More and more applications require small conformal ultra-wide bandwidth (UWB) antenna designs. The radiation performance of such antennas faces fundamental limitations imposing on impedance, gain and bandwidth. Antenna miniaturization can be achieved by slowing down the currents and fields propagating along antenna arms. Convention approaches involve the utilization of dielectric loading or meandered arms. The former increases the shunt capacitance and the later increases the serial inductance. Either approach decreases the wavelength of local currents (or fields) on antenna, thus achieving resonance at a smaller physical size. This paper discusses such miniaturization techniques and their relationship with fundamental limitations.
