The design, realization, and experimental characterization of a 400-element electronically reconfigurable transmitarray operating in the Ka-band is presented. It is based on linearly polarized unit-cells with 180° phase-shifting capability. Several sequential rotation schemes have been compared numerically to generate a circularly polarized beam over a broad frequency band, and a random distribution has been selected to mitigate spurious cross-polarized side-lobes when scanning the main beam. The 2-D electronic beam-steering capabilities of ±60° have been verified experimentally. The prototype, illuminated by a horn antenna as a focal source, exhibits a broadside gain of 20.8 dBi at 29.0 GHz and a 3-dB bandwidth of 14.6% with radiation efficiency of 58%. The axial ratio remains below 2 dB within this bandwidth. Next, a planar substrate integrated waveguide focal source array was designed in order to reduce the focal distance by about 50% and thereby significantly improve the antenna compactness, and similar radiation performance is demonstrated numerically and experimentally.

This paper presents the design, optimization, fabrication, and characterization of an electronically steerable transmitarray with 2 bits of phase quantization per unit cell. The proposed transmitarray operates in linear polarization at Ka-band and is composed of 14W14 reconfigurable unit-cells. Four p-i-n diodes are integrated on each unit-cell to control the radiated field phase distribution across the transmitarray aperture. The prototype demonstrates experimentally pencil beam scanning over a 120W120-degree window, a maximum gain at broadside of 19.8 dBi, and a 3-dB fractional bandwidth of 16.2%.

Dual-band transmitarray antennas are demonstrated at Ka-band with the capability of forming independent linearly polarized beams with a given polarization in each frequency band, while sharing the same radiating aperture. The proposed three-layer unit-cell is based on identical narrow microstrip patches printed on both receiving and transmitting layers and connected by a metallized via hole. The metal layers are printed on two identical substrates bonded with a thin film, and the designed unit-cell exhibits a 180° phase resolution (i.e., 1-b phase quantization). The dual-band dual-polarized property of the transmitarray is achieved by interleaving unit-cells operating in the down-link and up-link frequency bands. Four different prototypes are characterized to demonstrate the relevance of the proposed concepts. A good agreement is obtained between the radiation patterns, gain curves, and cross-polarization levels measured and computed in both frequency bands and polarizations.

We present novel three-layer D-band linearly-polarized transmitarrays entirely fabricated using standard printed circuit board (PCB) processes. Three flat lenses comprising 1600 elements are designed to generate broadside and scanned beams. All lenses are synthesized using 8 unit cells (3-bit phase quantization). The combination of cells comprising probe-fed and aperture-coupled patches is proposed to overcome the design challenges due to technological constraints and achieve a wideband operation. The minimum design feature is 80 μm. The trade-offs in the design of the feed illumination are analyzed using adhoc numerical tools. A 10-dBi horn is eventually selected as source. The focal-to-diameter (F=D) ratio is 0.75 for all lenses. The broadside array attains a peak gain of 33.0 dBi and a -1-dB relative gain bandwidth of 11.7%, i.e. wider than that of state-of-the-art designs, in the 100-300-GHz band, which use more complex technologies and larger focal distances. The performance of the proposed antenna technology demonstrates its potential for low-cost high-capacity wireless backhauls beyond 100 GHz.

This communication presents the design of a linearly polarized transmitarray antenna for backhauling applications at V-band (57-66 GHz). The antenna is composed of a planar circular-shape array with 1264 unit-cells (UCs) printed on a three-metal layer standard printed circuit board, an ad hoc focal source, and a radome layer. A 3-b phase resolution has been selected to achieve a gain higher than 31 dBi over the whole unlicensed 60 GHz band and low sidelobe levels. The presence of the radome near the array is taken into account in the UC design. Experimental results are in line with the theoretical ones provided by an in-house CAD tool based on analytical model and electromagnetic simulations. The proposed design presents a measured broadside gain of 32.5 dBi at 61.5 GHz with an aperture efficiency of 42.7% and a wide 1-dB gain bandwidth of 15.4% (57-66.5 GHz).