Fully Metallic Luneburg Metalens Antenna in Gap Waveguide Technology at V-Band

Abstract

This paper presents the design of a flat Luneburg metalens antenna at V-band using Gap Waveguide (GW) technology. The metalens consists of a parallel plate waveguide loaded with metallic pins whose height is modulated to get an effective refractive index that follows the Luneburg equation. A Groove Gap Waveguide (GGW) H-plane horn is used to illuminate the metalens, such that the rays are collimated and a planar wavefront is generated in the direction of propagation. Since the structure at hand is planar, it can be efficiently integrated on flat surfaces. Moreover, the fully metallic structure is mechanically robust and presents lower losses than lenses including dielectric substrates. A prototype has been fabricated and tested, simulations and experimental results are in very good agreement. The metalens yields an input reflection coefficient (S11) below -10 dB from 45 to 70 GHz, whereas the -3dB gain fractional bandwidth is 26.2% with respect to a center frequency of 60 GHz, with a peak of 22.5 dB at 61 GHz. These features make this design an interesting solution for millimeter-wave applications.

Alumina 3-D Printed Wide-Angle Partial Maxwell Fish-Eye Lens Antenna

“…Typical representations of wide-angle lenses are Luneburg lenses [9], Gutman lenses [10]- [11], Maxwell Fish-Eye lenses (MFE) [12]- [16], Eaton lenses [17]- [18], or geodesic lenses [19]. Fabrication techniques for the aforementioned lenses vary from a full metallic implementation (bed-of-nails [20], groove gap waveguide [21], parallel plate waveguide [21]) to the lens realization using dielectric materials (3D printing [23], mechanical or chemical micromachining [5], substrate integrated waveguides [1]).…”

Investigation of Gliding Walled Multilayer Waveguides

“…The initial designs involved the use of EBGs, which required at least two rows of pins along the transmission line paths to minimize electromagnetic field leakage. Many devices and mmWave components were manufactured utilizing these pin-based unit cells, such as bandpass filters [8], D-band slot antenna array [9], horn antennas [10], Luneburg antennas [11], and other gap waveguide-based components [12][13][14][15][16][17][18]. However, as mentioned in [7], the disadvantage of manufacturing these nails or pins was the complexity of producing them on the mm and µm scale.…”

Evaluation of Losses in 3-D-Printed Geodesic Lenses Using a Ray-Tracing Model

“…An alternative is planar Luneburg lens antennas, which can be made with discretized layers of dielectrics [10] or metasurfaces [11]- [13]. To avoid losses due to propagation in dielectric materials in the mmwave range, fully metallic metasurfaces are preferred [14]- [16]. However, at high frequencies, the subwavelength size of these metasurfaces makes their manufacture challenging.…”