No abstract

No 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.

This paper presents a new concept of modulated metasurface (MTS) antenna for satellite communications. As opposed to using cylindrical surface waves (SW) to excite circular apertures, we employ a quasi-optical beamformer to launch a plane SW. This architecture enables an efficient illumination of rectangular apertures. In addition, the use of anisotropic MTS elements allows us to obtain circularly-polarized beams with excellent characteristics in terms of cross-polarization discrimination. We present the design process of a prototype at K-band and the obtained simulation results, which prove the suitability of this antenna for satellite data links.

This paper presents a metasurface (MTS) beamformer based on Reflecting Luneburg Lenses (RLLs) operating in the sub-THz range. RLLs consist of two circular parallel plate waveguides (PPWs) vertically stacked. The bottom wall of the lower PPW is loaded with a MTS with an axially symmetric modulation. The wave launched by a primary feed in the bottom PPW is collimated in the top one, so that a plane wave is identically generated for any azimuthal position of the source. The proposed solution uses a bed of nails, wellsuited to fabrication by Si micromachining, to implement the RLL refractive index profile. Simulation results yield a 30% -3dB directivity bandwidth around the center frequency (280 GHz). This device can be used as a beam-former for multi-beam antennas for Earth observation or for front-and back-hauling in beyond 5G wireless.