Balluff BIS U Basishandbuch Seite 40

BIS U Basic Manual
4
Reference Antennas and Antenna Parameters
4.1 Reference or
Standard
Antennas
10
Only passive antennas can be connected to the BIS U processor unit. The power of the
antennas is defined by a generally binding parameter set of measurable properties, which
include:
– Antenna gain
– Return loss/VSWR
– Dispersion angle
– Front to back ratio
– Impedance
– Polarization
– Axial ratio
– Power rating
The comparability of different antennas and the quantitative assessment of power radiated by
the antennas are achieved using reference or standard antennas.
The following antennas are used for reference purposes:
Isotropic radiator
Half-wave dipole (λ/2 dipole) The maximum field intensities are vertical in relation to the
If the same radio frequency power is supplied to both antennas, the half-wave dipole has a
higher field intensity than the isotropic radiator in the main dispersion directions. There is a direct
correlation between the two values; the radiated power of a half-wave dipole in the main
dispersion direction is higher than that of the isotropic radiator by a factor of 1.64 (2.15 dB).
Half-wave dipole
Isotropic radiator
Figure 4: Vertical radiation diagram for reference antennas
The isotropic radiator is a hypothetical, lossless antenna that
disperses radiation evenly in all directions. It generates a
power density independent of the angle at distance r.
dipole level. A power density is generated in the shape of a
figure eight.