How can I reduce the beamwidth of a patch antenna array (series feed network)?

[doanphilong]

How can I reduce the beamwidth of patch antenna array (series feed network ) ?

Dear all,
I'm designing a patch antenna array with series feed network and I want to reduce the beamwidth but I don't know how to do that. Its beamwidth now is 26.9 degrees and I want it at 20 degrees.
Please help me, any suggestion will be appreciate. Thank you

 

[Terminator3]

Re: How can I reduce the beamwidth of patch antenna array (series feed network ) ?

First of all you must vary distance between patches. You can make narrower main beam, but side beams will be here too. You can vary patch sizes or use tapers. Google on tapered series feeding.
There is a formula, array factor, https://www.antenna-theory.com/arrays/arrayfactor.php
Altering distance between patches and power distribution (T-dividers) you can control beam and side-beams.
Problem with varying patch sizes it is difficult to design (my opinion).
Tapers are easy to design.
Which type of series feedback do you use? There is two types
1. feeding line from both sides of patch, goes through all patches
2. long line with many tapers and T-dividers to each patch.
First one is more difficult to make with low side-lobes, because power distribution of last patches in series
Second one is widely used today. You can increase number of patches, if your substrate have stable Er, then you can get very narrow beam.

 

[doanphilong]

Re: How can I reduce the beamwidth of patch antenna array (series feed network ) ?

First of all you must vary distance between patches. You can make narrower main beam, but side beams will be here too. You can vary patch sizes or use tapers. Google on tapered series feeding.
There is a formula, array factor, https://www.antenna-theory.com/arrays/arrayfactor.php
Altering distance between patches and power distribution (T-dividers) you can control beam and side-beams.
Problem with varying patch sizes it is difficult to design (my opinion).
Tapers are easy to design.
Which type of series feedback do you use? There is two types
1. feeding line from both sides of patch, goes through all patches
2. long line with many tapers and T-dividers to each patch.
First one is more difficult to make with low side-lobes, because power distribution of last patches in series
Second one is widely used today. You can increase number of patches, if your substrate have stable Er, then you can get very narrow beam.

thank you. this is my design, is it tapered series feeding ?

https://obrazki.elektroda.pl/4038376300_1461670151.png

 

[Terminator3]

Re: How can I reduce the beamwidth of patch antenna array (series feed network ) ?

Yours is true series feeding.
search in yahoo.com for "A Novel Series-Fed Taper Antenna Array Design" for optimizations
You can try do similar thing, make input impedance of patches different, and their sizes too, so central patch radiates more power.

There is also parallel-series feeding:
**broken link removed**
one long row is parallel series feeding.

And third type is corporate feeding patch array.

Also there are many combinations. Corporate feeding with series feeding blocks, etc..

So why you do not add more patches? I think in CST you also can learn some advanced options, like optimizations. Many simulation software have "optimization goals". So you can make all sizes variable and make CST search for best configuration with narrow beam optimization goal. Although i never tried CST.
But even in free QUCS simulator you can make parameter SWEEP. CST surely can do it too. So you can make some sizes variable, and do parameter SWEEP, and build chart on how beam-width depends on your sweep parameter.