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This paper presents a spatially distributed multi-input direct conversion receiver architecture based on interferometric correlations of wave signals for fifth generation systems and beyond. The proposed receiver scheme inherits the advantages of conventional six-port receivers. The spatially distributed multi-input architecture is based on the use of a set of equally spaced four antenna elements instead of using a six-port junction composed of four hybrid couplers or other alternative circuit-based topologies. In this paper, the mathematical modeling of the proposed receiver is derived and presented. Then, an experimental test bench that is fabricated to operate around 5 GHz is introduced in order to validate the proposed scheme and its theoretical results. Various modulations including BPSK, QPSK, QAM-16, and QAM-32 have been successfully studied and demonstrated by this receiver at a relatively low date rate of 1 mega symbol per second with a maximum error vector magnitude of 10.3%. The maximum bit rate is fundamentally limited by the speed of power detectors, which is linked to their high rise time in our experiments. It is anticipated that multiple hundred megabits and gigabits per second can be achieved with the proposed direct conversion receiver if higher speed power detectors are used. [ABSTRACT FROM AUTHOR]

In this paper, a 60-GHz broadband 8-by-1 gap-coupled microstrip antenna array is presented and experimentally investigated. The proposed antenna array has been implemented using a Miniature Hybrid Microwave Integrated Circuits (MHMIC) fabrication process on a thin ceramic substrate with εr = 9.9 and h = 127 μm. For a comprehensive characterization and to accurately evaluate losses, as well as manufacturing tolerances, the proposed antenna array structure has been implemented using two different feeding techniques. The first one adopts a grounded broadband via-hole less transition from coplanar to microstrip line (GCPW-to-MS), while the second one has involved a broadband waveguide (WR12) to microstrip transition, based on a ridged waveguide concept. The obtained results have demonstrated that the proposed gap-coupled array configuration provides an improved bandwidth (4.56%) and an enhanced gain (11.8 dBi), while maintaining a lower side-lobe level (13.4 dB). These outstanding performances make the proposed WR12 gap-coupled array structure a potential candidate for the future emerging 60-GHz short-range point-to-point wireless communication systems. [ABSTRACT FROM AUTHOR]

This study presents a compact circularly polarised array using tapered slot antenna fed by a substrate integrated waveguide (SIW) power divider. With the proposed topology, broadband circularly polarised property is achieved and total gain can be increased by controlling the element length, conserving the same footprint area. The different 2 × 2 cell configurations are investigated. Simple and integrated series-parallel SIW feed for the choose cell is presented. A 2 × 2 antenna array is designed and fabricated using SIW E-plane power divider. The measured 10 dB return loss and 3 dB axial ratio bandwidths are 35.65 and 32.3%, respectively. The measured antenna gain is 14.4 dBi at 35 GHz. [ABSTRACT FROM AUTHOR]

In this paper, a substrate integrated waveguide power divider is proposed on the basis of a recombinant topology that provides in-phase power division with an odd or even number of branches. The aim is to generate different types of power distribution to control sidelobe level in the antenna array. In this study, several power-divider designs were designed to demonstrate and validate the design approach. Each design consists of a cascade of steps and nfurcations, which were initially designed based on sinusoidal basis functions. These designs were simulated using the High Frequency Structure Simulator (HFSS) and shown to closely match the performance estimated using the basis functions. A substrate with thickness of 0.508 mm and dielectric constant of 2.94 is used. A three-way power divider with a binominal output taper is optimized and fabricated, showing good results in the bandwidth of interest from 72 to 81 GHz. Measurement results for a 3 \times 8 slot array antenna designed in conjunction with the proposed feeding network are presented and discussed. This design can be used to build up rectangular waveguide structures. The novel structure is expected to be useful in building sub-arrays of antenna in the development of millimeter-wave automotive radar systems. [ABSTRACT FROM PUBLISHER]

A class of three-dimensional planar arrays in substrate integrated waveguide (SIW) technology is proposed, designed and demonstrated with 8 \times 16 elements at 35 GHz for millimeter-wave imaging radar system applications. Endfire element is generally chosen to ensure initial high gain and broadband characteristics for the array. Fermi-TSA (tapered slot antenna) structure is used as element to reduce the beamwidth. Corrugation is introduced to reduce the resulting antenna physical width without degradation of performance. The achieved measured gain in our demonstration is about 18.4 dBi. A taper shaped air gap in the center is created to reduce the coupling between two adjacent elements. An SIW H-to-E-plane vertical interconnect is proposed in this three-dimensional architecture and optimized to connect eight 1 \times 16 planar array sheets to the 1 \times 8 final network. The overall architecture is exclusively fabricated by the conventional PCB process. Thus, the developed SIW feeder leads to a significant reduction in both weight and cost, compared to the metallic waveguide-based counterpart. A complete antenna structure is designed and fabricated. The planar array ensures a gain of 27 dBi with low SLL of 26 dB and beamwidth as narrow as 5.15 degrees in the E-plane and 6.20 degrees in the 45^\circ-plane. [ABSTRACT FROM PUBLISHER]

