Considerations on size reduction of UWB antennas

To successfully reduce the size of UWB antennas requires a good understanding of radiation mechanisms, impedance behaviour, acceptable trade-off between gain and bandwidth and effective methods to reduce phase near-field velocity. The fact that theoretical limitation of a small antenna is determined by the antenna´s size in terms of free-space wavelength regardless of the geometry or composition the antenna should also be acknowledged. Our current finding seems to indicate, inductive loading is more advantageous over capacitive loading due to the increase of antenna impedance associated with this treatment.