A Multipoint Feeding Stub-Loaded Dipole With 10f₀ Out-of-Band Harmonic Suppression

A dipole antenna with ultrawideband harmonic suppression is proposed in this communication using multipoint feeding and stub-loaded technology. Two stubs are loaded for tuning the current nulls of the fifth and third modes to coincide and then use the shared current nulls of the third- and fifth-order modes as feeding points to suppress them concurrently. The seventh- and ninth-order modes are suppressed by loading parallel stubs acting as open-circuited transmission lines with short lengths. A prototype is designed to validate the design idea. The measurements show that the antenna operates at the center frequency
$f_{0}$
of 1.2 GHz, and the ultrawideband out-of-band harmonic suppression reaches 10
$f_{0}$
.