Abstract: A vertically stacked array antenna structure is described. The structure comprises a radiating layer, a passive layer disposed under said radiating layer, an active layer disposed under said passive layer, and an interface assembly. The radiating layer comprises an array of radiating elements. The passive layer has only passive components. At least a part of the passive components includes an array of RF duplexers corresponding to the array of radiating elements. The active layer comprises RF amplifiers. The interface assembly comprises at least one metallic frame which is in direct thermal coupling with the RF amplifiers. The interface assembly is configured for providing thermal communication of the active layer with a heat exchanger.