FD-TD analysis of dielectric rod antennas with an antireflective layer

Dielectric rod antennas have been known many years as an endfire radiator. Experimental studies have been conducted at microwave frequencies and also at millimeter-wave frequencies. Despite the extensive use of these antennas, no exact design procedure exists for them. We analyze dielectric rod antennas fed by a metallic rectangular waveguide using the FD-TD method. Special attention is paid to reduction in the reflected wave from the free end. For this, an antireflective (AR) layer, which is well-known in photonics applications, is introduced. The radiation pattern and the gain are evaluated and discussed.