longer orbital periods than LEO but shorter than GEO and provide services like navigation and regional communication.

The area on the Earth's surface over which a satellite's transponder can communicate. The size and shape of the footprint are determined by the satellite's antenna and its altitude. Higher altitude satellites have larger footprints.

The transmission of a signal from an Earth station to a satellite. Uplink frequencies are generally in the microwave range and require careful aiming of the Earth station's antenna toward the satellite.

A technique in satellite communications that allows the use of the same frequency bandwidth for different spatial or polarization channels, effectively doubling the capacity of a communication system without requiring additional spectrum.

A method used to combine multiple signals into one for transmission over a shared medium. Types used in satellite communications include Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), and Code Division Multiplexing (CDM).

Two angles used to position a satellite antenna. Azimuth is the rotation angle around a vertical axis (bearing from True North), and elevation is the angle above the horizon. Both are crucial for accurately pointing an antenna towards a satellite.

The range of frequencies used to transmit a signal or the data transfer capacity of a communication link. In satellite communications, bandwidth is limited and must be allocated efficiently to avoid wasting spectrum resources.

A radio transmitter and receiver housed within a satellite that receives, amplifies, and retransmits signals back to Earth. It plays a crucial role in satellite telecommunications for both uplink and downlink pathways.