A high equivalent isotropic radiated power (EIRP) active phased array antenna is proposed for fifth-generation (5G) communication systems at 28 GHz. The numerical design, measurements of a fabricated prototype, and performance analysis are presented. The antenna design is based on the gapwaveguide technology and consists of 16×16 single 45° slant-polarized elements. The proposed design uses a low complexity printed circuit board (PCB) structure with only six layers, i.e., a half of the existing wideband solutions. The array antenna incorporates up/downconverter integrated circuits (UDCs) and 1×4 transceiver beamformer integrated circuits (BFICs). Moreover, a compact and highly efficient transition at the end of each channel of the BFICs has been designed to interconnect the antenna elements with the PCB. The antenna’s front-end loss, which includes the feed line, mismatch, and ohmic losses, is only 1.3 dB. The array covers the scanning range of ±60° in the azimuth plane and ±10° in the elevation plane. The S11<−10 dB frequency bandwidth is from 26.5 to 29.5 GHz. The maximum EIRP of the antenna is 65.5 dBm at saturation point. The presented design offers a compact, robust, and low-loss performance solution meeting the high transmission power requirements of 5G applications.

A cost-efficient, high equivalent isotropic radiated power (60 dBm), large-bandwidth (26.5–29.5 GHz) active phased array antenna system has been designed and experimentally verified. The proposed design methodology results in a reduction of production costs by employing gallium nitride (GaN)-based radio frequency front-ends (RFFEs) with 31 dBm output power allowing a reduced number of antenna elements. A fully metallic gapwaveguide (GW) technology has been employed achieving efficient heat dissipation per aperture area of the array as well as low-loss easy-to-manufacture antenna elements. The phased array is realized by sub-arraying an 8×8 slot array antenna with horizontal polarization. A ±60° analog beamforming in the E-plane is demonstrated. The presented antenna is a potential candidate for compact-size high-performance fifth-generation (5G) base station antennas with excellent temperature stability.

A vertically polarized subarray antenna based on Gap Waveguide technology has been designed for Joint Communication and Sensing (JCAS) systems operating at the center frequency of 77 GHz. The proposed subarray consists of two radiating layers with an in-between cavity layer. The first layer is comprised of 3 up-pointing V-shaped slots with the inter-element spacing of λ and the second layer has 6 transverse-arranged slots that are employed to obtain vertical polarization. The S11 < –10 dB frequency bandwidth is from 75.7–78.3 GHz. The achieved peak Gain is 13.8 dBi at 77 GHz.

The millimeter-wave (mmWave) and sub-terahertz (sub-THz) bands have received much attention in recent years for wireless communication and high-resolution imaging radar applications. The objective of this paper is to provide an overview of recent developments in the design and technical implementation of GW-based antenna systems and components. This paper begins by comparing the GW-transmission line to other widely used transmission lines for the mmWave and sub-THz bands. Furthermore, the basic operating principle and possible implementation technique of the GW-technology are briefly discussed. In addition, various antennas and passive components have been developed based on the GW-technology. Despite its advantages in controlling electromagnetic wave propagation, it is also widely used for the packaging of electronic components such as transceivers and power amplifiers. This article also provided an overview of the current manufacturing technologies that are commonly used for the fabrication of GW-components. Finally, the practical applications and industry interest in GW technology developments for mmWave and sub-THz applications have been scrutinized.

First, we show that an array antenna thinned for maximum ergodic sum rate in regularized zero forcing massive MIMO single-cell systems comes with an increased average peak sidelobe level (PSLL). Then, we propose a new hybrid-beamforming-based array layout that achieves PSLLs comparable with a conventional half-wavelength-spaced full-digital-array, while using as few RF chains as the thinned array.

