In this work, a compact patch antenna based on a low temperature cofired ceramic (LTCC) has been presented for V-band system-on-package (SoP) applications. In order to integrate it with transceiver block, a waveguide (W/G) to embedded microstrip line (eMSL) vertical transition was designed using slot-fed double stacked patch antennas for easy assembly and wide bandwidth. The $2{ imes}2$ patch antenna integrating the transition was designed and fabricated in the 5-layer LTCC dielectrics. The whole size of the fabricated antenna including the $2{ imes}2$ patches, transition and W/G was $20{ imes}24{ imes}5.39mm^3$. The fabricated antenna has achieved a 10 dB impedance bandwidth of 2.45 GHz from 61 to 63.45 GHz.