User's Guide

Appendix A. Radio Signal Propagation
User's Guide A-4 BreezeNET BU-DS.11/RB-DS.11
Antenna Characteristics
Isotropic Antenna
A hypothetical antenna having equal radiation intensity in all directions. Used as a zero dB gain
reference in directivity calculation (gain).
Antenna Gain
A measure of directivity. It is defined as the ratio of the radiation intensity in a given direction to
the radiation intensity that would be obtained if the power accepted by the antenna was radiated
equally in all directions (isotropically). Antenna gain is expressed in dBi.
Radiation Pattern
A graphical representation in either polar or rectangular coordinates of the spatial energy
distribution of an antenna.
Side Lobes
The radiation lobes in any direction other than that of the main lobe.
Omni-directional Antenna
Radiates and receives equally in all directions in azimuth. The following diagram shows the
radiation pattern of an omni-directional antenna with its side lobes in polar form.
Figure A-3. Side View
Figure A-4. Top View
Directional Antenna
Radiates and receives most of the signal power in one direction. The following diagram shows the
radiation pattern of a directional antenna with its side lobes in polar form: