Elevation angle of a phased array antenna

[senmeis]

TL;DR

elevation, phased array

Hi,

In the attached slide the elevation angle of a phased array antenna ranges from -25 to +25 degrees. Does it mean EM waves are transmitted on both sides of the elevation plane? Does it make any sense?

 

[RiScJ]

It means that the main lobe of the radiation pattern can be swept in elevation from -25 deg to 25 deg.

 

[Baluncore]

Does it mean EM waves are transmitted on both sides of the elevation plane? Does it make any sense?

The array can be electronically steered to anywhere between 25° down to 25° up. At the same time, it can be steered from 50° left, to 50° right.

 

[senmeis]

As far as I understand all the instruments shall be located on one side of the elevation plane so the radiation on this side is not necessary. Is it correct?

 

[Baluncore]

As far as I understand all the instruments shall be located on one side of the elevation plane so the radiation on this side is not necessary. Is it correct?

It depends on what you mean by instruments, (elements?), and what you mean by elevation plane.
Antennas usually have a front from which radiation is wanted, and a rear from which radiation is not wanted. The difference is specified as a front to back ratio, measured in dB.

With a phased array, there is usually a reflector plane behind the array of elements. That enhances the F/B ratio, and eliminates interference from behind the antenna array. Since the separation between the elements and the reflector can be optimised, that can double the signal, gaining a +3 dB advantage.

 

[senmeis]

For the case with a reflector plane (elevation plane) there’s no radiation behind this plane. Is it true?

 

[Baluncore]

For the case with a reflector plane (elevation plane) there’s no radiation behind this plane. Is it true?

If the reflector plane is of infinite extent, then that is true.

Real reflectors have edges, so some signal will flow in the edge of the reflector. That will result in some signal being radiated behind the reflector.
https://en.wikipedia.org/wiki/Diffraction#"Knife_edge"