A 3D-printed Lens Antenna with Tunable Varifocal Based on the Moiré Effect

In this letter, a novel millimeter-wave (MMW) lens antenna (LA) using Moiré dielectric lenses (MDLs) based on the Moiré effect is proposed. The MDLs operate at 94 GHz , composed of two phase-complementary dielectric lenses. They facilitate different focal lengths of Fresnel lens phase distribution through the rotation of lenses, thereby enabling continuously adjusted focal lengths. The dielectric element, a simple rectangular dielectric post with a square hole, achieves a 360° linear transmission phase by altering the height of the pillars. Photocuring three-dimensional (3D) printing was used to illustrate the potential of lens antennas with constantly changeable focal lengths. Simulations demonstrate the reflection coefficient of the MDLs antenna in the W-band is below -20 dB. At 94 GHz, the focal length can be continuously adjusted from 46 mm to 186 mm. The measured results match the theoretical and predicted values rather well. According to the measured result, the power density can grow up to a maximum of 6 dB at the focus. The MDLs proposed in this letter have the advantages of simple design and low cost, offering new possibilities for further near-field focusing (NFF) antenna systems.