A log-periodic dipole antenna employing a forward-firing feed mechanism for pulse radiation

It has long been recognized that LPDAs (log-periodic dipole antennas) exhibit dispersive behavior due to the reverse-firing feed mechanism. In this paper, it is shown numerically that an LPDA incorporating an end-fire or forward-firing feed mechanism can reproduce time domain pulses accurately. It appears to be necessary to incorporate an absorbing load at the high-frequency end of the array in order to obtain the best behavior. However, the load absorbs only a small amount of the input power and thus the design can exhibit comparable gain to a traditional LPDA, It is also shown that it is possible to effectively discriminate against the presence of a second active region with lumped resistive loading.