What is Half Power Beam Width (HPBW)?

What is HPBW or Half Power Beam Width?

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- everything RF

Jan 23, 2021

Half Power Beam Width or HPBW is an angular width (in degrees), measured on the major lobe of an antenna radiation pattern at half-power points i.e the points at which the signal power is half that of its peak value. In other words, The Half Power Beamwidth (HPBW) is the angular separation in which the magnitude of the radiation pattern decreases by 50% (or -3 dB) from the peak of the main beam.

The 3 dB points on the major lobe of the antenna are the half power points. These points are at -3 dB from where the point of maximum amplitude. When a line is drawn between radiation pattern’s origin and the half power points on the major lobe, on both the sides, the angle between those two vectors is termed as HPBW, half power beam width.

We know, the energy radiated by an antenna is characterized by its Radiation pattern. The Radiation Pattern of an antenna is a diagrammatic representation of the distribution of radiated energy into space, as a function of direction. Beam width is the area where most of the power is radiated, which is the peak power.

In the radiation pattern, the main lobe is the main beam of the antenna where maximum energy is radiated by the antenna. Beam width is the area where most of the power is radiated, which is the peak power.

Half power beam width is the angle in which relative power is more than 50% of the peak power, in the effective radiated field of the antenna. This is considered to be the part of the antenna output that has maximum consistency and utility and is closely related to the gain of the antenna. If planning an antenna array, the HPBW will be the point where neighboring sectors cross over.