Small ultra wideband antenna having unidirectional radiation pattern

An ultra wideband (UWB) antenna comprising:

• a substrate;
• a power feeding part which is provided on a surface of the substrate and receives an external electromagnetic energy;
• a dipole radiator which is excited by the electromagnetic energy fed through the power feeding part and radiates electromagnetic waves;
• an active loop radiator which makes the electromagnetic waves radiated by the dipole radiator have a unidirectional radiation pattern by interfering the electromagnetic waves, and
• at least one passive loop radiator which is excited by the electromagnetic energy induced by the dipole radiator and the active loop radiator, and radiates the electromagnetic energy in an omnidirectional pattern,
• wherein the power feeding part comprises:
• a signal terminal which is provided on the surface of the substrate and receives the electromagnetic energy;
• and
• first and second ground terminals arranged on one and the other sides of the signal terminal, respectively, to form a coplanar waveguide structure on the surface of the substrate.