relation between beam width and distance of propagartion

[tech_pro]

Hi

I would like to know that wat is the relation b/w the beam width and the distance the signal will propogate


regards
uzmeed

 

[vfone]

Relation is just intuitive. Generally narrow beamwidth means higher antenna gain in particular direction. Narrow beamwidth also helps getting less unwanted reflections, that can affect the signal.
Otherwise wave propagation is affected by propagation modes (ground wave, sky wave, line of sight, non-line of sight, etc) and by wave polarization (linear, circular, etc).

 

[Azulykit]

There is a subtile point here.

Beamwidth and communication distance are not necessarily correlated.

It is correct that reducing beamwidth generally increases gain. That is helpful in increasing communication distance if one is in the antenna mainbeam.

Think if this as viewing the world through a soda straw or telescope. If you happen to be pointed in the appropriate direction life is good and you can see great detail. Point in the wrong direction and you see nothing.

This is why in mobile communications lower gain is sometimes preferable. High gain and low beamwidth is not necessarily better.

Azulykit


You might also find the one-way radar range equation (Friis transmission formula) useful to study the relation between antenna parameters and link distance. There are some interesting twists here too just to keep everyone arguing. IEEE/TAP Antenna Magazine had a feature "Fun with Friis" a number of years ago that was helpful. Friis will get you a relationship between beamwidth and distance after a bit of manipulation.

 

[biff44]

since RF signals propagate forever, the beamwidth obviously has nothing to do with their "propagation distance". If this was not true, then any stellar radio source, which has no directive beamwidth to it, could not possibly travel thousands of light years and be picked up by radio telescopes here on earth.