Multimediální učebnice

Slovník pojmů

Antenna gain

As the gain of the antenna, the maximum value of the directivity factor (in decibels) is understood

G_{a b s} = 10 \log (D_{m a x})

This gain is called the absolute one. The relative gain tells us, how much is the maximum directivity factor higher that the directivity factor of the reference antenna:

G_{r e l} = 10 \log (\frac{D_{m a x}}{D_{r e f}})

As the reference antenna, the half-wavelength long dipole is usually considered.

Directivity factor D(φ, ϑ) describes the directivity of the antenna radiation: directivity factor is higher than one in those directions, where the radiation is concentrated, and is smaller than one in those directions, where the radiation is suppressed. Directivity factor of the isotropic source equals to one.

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