A transmission line circuit-oriented approach for miniaturization of a log-periodic dipole array (LPDA) antenna

A miniaturized planar log-periodic dipole array (LPDA) antenna is presented. Antenna miniaturization is accomplished by replacing the uniform dipole elements of the conventional LPDA antenna with elements that possess variable-impedance profiles governed by a truncated Fourier series. Conventional and miniaturized LPDA antennas exhibiting 7 dB end-fire gains are designed to operate over the frequency range of 2 to 4 GHz. A 32 % reduction in dipole arm length was achieved. Full-wave simulation results show stable directional radiation patterns, excellent front-to-back ratio over the designed impedance bandwidth, and minimal degradation in the overall electrical performance.