Very Low Profile and Dielectric Loaded Feeder Antenna

In this letter, very low profile planar horn antenna feeders are designed and measured. Using previous results of antennas consisting of a narrow slot on a metallic plane and flanked by two grooves, a further step is given here by reducing the thickness of the prototype. A key factor in the approach is the operation in the transversal slot resonance instead of the usual longitudinal slot resonance. Moreover, by inserting a dielectric material of relative permittivity epsiv_r > 1, the thickness can be further reduced, maintaining and even improving the radiation features of the prototype. Reducing the metallic plate thickness has important consequences in the weight and profile of the antennas, making them easy to handle and to fit into different structures. In addition, in ranges where the wavelength is of the order of centimeters, a thick metallic plate can be a serious drawback due to mechanical restrictions. In these cases the design following the rules given in this letter can alleviate this constraint.