Starlink satellite internet is different from cell phone mobile data in several ways.
Starlink “Base station” is much further away
As with any other satellite communications, the sattelites are far away , typically at distance of around 550km (342 miles). This makes the “base station” at least two orders of magnitude further away than terrestial cell phone base stations.
Starlink uses millimeter waves
Starlink uses order of magnitude shorter wavelengths going into the millimeter waves (MMWs).
From Starlink satellites to the customer’s terminal on the ground they use 10.7-12.7 GHz and 37.5-42.5 GHz. From the customer’s terminal back up to the satellites in orbit are handled in the ranges 14-14.5 GHz, 47.2-50.2 GHz, and 50.4-51.4 GHz.
Starlink uses directed beams
Starlink uses directed beams to transmit internet data between its satellites and ground stations, as well as between the satellites themselves. Client devices on the ground, such as the Starlink user terminal (dish), also direct beams to communicate with the satellites. This is achieved through a phased-array antenna embedded within the dish. This two-way beamforming between the ground terminal and the satellites is key to enable communication between such low power output devices. Focusing the radiation in principles also seeks to minimize any radiation that leaks aside.
Starlink client’s antenna output power is around hundred times more powerful than cell phone’s output
The RF (radio frequency) power output of a Starlink ground terminal (the user dish) is relatively low due to regulatory constraints. While the individual RF power output of each antenna element is low (few Watts), the overall effective radiated power (ERP), which takes into account the directional gain of the phased-array antenna, can be significantly higher. Phased-array systems focus energy into narrow beams, effectively increasing the strength of the signal in the direction of the satellite, despite the low RF output. The total RF power output from the Starlink user ground dish is a combination of the power output from each individual antenna element in the phased-array system. While the exact number of antenna elements in the Starlink user dish hasn’t been publicly disclosed, we can make a reasonable estimation based on general phased-array principles and available information. Each antenna element in the phased array might have an RF power output between 1 to 3 watts. The total RF output is not a simple sum of the individual element power, because phased-array systems direct power in a specific direction, thus focusing energy. However, assuming a dish has hundreds of elements (a common configuration in such systems), the combined power, after considering directional gain, could be significantly higher in the direction of the signal. Based on available specs and common design for similar systems, the total RF power output (before directional gain) might range from 50 to 100 watts. However, due to the narrow beamforming, the effective radiated power (ERP) could be much higher, possibly in the range of tens of kilowatts, depending on how focused the beam is.
References: https://www.americantv.com/what-frequency-does-starlink-use.php
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