A novel approach to mitigate diffraction effects from finite ground planes in antenna design is presented. The method is based on the conformal transformation optics. A computational framework has been developed to optimize the shape of the ground plane since it has a great impact on the beam ripple and width of the radiation pattern of an antenna. Due to the limited thickness of the outer wall of slotted waveguide antennas, it is not possible to shape this outer wall, which acts as the ground plane of the antenna. Conformal transformation optics presents a solution to virtually add a deformation without needing to change the physical shape of the ground plane. Although conformal transformation optics can also be applied to transverse-magnetic waves, large fluctuations in the dielectric constant with respect to the wavelength cannot be supported in practice. In order to mitigate this problem, we have proposed a rescaling of the dielectric constant. Furthermore, we derive the connection between conformal transformation optics and transverse electromagnetic modes, which serve as a tool for joint optimization of the radiation pattern together with the conformal transformation. This method is then used to optimize the radiation pattern of a slot antenna and evaluated for increasing curvature within the conformal transformation.Numerical computations have shown promising results, i.e. a reduction of the farfield ripple from 1.92 dB to 0.64 dB at a half-power beam-width of 112° at 77 GHz. This is a promising result for designing automotive radars with a wide field of view, especially, for advanced driver-assistance systems used in the corner radars. This will contribute to further improving safety on the roads.

In this paper, we propose quantifying the radiated power of phased arrays or, in general, directive antennas, by the Constrained-View Radiated Power (CVRP). The constrained view shall be interpreted here as the Field-of-View (FoV) of an antenna that defines a region in space where focusing the radiated power is highly desired. In the limiting cases, we have that CVRP equals the Total Radiated Power (TRP) when the FoV covers the whole sphere, while, if the FoV reduces to a single point in space, the CVRP equals the Equivalent Isotropic Radiated Power (EIRP). We further present an analysis based on measured radiation patterns of a 16-element, linearly polarized, millimeter-Wave (mmWave), planar phased array antenna operating at 28 GHz. We compare the results to two ideal planar array antennas with the same number of Huygens and cosine elements. The evaluated figure of merit is computed for different scanning angles, as well as for different malfunctions of antenna elements, both for the real and simulated arrays. The results show that the introduced figure of merit could be potentially used for the detection of malfunctioning elements in antenna arrays as well as to characterize the impact of scan loss. Furthermore, CVRP is useful to straightforwardly and significantly characterize the performance of a directive antenna in terms of the power radiated towards a specific region in space.

New figures of merit are introduced to characterize the correlation and the non-orthogonality of multiple beams produced by an array antenna or two different array antennas. The figures of merit take into account the correlation or non-orthogonality between beamforming fields of two separate arrays and the beams produced by each at once. As an example, two adjacent modified microstrip Franklin array antennas have been designed. The non-orthogonality and isolation between steered radiation patterns have been studied for arrays operating at the same center frequencies 77 GHz. Each array antenna consists of 5 linear sub-arrays with 10 rectangular microstrip patch elements. Chebyshev tapering and open circuit stubs have been applied to the microstrip patches to obtain a low side lobe level and better impedance matching between single elements, respectively. The achieved peak gain, minimum side lobe level (SLL) and impedance bandwidth are 14.1 dBi, −13.6 dB and 581 MHz for a single sub-array at 77 GHz, respectively. The evaluation has shown that the same pair of arrays have different non-orthogonality depending on the propagation channel. On the one hand, the evaluated array-pair shows highly uncorrelated performance in a rich isotropic multipath propagation environment. On the other hand, they show high non-orthogonality (or co-directionality ) in a pure line-of-sight channel as expected. Hence, depending on the propagation channel, the arrays can be used for different communication and sensing applications either jointly or independently.

In this paper, a low-profile tightly coupled dipole array (TCDA) with ultra-wideband (UWB) and wide scanning capability has been proposed for Ku-band communication. Several main new features of the designed antenna are presented. The proposed dipole is excited by a simplified Γ-shaped probe. A wide impedance bandwidth matching is achieved by three shorting posts connected to each dipole arm. The unwanted common mode is suppressed by means of an E-wall constructed from a pair of shorted strips beneath the dipole. Also, a metasurface (MS) is used as a wide angle impedance matching (WAIM) layer realized with H-shaped elements to increase the impedance matching performance of the proposed TCDA in both E- and H-planes. Numerical simulations show that the TCDA antenna has a relative bandwidth of 3.17 : 1 (10.3 − 32.7 GHz) at a VSWR ≤ 2.3 for broadside. The good performance is maintained for a 60° scanning angle from 10.5−22.5 GHz at a VSWR ≤ 2.6 in both the E- and H-planes. The proposed TCDA has a low profile and can be realized by a cost-effective multilayer substrate manufacturing making it a potential candidate for commercial applications.

This paper presents some ideas and results related to designing and characterizing intelligent devices and environments for wireless communications.