Discrete Dielectric Reflectarray and Lens for E-Band With Different Feed

This letter presents the design and results of low-loss discrete dielectric flat reflectarray and lens for E-band. Using two different kinds of feed, 3-D-pyramidal (wideband) horn and 2 2 planar microstrip array (narrowband) antenna, the radiation performances of the two collimating structures are investigated. The discrete lens is optimized to cover the frequencies 71-86 GHz (71-76- and 81-86-GHz bands), while the discrete reflectarray is optimized to cover the 71-76-GHz band. The presented designs utilize the principle of perforated dielectric substrate using a square lattice of drilled holes of different radii and can be fabricated using standard printed circuit board (PCB) technology. The discrete lens has 41 x 41 unit cells and thickness of 6.35 mm, while the reflectarray has 40 x 40 unit cells and thickness of 3.24 mm. A good impedance matching (vertical bar S-11 vertical bar < -10 dB) and peak gain of 34 +/- 1 dB with maximum aperture efficiency of 44.6% are achieved over 71-86 GHz for the lens case. On the other hand, reflectarray with peak gain of 32 +/- 1 dB and aperture efficiency of 41.9% are achieved for 71-76-GHz band.