Many, if not most small device integrated antenna designs are based on derivatives of the well known planar inverted-F
antenna or PIFA. The small, single resonant PIFA is a straight-forward design, derived from the transition of a
straight-wire monopole into an inverted-L antenna or ILA (for height reduction), then into an inverted-F antenna or IFA
(for impedance matching) and finally, into a PIFA for increased operating bandwidth. From the perspective of input
impedance and bandwidth, the ILA [1] is a reduced height monopole with correspondingly decreased resonant
resistance and bandwidth. The IFA [1] is a parallel stub matched Inverted-L and the PIFA is an IFA with increased
conductor volume, which allows for increased operating bandwidth and increased flexibility in terms of achieving
multiband operation