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What sort of array is it ? When you look at the Balanis's book, you will see that if the distance between the patch is more than one half wavelength, the pattern of the array has more sidelobe but the main lobe is more directive. So if you want to minimize the sidelobe, you have to optimize the distance between them. In layout ADS, you can't put any parameters or do any optimization, you can only simulate step by step your array.
It seem to me that your gain is a little bit high for the main lobe. Perhaps an simulation error ?
THe gain for your first sidelobe is high too. Normaly, a patch antenna alone has a gain of about 6 dB. The array of 4 patch add a gain of 6 dB so your main lobe must have a gain of 12 dB.
What sort of patch (rectangular, circular ...) do you use and what is your dielectric properties ?
Moreover your spacing is too high, with a distance of 9 lambda you must have more than one sidelobe but a gain of the mainlobe important.
Try to decrease your distance between elements ....
you have essentially an array of two elements, the firs side lobe you see is the grating lobe, sorry you cannot do anything to reduce it, just try to keep the element closest to taper such grating lobe with the element factor.