Parallel-plate slot antenna with a planar left-handed lens for TEM plane wave excitation at 7.5 GHz

In this paper, a planar lens fabricated with LH metamaterials is proposed as a new feeding form to generate a TEM mode in parallel-plate slot antennas enhancing her radiation efficiency. The LH lens is faced to a RH medium through a parabolic interface that allows exciting a cylindrical wave from the focus lens, using a coaxial probe, which is transformed in a plane wave due to the negative refraction effect between the LH and the RH medium interface, as it has already been demonstrated. To avoid further reflections both mediums should present the same electromagnetic densities, i.e., the same refractive index with opposite sign (n_RH =-n_LH). To manufacture a planar lens as a LH medium has been proposed the "mushroom" structure . Main advantages of this kind of materials are its low cost and the simplicity of fabrication through planar technology. In figure 1 can be seen the mushroom structure and a diagram with the LH lens exciting the parallel plate slot antenna.