Abstract-A novel type of leaky wave antenna is presented. Differently from previously reported leaky wave antennas, it is based on a radiation phenomenon which is intrinsically wide band. The antenna is designed to be an integrated receiver that is compatible with manufacturing technologies in the sub-mm wave ranges. However in order to provide a preliminary proof of concept two scaled models have been designed, manufactured and tested. One is broad band with operational frequencies between 10 and 20 GHz. The second is dual band operating at 10.5 GHz and 22.5 GHz with 43% and 19% bandwidths. The measurements are in very good agreement with the expectations, demonstrating the potentials of the leaky lens concept to realize integrated transmitters or receivers that are extremely broad band and directive. The ranges of applications are not restricted to sub-mm wave operations for which it was conceived. A joint TNO-ESTEC patent is pending on this type of antennas.