This communication presents a low-cost 77-GHz switched-beam slot antenna array driven by a Butler matrix. In the proposed configuration, four broadband couplers are combined and crossovers are effectively avoided. In this case, the overall circuit and beamforming network losses are considerably reduced. A 4\,\times\,4 planar SIW Butler matrix is designed and demonstrated for integrated beamforming network applications, which exhibits about 7 degrees phase error and \pm 0.75~dB coupling imbalance over 11% bandwidth. This experimentally prototyped matrix is integrated with a four-array slot antenna on the same substrate. An alternating displacement of the slots in subsequent radiating waveguides is proposed to save the arrangement of the input ports and to achieve broadband performances. Measured radiation patterns are in good agreement with simulated counterparts over the proposed 77-GHz frequency range. [ABSTRACT FROM PUBLISHER]

Significant advances in the development of millimeter-wave and terahertz (30–10 000 GHz) technologies have been made to cope with the increasing interest in this still not fully explored electromagnetic spectrum. The nature of electromagnetic waves over this frequency range is well suited for the development of high-resolution imaging applications, molecular-sensitive spectroscopic devices, and ultrabroadband wireless communications. In this paper, millimeter-wave and terahertz antenna technologies are overviewed including the conventional and nonconventional planar/nonplanar antenna structures based on different platforms. As a promising technological platform, substrate-integrated circuits (SICs) attract more and more attention. Various substrate-integrated waveguide (SIW) schemes and other synthesized guide techniques have been widely employed in the design of antennas and arrays. Different types of substrate-integrated antennas and beamforming networks are discussed with respect to theoretical and experimental results in connection with electrical and mechanical performances. [ABSTRACT FROM PUBLISHER]

Millimeter wave applications such as short-range high-speed wireless links require modular, compact-size and high-directivity antennas. In this paper, high-gain compact stacked multilayered Yagi designs are proposed and demonstrated in the V-band. This novel design shows for the first time an antenna array of Yagi elements in millimeter wave stacked structure. To demonstrate the proposed concepts and design features, a 4\,\times\,4 antenna array is created having excellent gain performance as well as very small footprint. A single element stacked Yagi antenna fed with microstrip is studied in order to obtain the desired performance. An analysis is performed to define the structure limitations. Measured results of the fabricated antenna prototypes are in good agreement with simulated results The measured Yagi antenna attains 11 dBi gain over 4.2% bandwidth with a size of 6.5\,\times\,6.5\,\times\,3.4 mm^3. A 4\,\times\,4 array of Yagi antenna using an SIW (Substrate Integrated Waveguide) feeding technique is conceived. Both simulated and measured results match with each other very well. The 4\,\times\,4 array has a size of 28\,\times\,24\,\times\,2.4 mm^3, and reaches a measured gain of 18 dBi over 7% bandwidth. An alternate configuration of the array using angled Yagi antenna elements allows a significant improvement of the side lobe level (SLL) with a low impact on the gain performances. The proposed antennas are excellent candidates for integrated low-cost millimeter-wave and even terahertz systems. The small foot print, the antenna design flexibility as well as its easy adaptation to automatic fabrication processes are good assets for making short range portable imaging systems. [ABSTRACT FROM AUTHOR]

The growing complexity of satellite and mobile communication systems means that there are increasing needs for antenna arrays with multiple-beam capability. Conventional beamforming-network (BFN) configurations can be realized by different types of transmission lines, such as a microstrip line or waveguide. However, each of these has its own obvious defects. As part of a new generation of high-frequency integrated circuits, called substrate integrated circuits (SICs), substrate-integrated-waveguide (SIW) technology combines the benefits of both planar transmission-line and non-planar-waveguide technologies. It presents an excellent solution for the design and implementation of high-frequency beamforming networks, including for use at millimeter wavelengths. This paper overviews the state-of-the-art of substrate-integrated-waveguide techniques in the design and realization of innovative beamforming networks, and multibeam antenna arrays for low-cost satellite and mobile systems. Different classes of substrate-integrated-waveguide-based structures are theoretically and experimentally studied and demonstrated, to offer unprecedented performance and opportunities for specific space-and ground-based applications. [ABSTRACT FROM PUBLISHER]

This article presents an efficient ultra-miniaturized metasurface-based antenna array with high gain and wider bandwidth for millimeter-wave applications. The presented 1 × 2 compact array incorporates two patches with rectangular slots for gain, impedance matching, and bandwidth enhancement. Further performance is improved by designing a single-layer compact reflecting metasurface with a 2 × 4 array of diamond-shaped split-ring unit cells, where each unit cell has a compact size of only 1.35 × 1.35 mm 2. A Fabry–Perot cavity is created by positioning this metasurface at approximately 0.5 λ 0 (where λ 0 is the wavelength in millimeters) above the antenna array. This integration allows for improved performance and reduced interference between the metasurface and the antenna array. Moreover, the proposed configuration has achieved a wider bandwidth of 5.96 GHz (27.38–33.34 GHz), a maximum gain of around 12.7 dBi, and a radiation efficiency of 94% despite its 20. 5 × 20. 6 × 0. 508 mm 3 miniaturized size. The design is validated by testing the fabricated prototypes. Compared to state-of-the-art literature, the proposed design renders itself a feasible solution for millimeter wave communication devices and systems owing to its smaller physical footprint, broader bandwidth, higher gain, and improved radiation efficiency. [ABSTRACT FROM AUTHOR]