These are the areas where the power is wasted. The other parts of the pattern where the radiation is distributed side wards are known as side lobes or minor lobes. The direction of this lobe indicates the directivity of the antenna. This is the portion where maximum radiated energy exists. The major part of the radiated field, which covers a larger area, is the main lobe or major lobe. Here, the radiation pattern has main lobe, side lobes and back lobe.

To have a better understanding, consider the following figure, which represents the radiation pattern of a dipole antenna. In the representation of radiation pattern, we often come across different shapes, which indicate the major and minor radiation areas, by which the radiation efficiency of the antenna is known. H-plane represents the Horizontal pattern, whereas V-plane represents the Vertical pattern. The figures show the Omni directional radiation pattern in H and V planes as explained above. These resultant patterns are known as Horizontal pattern and Vertical pattern respectively. Two-dimensional pattern can be obtained from three-dimensional pattern by dividing it into horizontal and vertical planes. This clearly indicates the three co-ordinates (x, y, z). The given figure is a three dimensional radiation pattern for an Omni directional pattern. The radiation pattern is a three-dimensional figure and represented in spherical coordinates (r, θ, Φ) assuming its origin at the center of spherical coordinate system. They are plotted on logarithmic or commonly on dB scale. The power patterns are plotted as a function of square of the magnitude of electric and magnetic fields. The field patterns are plotted as a function of electric and magnetic fields. The radiation patterns can be field patterns or power patterns. The arrows represent directions of radiation. The energy being radiated is represented by the patterns drawn in a particular direction. The figure given above shows radiation pattern of a dipole antenna. Let us look at the pattern of energy radiation. Radiation Patterns are diagrammatical representations of the distribution of radiated energy into space, as a function of direction. The energy radiated by an antenna is represented by the Radiation pattern of the antenna. This is a mathematical function of radiation properties of the antenna represented as a function of spherical co-ordinates, E (θ, Ø) and H (θ, Ø). Graphically, radiation can be plotted as a function of angular position and radial distance from the antenna. The power when radiated from the antenna has its effect in the near and far field regions. One can simply understand the function and directivity of an antenna by having a look at its radiation pattern. In any illustration, the sketch drawn to represent the radiation of an antenna is its radiation pattern. Radiation is the term used to represent the emission or reception of wave front at the antenna, specifying its strength.

Spiral antenna radiation pattern