What is the physical significance of Half Power Beam Width and First Null Beam Width of an antenna?
The half-power beamwidth tends to be closely related to the gain of the antenna. It is also important if antennas are to be used to cover neighbouring sectors, as this is the cross-over point. Also the half-power beamwidth is usually the part where the antenna is considered useful.
The first null beamwidth is useful in finding out how much antennas will interfere with each other.
To get a good (as close to 1 as possible) ratio of half-power beamwidth to first null beamwidth usually requires a larger aperture than for poorer ratios, so is more expensive in terms of area required, and cost and weight of antenna. To get narrow first null beamwidth the antenna will usually have less gain than expected from the aperture (but not always).
You can determine the directivity of the antenna, you can determine the resolution of the antenna beam
The half-power beamwidth tends to be closely related to the gain of the antenna. It is also important if antennas are to be used to cover neighbouring sectors, as this is the cross-over point. Also the half-power beamwidth is usually the part where the antenna is considered useful.
The first null beamwidth is useful in finding out how much antennas will interfere with each other.
To get a good (as close to 1 as possible) ratio of half-power beamwidth to first null beamwidth usually requires a larger aperture than for poorer ratios, so is more expensive in terms of area required, and cost and weight of antenna. To get narrow first null beamwidth the antenna will usually have less gain than expected from the aperture (but not always).
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