Gain enhancement of printed log-periodic dipole array antenna using director cell

In this communication, several parasitic dipole elements served as director cell are added to the shorter end of the printed Log-periodic dipole array (PLPDA) antenna for the gain enhancement. This novel antenna is based on the combination of the PLPDA antenna and the quasi-Yagi antenna techniques, so called printed Log-Yagi dipole array antenna (PLYDA). The number and the distribution of the director cell are discussed and optimized. A prototype PLYDA antenna fed by half mode substrate integrated waveguide (HMSIW) is manufactured, as well as a HMSIW PLPDA antenna for comparison. The return loss and far-field radiation patterns were measured and presented in this work. The proposed PLYDA antenna exhibits gain enhancement of 0.2-2 dB in comparison with the equal size PLPDA antenna over the operating frequency range 21-40 GHz. The simulated and measured results are in good agreement, and the gain enhancement using the director cell is verified.