Physics

Lens (geology)

Fresnel equations

Fresnel number

Fresnel lens

Terahertz radiation

Optics

Slot antenna

Metamaterial

Radiation pattern

Diffraction

Antenna (radio)

Materials science

Computer science

Fresnel zone antenna

Zone plate

Refractive index

Optoelectronics

Telecommunications

IEEE Transactions on Antennas and Propagation

In this paper, a novel 3-D printed circularly polarized (CP) modified Fresnel lens antenna operating at 300 GHz is introduced. By virtue of the superior geometric flexibility of the 3-D printing technique, a modified Fresnel lens consisting of subwavelength discrete dielectric posts in the odd-numbered Fresnel zones is proposed. It is further demonstrated that by integrating dielectric anisotropic metamaterial, the modified Fresnel lens can realize CP radiation fed by a simple linearly polarized (LP) open-ended waveguide (OEWG). The 3-D printing approach is also investigated to push the performance envelops of the 3-D printer for realization of the terahertz CP lens. The measured results show that the axial ratios (ARs) of the fabricated antenna prototype are smaller than 3 dB from 265 to 320 GHz. Moreover, the modified Fresnel lens has a maximum gain of 27.4 dBic, which is 0.9 dB larger than that of the conventional Fresnel zone plane antenna (FZPA). These validate the concept, the design, and the fabricated prototype.

3-D Printed Circularly Polarized Modified Fresnel Lens Operating at Terahertz Frequencies