What is Antenna Signal Gain?
Signal gain is the strength that a booster antenna adds to your internet connection. A booster antenna can enhance the range and power of your connection. When it enhances range, signal is measured in decibels relative to an isotropic radiator (dBi). When it enhances power, it’s measured in decibels relative to a milliwatt (dBm). Gain can also be listed in just decibels (dB).
A booster antenna can increase your download and upload speeds and reduce latency in your internet connection. When you understand signal gain, it’s easy to find the right antenna.
How Does Signal Gain Increase Range?
Antenna signal strength is often measured in dBi, where a higher measurement means a better horizontal range. Because directional antennas only transmit on a single horizontal line, they have higher dBi gains than omnidirectional antennas. In an omnidirectional antenna, which transmits across horizontal and vertical planes, lower dBi can indicate a higher vertical range.
The relationship between dBi and range is fairly stable, though it varies based on the type of antenna. For example, a typical omnidirectional antenna with 2.5 dBi might have a signal range of about 300 feet – while a typical directional log periodic antenna with 8 dBi might have a range of around 1500 feet. In general, each unit of dBi gain can boost range by 100 to 200 feet.
For directional antennas, two design factors really determine dBi signal strength:
The number of elements. A single reflector can increase signal strength by up to 5 dBi and each additional director can increase signal strength by about 1 dB.
The spacing of the elements. A longer antenna with wide spaces between each element will provide higher gains than a compact antenna.
How does Signal Gain Increase Strength?
Antenna signal strength is also measured in dBm, where a measurement closer to -50 dBm is stronger. These signal gains have a direct effect on the overall signal strength of your connection, but not on your internet speeds – however, there is a pretty clear link between signal strength, internet user experience, and estimated download speed.
|Signal Strength||Internet user experience||Estimated download speed|
|-50 dBm to -105 dBm||Strong (clear voice and fast mobile data)||4-80 Mbps|
|-106 dBm to -125 dBm||Fair (good voice and reliable mobile data)||2-4 Mbps|
|-126 dBm to -136 dBm||Bad (good voice, but unreliable mobile data)||0-2 Mbps|
|-136 dBm to -140 dBm||Terrible (voice, but no mobile data)||0 Mbps|
What’s the Difference Between dB, dBi, and dBm Gains?
Antenna signal gains are often listed in dB, which is the ratio of power between two levels. Decibels aren’t an absolute form of measurement, just a relative ratio than can be used to represent gains relative to something concrete like an isotropic radiator (dBi) or milliwatt (dBm). When antennas list dB gains, they’re often using the measurement as a shorthand for dBi.
What’s a Good Antenna Signal Gain?
Most booster antennas promise gains of up to 10 dBi, which can increase your signal range by up to 2000 feet and boost the overall dBm of your fixed wireless connection.