Multiple antenna beams

yaggi

Hi all,

Is it possible to produce multiple (main) beams with antenna arrays ? If yes, please give me the reference.

Regards
svarun

antenna beams

Since I'm around, the quick anwer with ref is yes,
Definitely yes!

Just google something like 'two beam antenna array'
and you find info.

element spac

svarun:

Getting multiple beams out of an antenna array usually requires elements to be spaced apart by at least 1/2 wavelength (element phase center to phase center).

Array designers will sometimes develop antenna arrays with larger element-to-element spacing (or lattice spacing for 2D arrays) so that you get natural grating lobes in visible space. Then they will take the signals off of each element separately and use adaptive signal processing (I think they usually use digital signal processing and do the combining in a signal processor) to synthesize multiple beam directions for the purpose of focusing the array on 2 or more desired signals. In this way, they can also control and place antenna pattern nulls on noise, jammer or clutter sources in order to maximize the overall SNR.

If you have some code for antenna array pattern visualization, try an experiment where you start with either a 1D or a 2D array with center-to-center spacings of about 1/4 wavelength, and then move them apart. You should see the antenna pattern show a grating lobe at the edges of visible space (the horizon) as the elements reach 1/2 wavelength spacing.

You can also achieve multiple beams if you influence the element-to-element phase to "steer" the main beam off of boresight. This can make grating lobes (or you can think of them as extra main beams, depending on your application) appear in the visible space as well.

Good luck,

--Max

Hi Max,

Where does "visible space" start and end ?
Is it the entire space (half hemisphere) in front of the background plane ?

Also, if I have 2 main beams (very close to each other) at boresight, what do I change in the array to make them super-impose ?

Thanks alot.

yes

you mount each antenna exactly 1 lamba away from its other half

or quartets

and use a phasing harnes or gamma feed {adjustable rods much like a balun}

so you can have say a quad four element cross yaggi array

all circular polerised

using just coax measured

for referances you need to look for amature radio books from the ARRL and RSGB and study YAGGI and also helical beem antenna use keywords in google and group using ++

at the end of a line add -- to remove all the rubbish and leave only the keyword hits there is plenty on the net and i need not go find your links

its best you do and dont be so lazy to just post a lame request for help instead of looking learning then posting your findings

By references I meant , good papers. I don't need a stupid suggestion like "Google for it.". I am a responsible researcher.

I hope we will not have "google it" as an answer for our questions and as a suggestion. Otherwise, we would not have a reason to hang out in this forum.

Hi svarun

you don't need ref. run with any antenna software array with space more than λ between the elements and you will get multi beam antenna. it's just simple Physics.
more elements will give you more beams. the Ref. gain level of beams will be like Ref. gain of element pattern.

Svarun you can do it with Rotman lens also.

pl