Technical Appendix; Antenna Gain - Kathrein LORA Anwendungshinweis

8.1

Antenna gain

The gain is the ratio between the radiated power density in the main radiation direction
for the antenna in question and a reference antenna with the same supply power.
Reference antennas are isotropic radiators or λ/2 – dipole
Frequent logarithmic tasks:
- dBi: linear gain based on isotropic radiator
- dBd: linear gain based on dipole
- dBic: circular gain based on isotropic radiator
Isotropic radiator
Pin = 1.256 W
Dipole with gain 1.64 (2.15 dBi)
Pin = 1.256 W
Antenna with gain 4 (6dBi)
Pin = 1.256 W
The isotropic radiator is a loss-free point radiator with an even spherical
radiation pattern in all directions. Its power density is distributed evenly over a
sphere with a surface of 4π²r.
The gain of the λ/2 – dipole is 1.64 and the power density it produces is 1.64 times
as big.
An example antenna with a gain of 6 dBi achieves a power density 6 dB larger
than that of the isotropic radiator.

8. Technical appendix

Power density at 10 m
Power density at 10 m
Power density at 10 m
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