Technologies directed to embedding a calibration antenna in an antenna structure of a phased array antenna are described. The antenna structure includes a ground plane, a first antenna element, and a second antenna element. The first antenna element and the second antenna element are located in a first plane. The second antenna element is separated from the first antenna element by a first distance. Dielectric material is located between the ground plane and the first plane. The antenna structure further includes a third antenna element that is located in a second plane. The second plane is located between the ground plane and the first plane. The third antenna element is located in an area with a first dimension and a second dimension that are each less than half of the first distance.