Is the gain of an antenna sufficient to describe the radiation pattern?

Question

Is the gain of a directional antenna (for example Yagi-Uda) the only thing that we need, in order to describe each radiation pattern?

Isn't the gain a function of the azimuth and zenith angle that describes angular dependence of direction and received signal strength?

Answer 1

It matters because your signals may vary over a 40 dB range which is not defined well by the antenna gain as there may be many side lobe nulls. It depends on the skew angle of detection you are using and the type of element, (bar, butterfly, etc) and how those lobes shift with frequency due to phase alignment of the elements.

• For instance , blocking a strong transmitter off-axis while reaching a faint distant one to avoid IMD. Yet -3dB beamwidth and gain are related for 0 to -3dB but not very well below this. I do this to block the CN tower from North of Toronto to get Buffalo just slightly off-axis balancing for max weak SNR without knowing the imperfect patterns of my Yagi-Uda. This way I can get 30 FTA channels using a pre-amp.

ref:

https://www.tvfool.com/ Find what gain you need.

ideal

If elements are not perfectly in alignment, the side lobes may bulge out.

Answer 2

The gain of an antenna is a measure of the overall radiation pattern of that antenna. That means that two antennas can have the same gain but an entirely different shaped radiation pattern. For example, an antenna with only one main lobe of width D degrees and low sidelobes can have a gain of X dB. Another antenna might have two main lobes of width D/2 degrees and low sidelobes. Because the gain represents an integration of the whole pattern, both of these antennas will (roughly) have the same gain.