Design of non-dimensional parameters in stretchable microstrip antennas with coupled mechanics-electromagnetics

With the rapid development of flexible/stretchable electronics, wireless technology for wearable systems starts to gain momentum. Here, a class of stretchable microstrip antennas composed of serpentine mesh layouts in both the patch and ground plane is designed. The study of the representative stretchable microstrip antenna reveals the effects of the geometric parameters on its electromagnetic properties. Although the non-dimensional parameters have been shown to uniquely determine the mechanical properties of the serpentine mesh structure, their influence on the coupled mechanical-electromagnetic properties is different in the stretchable antenna. This study systematically reveals the effects of the non-dimensional parameters at various tensile strain levels from the coupled mechanics-electromagnetics simulations, with experimental validations. The mechanical stretchability of the serpentine mesh structure increases as the arc angle increases or the normalized width (i.e., the ratio of the width to radius) decreases. The normalized width together with the change in radius and width provides an effective means to tune the initial resonance frequency, impedance matching, and radiation pattern of the stretchable antenna without altering the strain sensitivity. Additionally, the advanced laser micromachining technology for the manufacturing of the stretchable microstrip antenna can also be explored to the other stretchable microwave devices.