Flexible 3-D printed substrates for antenna applications

Consumer demand for small devices with wireless connectivity has put increasing pressure on antenna engineers to improve electromagnetic performance in smaller packages. These design constraints are further exacerbated by increasing demand for improved bandwidth, efficiency and frequency coverage. Including an additional degree of design freedom by manipulating the substrate shape and properties can help address these challenges. This paper critically reviews the electromagnetic advantages of altering the dielectric substrate section of the antenna as opposed to the conducting elements. Changing the dielectric has been used to improve the bandwidth, efficiency and gain of antennas. Heterogeneous substrates have also been employed to lower the effective permittivity, suppress surface waves for high indexed substrate materials and reduce mutual coupling. These synthetic substrates are very difficult to manufacture using conventional technologies. Complex 3-D printed geometries can easily be manufactured from computer aided design models that can be exported directly from electromagnetic simulation software. 3-D printing allows the geometry to be varied in all three dimensions, therefore printed cavities of various shapes and sizes can lead to a smooth or discrete change in the effective permittivity. With the latest advances in additive manufacturing and 3-D printing, the antenna and radiofrequency designer will be able to control the local effective permittivity and the substrate shape to gain electromagnetic advantages.