Study of Electrical and Mechanical Characteristics of Inkjet-Printed Patch Antenna under Uniaxial and Biaxial Bending

This paper discusses the electrical and mechanical characterization of an inkjet-printed patch antenna under uniaxial and biaxial bending. A 30 mm x 40 mm patch antenna design with a truncated copper ground plane was designed and fabricated by inkjet printing on a polyethylene terephthalate (PET) substrate. The fabricated antenna samples were then fixtured on cylindrical polycarbonate mandrels as well as on 3D printed saddle-like structures using polylactic acid (PLA). S-11 was measured in both bent and flat configurations, and a shift in resonant frequency was observed. A maximum decrease of about 12.6% in resonant frequency under cylindrical bending was observed, and this decrease can be attributed to the decrease in conductance in the printed components due to small radius of some of the mandrels and due to sequential repetitive bending. The change in resonant frequency under biaxial saddle-like bending was small due to larger radii of the saddle-like surfaces and due to one-time bending. Electrical simulations in ANSYS (TM) HFSS were carried out to determine S-11 of the patch antenna under flat configuration and was compared favorably against experimental data. Mechanical finite-element models in ANSYS (TM) Workbench were carried out to determine the strain distribution under both uniaxial and biaxial bending. A maximum strain of 0.0169 under uniaxial bending and 0.0029 under biaxial bending was observed.