how to increase the gain of the microstrip patch antenna array in ADS

hi i ve designed 4X4 microstrip patch array antenna at 35GHZ using ADS
the parameters i m getting are
returnloss =-25.86
directivity is 18.56 dbi
gain= 11.23dbi
gain is very low

so i want to ask that what is the range of the gain and how can i increase the gain my antenna
plz guide me

Its a 4x4 microstrip patch array?

The gain and directivity sound decent then... what is the individual element gain?

The directivity seems ok: for a single patch, you can expect ~6 dBi. When doubling the number of elements, the directivity increases by 3dB. For 16 antennas, you can expect 6 dBi + 4*3dB = 18dBi directivity. That agrees with your simulation results.

The difference between directivity and gain is the loss in your antenna. At some point, when you add more elements, the additional loss in the distribution network is eating up all the extra gain.

Have you tried to simulate the insertion loss of your distribution (feed) network, so that you know the loss between the common input and the 16 antenna inputs?