What is antenna gain typically specified in?

What is antenna gain typically specified in?

• A. Decibels over isotropic (dBi)
• B. Decibels over the dipole (dBd)
• C. Watts per steradian
• D. Hertz per second

Answer: (A)

Antenna gain is a measure of how well an antenna concentrates power in a chosen direction, and it’s most often given as dBi, decibels over isotropic. Using isotropic as the reference means you’re comparing the antenna’s performance to a hypothetical perfect radiator that emits equally in all directions, which provides a universal, easy-to-compare standard. Seeing gain in dBi makes intuitive sense: if an antenna has a gain of 6 dBi, it delivers about four times more power in its main direction than the same input power would from an isotropic radiator (10^(6/10) ≈ 4). There’s also a convention using dBd, which compares to a half-wave dipole as the reference; that shifts the numbers by about 2.15 dB relative to dBi, since a dipole itself has inherent directivity. The other options don’t fit because watts per steradian describes radiated power density (not gain relative to a reference), and hertz per second is a unit of frequency, unrelated to antenna gain.

Antenna gain is a measure of how well an antenna concentrates power in a chosen direction, and it’s most often given as dBi, decibels over isotropic. Using isotropic as the reference means you’re comparing the antenna’s performance to a hypothetical perfect radiator that emits equally in all directions, which provides a universal, easy-to-compare standard.

Seeing gain in dBi makes intuitive sense: if an antenna has a gain of 6 dBi, it delivers about four times more power in its main direction than the same input power would from an isotropic radiator (10^(6/10) ≈ 4). There’s also a convention using dBd, which compares to a half-wave dipole as the reference; that shifts the numbers by about 2.15 dB relative to dBi, since a dipole itself has inherent directivity.

The other options don’t fit because watts per steradian describes radiated power density (not gain relative to a reference), and hertz per second is a unit of frequency, unrelated to antenna gain.