ANT0104 Ultra Wideband Omnidirectional Antenna

For the practical measurement of antenna directivity coefficient D, we define it from the dimension of antenna radiation beam range.

Directivity D is the ratio of the maximum radiated power density P(θ,φ) Max to its mean value P(θ,φ)av on a sphere in the far-field region, and is a dimensionless ratio greater than or equal to 1. The calculation formula is as follows:

In addition, directivity D can be calculated by the following formula:

D = 4 PI / Ω _A

In practice, the logarithmic calculation of D is often used to represent the directional gain of an antenna:

D = 10 log ⁡ d

The above directivity D can be interpreted as the ratio of the sphere range (4π rad²) antenna beam range ω _A. For example, if an antenna radiates only to the upper hemispherical space and its beam range is ω _A=2π rad², then its directivity is:

If the logarithm of both sides of the above equation is taken, the antenna's directional gain relative to isotropy can be obtained. It should be noted that this gain can only reflect the antenna's directional pattern radiation, in unit of dBi, since transmission efficiency is not considered as the ideal gain. The calculation results are as follows:

3.01 class: : dBi d = 10 log ⁡ 2 material

The antenna gain units are dBi and dBd, where:

DBi: is the gain obtained by the antenna radiation relative to the point source, because the point source has ω _A=4π and the directional gain is 0dB;

DBd: is the gain of antenna radiation relative to half-wave dipole antenna;

The conversion formula between dBi and dBd is:

2.15 class: : dBi 0 DBD material