Heterogeneous approach of substrate for antenna in package is proposed in this paper. The objective is to maintain a typical SiP manufacturing process, while forge the antenna performance by using novel material. The bonding of such a heterogeneous substrate is shown to maintain critical stacked through via into the antenna layers. The RF performance of AiP manufactured with this approach is characterized, and is shown to be excellent for antenna in the mmWave range. This substrate is demonstrated with mitigated warpage, and can pass stringent reliability requirement.