3-D Printed Flexible Heterogeneous Substrates with Customizable Gain and Bandwidth

This paper presents a 3-D printed flexible heterogeneous substrate for wearable antennas with customizable bandwidth and gain. These performance parameters are modified by varying the ratio of percentage area of Acrylonitrile Butadiene Styrene (ABS) to NinjaFlex. Five flexible 3-D printed microstrip patch antenna (MPA) prototypes are designed, realized and measured each with different percentage area ratios, where the MPA's RF performance is characterized with curvature. The five substrate designs are based on a combination of rigid ABS tiles of triangular shape surrounded with flexible NinjaFlex. All five designs show minimal antenna sensitivity to curvature, with a minimum resonant frequency shift of less than 1.2%. Results closely agree with simulations. Increasing the ABS area increases the MPA's gain, but reduces the bandwidth and increases substrate rigidity. This results in a highly customizable and cost-effective substrate that allows the antenna designer flexibility in the choice of design parameters.