The advancement of Internet of Things and associated
technologies
has led to the widespread usage of smart wearable devices, greatly
boosting the demand for flexible antennas, which are critical electromagnetic
components in such devices. Additive manufacturing technologies provide
a feasible solution for the creation of wearable and flexible antennas.
However, performance reliability under deformation and radiation safety
near the human body are two issues that need to be solved for such
antennas. Currently, there are few reports on compact, flexible ultrawideband
(UWB) antennas with more notch numbers, reliable bendability, and
radiation safety. In this paper, a UWB antenna with trinotched characteristics
for wearable applications was proposed and developed using printable
conductive silver materials consisting of silver microflakes or silver
nanoparticles. The antenna has a compact size of 18 × 20 ×
0.12 mm3 and adopts a gradient feeder and a radiation patch
with three folding slots. It was fabricated on transparent and flexible
poly(ethylene terephthalate) film substrates, using screen printing
and inkjet printing. The measurement results demonstrated that the
fabricated antennas could cover the UWB band (2.35–10.93 GHz)
while efficiently filtering out interferences from the C-band downlink
satellite system (3.43–4.21 GHz), wireless local area networks
(4.66–5.29 GHz), and X-band uplink satellite system (6.73–8.02
GHz), which was consistent with the simulation results. The bendability
and radiation safety of the antennas were evaluated, proving their
feasibility for usage under bending conditions and near the human
body. Additionally, it was found that the screen-printed antenna performed
better after bending. The research is expected to provide guidance
on designing flexible antennas that are both safe to wear and easily
conformable.