/ɡeɪn/
noun … “Measure of how effectively an antenna radiates or receives energy.”
Gain is a quantitative measure of the ability of an Antenna to direct or concentrate radio-frequency energy in a particular direction compared to a reference, typically an isotropic radiator or a dipole. It combines both directivity and efficiency, providing insight into how much power is effectively transmitted or received along a desired path versus all other directions. Higher gain indicates stronger signal strength in a preferred direction, which can improve range and signal-to-noise ratio for communication systems.
Key characteristics of Gain include:
- Directivity: measures how focused the radiated energy is toward a specific direction.
- Efficiency: accounts for losses due to antenna materials, impedance mismatch, or environmental factors.
- Reference standards: typically expressed in dBi (decibels relative to an isotropic antenna) or dBd (decibels relative to a dipole).
- Polarization consistency: high gain is meaningful when aligned with the polarization of the transmitted or received signal.
- Impact on coverage: directional antennas with high gain concentrate energy along a narrow beam, whereas low-gain antennas radiate more uniformly.
Workflow example: In a point-to-point wireless link, engineers choose a parabolic dish antenna with a gain of 30 dBi to focus energy along the direct path between two locations. The high gain compensates for path loss over long distances, improving received signal quality. By contrast, for a Wi-Fi hotspot serving multiple users, an omnidirectional antenna with lower gain is selected to cover a broad area evenly.
-- Example: calculate effective isotropic radiated power (EIRP)
transmit_power = 1.0 -- Watts
antenna_gain = 30 -- dBi
eirp = transmit_power * (10 ** (antenna_gain / 10))
print("EIRP: " + str(eirp) + " Watts")
-- Output: EIRP: 1000 WattsConceptually, Gain is like a flashlight beam: a focused, high-gain antenna concentrates energy like a narrow spotlight, reaching farther, while a low-gain antenna spreads energy broadly like a lantern, illuminating a wider area but with less intensity.
See Antenna, Wavelength, Radio, Modulation, Signal-to-Noise Ratio.