how to optimize antenna for the desired directivity

in CST we can parametrize our structure and then can perform parametrization and from the results of parametrization we can optimize of our structure.
e.g for the desired S11

however i want to optimize the directivity of my antenna .

is it possible to do in CST and if answer is yes whats the procedure to do it

any suggestions, comments or links would be welcome

regards

I have no idea about CST.

But Directivity is dependent on Gain which is dependent on Aperature Area and Efficiency.

well thanks for your comments but i think you havent read my question carefully

i know directivity, gain and efficiency are all related to each other

my question was how we can use 3D EM simulatior ( CST MWS) to optimize the directivity of any antenna .

regards

hi Shahid78,
To optimize an antenna structure for any purpose, such as: Gain, Bandwidth, beamwidth..., I think first you should find out which parameters can strongly effect to your desired characteristic like parasitic elements, radiation element configuration... , for instance. Then you can use those parameters as the variables for optimization progress.

Regards!

There are only a few parameters you are able to change in any single design and most of them will just change the frequency not the directivity. One thing you should vary is if it is cavity backed change the distance of the cavity usually something << lambda should work good.

Directivity is all about the type of antenna you are using, you cannot just change a dielectric and change the directivity.

I recommend you decided first on how much gain / directivity you want, then post back here and I will reccomend an antenna type then you can adjust the antenna type for the frequency you want it at in the EM program.

Hope this helps,
Zach

well i am looking for 12dBi directivity. and enfire radiation pattern

i am working on yagi . so if you have any other idea or tell me which parameters of yagi will most affect the directivity that will be great

regards

I would recommend a helix for that

Added after 1 minutes:

Sorry I did not quite finish that, I would recommend a helix with at least 4 turns it is very easy to match and is very broad band and is an end fire design. it is CP I hope that is alright, if that is not what you are looking for let me know

In a yagi the number of directors has a strong effect on the gain. Longer yagi's usually have more gain is another way to view the situation.

A dipole with a corner reflector could easily get you to 12 dBi. That might be easier. A relatively small horn would work too.

When you talk about gain of an antenna the two major contributors are frequency and antenna size. Without that information the responses you get are WAG's. The world wants high gain, wide field of view, small (and cheap) antennas at any frequency. This is often very frustrating. Good Luck.

i want to design a cvity backed antenna in x-band with low cross-pol, 3dB BW > 120 deg and freq BW >1 GHz
Can anybody help