A Multi-Point Feeding Stub-Loaded Dipole with 10 f₀ Out-of-Band Harmonic Suppression

A dipole antenna with ultrawideband harmonic suppression is proposed in this communication using multi-point feeding and stub-loaded technology. Two stubs are loaded for tuning the current nulls of the fifth and third modes to coincide. 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 .