The quantitative assessment of the UWB performance of log-periodic dipole antennas with fixed equalization

Antennas for ultra-wideband applications have traditionally included TEM horns, resistively loaded monopoles and dipoles, and tapered dipoles, all of which satisfy, to some extent, the distortionless transmission criterion. Despite their broadband performance, log-periodic dipole antennas have not been exploited because of their well-known dispersive characteristics. These dispersive characteristics cause such antennas to have very long impulse responses. Here, however, using a correlation integral, we compute a quantity that we believe is most indicative of UWB performance: the correlation between an appropriate template waveform and the electric field radiated from a pulse-excited antenna. We show that the correlated energy pattern of an LPDA is almost identical to the energy pattern, thus indicating the efficacy that can be provided by employing a matched filter. The performance of an equalized LPDA is numerically predicted and compared with previous work in which a modified, forward-firing, non-dispersive LPDA design was proposed (McLean, J.S. and Sutton, R., Proc. IEEE Intl. Symp. on Antennas and Prop., 2003).