A 76GHz phased array antenna using a waffle-iron ridge waveguide with a non-metal contact structure has been developed. The structure has the advantages of avoiding losses due to imperfect metal contact and facilitating the construction of small-size multi-layer stacked structures. The principle of a 16-column phased array antenna with a size of 62mm× 62mm× 25mm is presented. It is shown that the phase difference between all adjacent radiators in the phased array is the same, confirming the validity of the fundamental operation of the antenna.