Wideband 3D-Printed Cylindrical DRAs Exploiting Customizable Permittivity Variation in Radial Direction

One of the main constraints in designing RF devices that leverage on the use of multiple materials with different permittivity is related to the physical properties of the materials available for the realization. Often, the optimal design is sacrificed in the name of feasibility. In this work, a new method for tailoring the effective permittivity of a substrate for realizing DRA is presented. The method is tested with the designing and realization of an ultra-wideband Cylindrical DRA (CDRA) which exploits the well-known technique of applying stacked layers of materials with different permittivity to achieve a bandwidth improvement. Specifically, a CDRA, fed with a coaxial probe and operating between 3.45 GHz and 6.45 GHz, has been designed, realized, and tested exhibiting very good agreement with the simulations. If compared with the traditional one, the new design is more feasible, cost-effective, and customizable to tailor virtually any value of electrical permittivity smaller than that of the bulk material.