An independently fed log-periodic antenna for directed pulsed radiation

The development of an antenna capable of radiating a band-limited pulse with minimal distortion, negligible loss, and significant directivity is reported. A design was derived by modification of the conventional log-periodic dipole array to permit independent feeding of each dipole. This was modeled with a time-domain integral equation program and iterated to find a design that minimized phase dispersion across the operating band. The optimal design was realized in hardware, using a printed structure to feed the dipoles independently; this was located in the normal plane to prevent distortion of the radiated fields. When tested, the antenna was found to give a good quality radiated pulse in the main beam direction, with weaker and dispersed waveforms in other directions, indicating significant directive gain.