An aperture coupled feeding technique based dual band high gain 4 × 4 microstrip antenna array has been presented here for X-band radar and satellite communication. The designed array consists of three layers which are corporate feed network, 2D array of radiating patches, and coupling apertures on the ground plane. The novelty of the work is the designing of a new asymmetric H-shaped slot for the aperture coupled antenna (ACA) element. The antenna exhibits dual resonances in X-band at frequencies 8.45 and 11.15 GHz, those are altered by changing ACA's physical dimensions. The three layers of the array are printed on two Taconic TLY-5 dielectric materials, which are stacked over each other. The designed array is realized on overall size of 100×100×2.09 mm3 and having return loss bandwidth (BW) of 3.2 % in both bands that covers frequencies 8.53 to 8.81 GHz and 10.8 to 11.15 GHz. In two bands array radiates with gain of 17.1 and 19.34 dBi, and efficiencies of 90.7 % and 94.1 % respectively. The array exhibits considerable low cross-polarization of < - 14.2 dB and <- 36.2 dB at two operating frequencies. © 2023 IEEE.