This paper presents a flat, high gain, wide scanning, broadband continuous transverse stub (CTS) array. The design procedure, the fabrication, and an exhaustive antenna characterization are described in details. The array comprises 16 radiating slots and is fed by a corporate-feed network in hollow parallel plate waveguide (PPW) technology. A pillbox-based linear source illuminates the corporate network and allows for beam steering. The antenna is designed by using an ad hoc mode matching code recently developed for CTS arrays, providing design guidelines. The assembly technique ensures the electrical contact among the various stages of the network without using any electromagnetic choke and any bonding process. The main beam of the antenna is mechanically steered over ±40° in elevation, by moving a compact horn within the focal plane of the pillbox feeding system. Excellent performances are achieved. The features of the beam are stable within the design 27.5-31 GHz band and beyond, in the entire Ka-band (26.5-40 GHz). An antenna gain of about 29 dBi is measured at broadside at 29.25 GHz and scan losses lower than 2 dB are reported at ±40°. The antenna efficiency exceeds 80% in the whole scan range. The very good agreement between measurements and simulations validates the design procedure. The proposed design is suitable for Satcom Ka-band terminals in moving platforms, e.g., trains and planes, and also for mobile ground stations, as a multibeam sectorial antenna.

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.

An integrated solution for the development of multilayer antenna modules for fifth-generation (5G) communications, based on low temperature cofired ceramic (LTCC), is presented. The design exploits the 3-D integration capabilities of the LTCC process, enabling the realization of a full-corporate feed network (CFN) in vertical configuration. A novel implementation of the CFN employing dielectric-embedded parallel plate waveguides (PPWs) is proposed. The PPW lines are delimited by via-rows. As opposed to standard substrate-integrated waveguide feed networks, guided fields are orthogonal to the via-rows and propagate along the vertical axis of the structure. The CFN feeds four long slots, without any coupling structure, and provides broadband operation. The final prototype comprises 18 LTCC tapes, with a total thickness of 3.4 mm. The measured -10-dB impedance bandwidth spans from 51.2 to 66 GHz (>25.2%). The module generates a fixed broadside beam, but multibeam operation in H-plane can be easily achieved. In the 50-66-GHz band, the peak gain is 14.25 dBi and the average first side-lobe level in H-plane is -20.6 dB. The proposed technology and the design concept are suited for highly integrated millimeterwave systems, such as access points in the future V-band high data-rate wireless networks.

Wide-angle coverage, fine angular resolution and low-power consumption are key characteristics of millimeterwave (mm-wave) short-range wireless systems, such as access points in fifth-generation (5G) cellular networks and automotive radars. In this paper, we present a 60-GHz switched-beam antenna system addressing all these requirements. It consists of two identical parallel-fed arrays of 8 slots, each fed by a passive pillbox beamformer. A switch network comprising four singlepole- multiple-throw (SPnT) switches excites one of the two arrays at a time and selects the radiated beam. The whole system is fully-integrated in a multilayer low temperature co-fired ceramic (LTCC) module. The antenna covers a scan range of about ±39° in one plane using eleven beams, between 57 GHz and 66 GHz. The proposed architecture enables the simultaneous achievement of continuous coverage (beam crossover levels of about -3 dB) and of low sidelobe levels (SLLs). Dedicated numerical tools are used for a preliminary design of the antenna. The design procedure, the technological development and the experimental results are discussed in detail.

This paper introduces a rigorous and effective modeling framework for the continuous transverse stub (CTS) array, based on a spectral Green's function approach. A multimodal expansion of the equivalent currents over the slots is used to derive an accurate expression for the active impedance of an infinite array. This formula is validated through comparisons with full-wave simulations when the array scans are in principal planes. The mathematical formulation highlights the broadband properties of CTS arrays and accurately predicts the impact of the geometrical parameters on the active impedance, as a function of frequency and scan angle. The discussion of the results provides physical insights to outline effective design strategies.

A novel approach for studying and designing low-cost anisotropic transmitarrays (TAs) at sub-THz frequencies is presented here. The array comprises three metal layers and two interleaved dielectric spacers. A four-port equivalent circuit model is derived to accurately model the anisotropic behavior of the unit cell (UC). The analysis proves theoretically that nearly perfect transmission and complete phase control can be achieved at the same time. A systematic procedure optimizing the admittance tensor of the inner layer is described for the UC design. A 3 bit TA antenna at 300 GHz is fabricated using a standard printed circuit board (PCB) process. The measured results demonstrate that the design methodology is effective even under strict technological constraints. The antenna achieves a peak gain of 32.2 dBi with 36.5% aperture efficiency and 70.4 GHz of 3 dB bandwidth.