Fig.2. The antenna
is fed with 50 Ω microstrip line (d×dfeed) and
printed on the FR4 substrate (Lsub×Wsub) with the
height (h) of 1.5 mm and relative permittivity
r ε =3.5. The ground plane has the dimension of
(Wsub×Lg) so that ultra wideband characteristic is
attained. To avoid the interference, the strip bar
with the dimension of Ws×Ls is located in the
square ring (outer: L and inner: Ln).