This letter studies the frequency- and time-domain
performance of a recently developed printed coplanar-fed ultrawideband
(UWB) monopole antenna aiming at predicting its
behavior close to a human arm. The input reflection coefficient and fidelity factor of the antenna were evaluated in free
space and close to an arm. Simulations using three simplified
arm models with different cross sections (flat, rectangular, and
elliptical) were compared to measurements. All models include
the relevant human tissue layers: skin, fat, muscle, and bone. It
was found that an accurate model requires the inclusion of the
tissues broadband dispersion characterization. Moreover, the
skin layer has a major impact in |S11|, and a small effect on
fidelity, while the models can be simplified by discarding the bone.
Furthermore, the geometry of the models is less relevant than
dispersion characterization. It has also been observed that using
the simplified models with proper broadband tissues dispersion
yields good performance predictions, and that the fidelity factor
increases as the antenna gets closer to the arm.