Feeds for antenna arrays

[vdbhope]

I am designing an antenna array for base stations. I want to read more about the feeding techniques that are used in arrays. I read somewhere about chebyshev and dolph-chebyshev feeds to reduce the side lobe levels. How to decide which feeding technique is best?

 

[vfone]

I think you refer to this paper:

http://jcsce.vnu.edu.vn/index.php/jcsce/article/download/157/70

The paper don't show any measurements results, only theory vs simulation results.
From my experience with array feeding networks I have doubts that this approach will work well in real life.
Especially vs frequency, because most of the arrays are not narrowband.

Grating lobes occur when the spacing between array antenna elements are large enough to permit in-phase addition of radiated fields in more than one direction.
Here are few proven approaches how to reduce the array grating lobes.
- Making the element spacing equal (or less) than λ/2 will ensure low grating lobes for any scan angle.
- Grating lobes may be reduced by applying an amplitude taper over the array (drive the outer elements with lower amplitude power).
- The antenna pattern of an antenna element (which forms the array) may reduce the grating lobes of the array to acceptable levels.
Most of the array designers do not spend much time on optimizing the performance of a single antenna element, part of the array. You could be better mathematician than Chebyshev, but if the performance of the antenna elements (each of them) is poor, the performances of the entire array will be poor.

 

[vdbhope]

I think you refer to this paper:

http://jcsce.vnu.edu.vn/index.php/jcsce/article/download/157/70

The paper don't show any measurements results, only theory vs simulation results.
From my experience with array feeding networks I have doubts that this approach will work well in real life.
Especially vs frequency, because most of the arrays are not narrowband.

Grating lobes occur when the spacing between array antenna elements are large enough to permit in-phase addition of radiated fields in more than one direction.
Here are few proven approaches how to reduce the array grating lobes.
- Making the element spacing equal (or less) than λ/2 will ensure low grating lobes for any scan angle.
- Grating lobes may be reduced by applying an amplitude taper over the array (drive the outer elements with lower amplitude power).
- The antenna pattern of an antenna element (which forms the array) may reduce the grating lobes of the array to acceptable levels.
Most of the array designers do not spend much time on optimizing the performance of a single antenna element, part of the array. You could be better mathematician than Chebyshev, but if the performance of the antenna elements (each of them) is poor, the performances of the entire array will be poor.

Thanks a lot for the explanation. I have a question though, why do you say that array designers do not spend time on optimizing a single antenna? In the end, the array performance is going to depend on the single element as well.

 

[vfone]

Most of the multi-element antenna array designers are algorithm engineers or mathematicians, with very basic (or not at all) antenna design or RF design knowledge. No offense for them, but this is the reality..
Unfortunatelly you cannot separate the single antenna element development from the entire array development.

 

[vdbhope]

Most of the multi-element antenna array designers are algorithm engineers or mathematicians, with very basic (or not at all) antenna design or RF design knowledge. No offense for them, but this is the reality..
Unfortunatelly you cannot separate the single antenna element development from the entire array development.

That is unfortunate. I am an RF engineer though. So, I can't help but focus on the single element as well.
I have been reading about feeding techniques. Seems like you can do a lot of improvement on side lobe levels by just scaling the excitation amplitude to be lower for extreme elements. The thing I am struggling with is front to back ratio of the single element and also the array. Do you have any suggestion or references on how to reduce the back lobe?