This paper presents a truly integrated antennas in mm and sub-mm wave regimes can be realized by printing planar radiating elements in the focal plane of elliptical or extended hemispherical lens antennas. The elliptical shape of the lens gives high focusing properties provided that its eccentricity is properly related to its dielectric constant (e=1/epsiv1/2 r). In the frame of cooperation activity between TNO and SRON, the main purpose of this contribution is to present a new way to increase the directivity of the focal plane feeds typically used to excite such lenses. The driving reason for this effort is the desire to diminish the impact of the reflections at the dielectric air interface when these structures are proposed as focal plane...