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This paper presents a 3 dB compact Ultra-Wide-Band (UWB) Substrate Integrated Gap Waveguide (SIGW) based hybrid coupler suitable for 5G mm-wave applications. It is a key component in signal processing for wireless communication. It provides a way to control the power distribution of the signal along different ports. It could be used to achieve beamforming and adaptive antenna system. The design steps started with implementing a unit cell of the gap waveguide structure satisfying the required bandwidth of the coupler. A supercell is then implemented. A network of complete ridges is constructed. A further step is to design a coupling section which achieves the required power distribution along the coupling and isolated ports. This coupling section is implemented using a novel approach of inserting an elliptical slot with variable major and minor axes with a certain orientation that achieves the standard performance of a 3 dB directional coupler with 90◦±5% phase shift. For precise adjustment of this amplitude and phase, vias are further added perpendicular to the major axis of the slot. Its dimension and location have to be optimized. The Finite-Integral-Time-Domain (FDTD) analysis method is adopted (CST Microwave Studio). In addition, another novel approach is developed on this coupler such that the transition and gap layer is implemented on the same PCB layer, which saves the number of layers to only two layers compared to the usual three layers used in literature. Also, using SIGW technology saves the collapse of the top ground layer on the ridge structure, and only plastic pins are used to fix the two layers. The proposed coupler is fabricated and tested, and the results show that it serves the majority of frequency bands employed in 5G systems in the USA and Canada. [ABSTRACT FROM AUTHOR]

E-plane sectoral horn antenna based on printed ridge gap waveguide (PRGW) technology is designed for 5G applications. It is implemented on the top plate of the PRGW structure to avoid the losses and dispersion associated with conventional feeding mechanisms. The quasi-transverse electromagneticPRGW-based antenna is excited through a planar microstrip transition. First, the single horn antenna element is introduced with the microstrip feeding section. It shows an impedance bandwidth of fractional bandwidth 26% from 45.7 to 55.4 GHz with the realized gain of 12.7 dBi and radiation efficiency of 90%. In order to maximize the realized gain, a four-element linear horn array is introduced. The same impedance bandwidth is maintained with the array having a gain of 18.6 dBi from 45.7 to 55.4 GHz. The overall antenna array performance in the entire operating frequency range is stable with a radiation efficiency around 85%. Three matching sections are implemented to achieve better impedance matching. One is used to match the horn with the feeding aperture via the PRGW line. Another section is designed to match microstrip transition with PRGW ridge. Finally, two-stage quarter wavelength transformers are required to match the power divider with the array feeding network. A prototype of single-element horn antenna was fabricated to verify the concept of the design. Simulated and measured results show that the proposed antenna can operate in the frequency band of 45–55 GHz with good agreement of radiation performance. Moreover, the proposed designs are implemented and simulated using two microwave simulation tools (CST and HFSS) to verify the radiation performance, which exhibits good agreement. The design of an E-sectoral horn antenna and its array with high gain based on PRGW is demonstrated for the first time which is considered a novel issue. It can be integrated with other passive and active elements in communication systems. Thus, it can be a valuable component in 5G communication due to its high gain, compact size and ultra-wide band. [ABSTRACT FROM AUTHOR]

In this paper, a submillimetric/THz metasurface polarization/oblique independent absorber is designed and characterized. The absorber is designed using a periodic arrangement of a modified split ring resonator unit cell. The symmetric absorber is insensitive to the variation of incident angles and polarization angles. The results confirm that perfect absorption is achieved (close to 100%) for either TM or TE polarization at 300 GHz. Moreover, the absorber is efficient for normal and oblique incident angle (above 90% for 45° angle of incidence). In all the presented cases, the full width half maximum bandwidth is 20 GHz. The absorber unit cell size is only 0.0052 λ0 × 0.0052 λ0 and it has a low-profile thickness = 0.0002 λ0, at the operating frequency. Also, an absorber-based biosensor is presented. The sensing has proved the coating analyte thickness can be detected by shifting the absorption frequency. The maximum sensitivity is 24.9% RIU−1 with a low-profile maximum of 50 µm thickness. Analytical formulas for the frequency shift have been extracted. The presented results are discussed based on 3D full-wave EM simulations. [ABSTRACT FROM AUTHOR]

This paper presents a printed multiple-input multiple-output (MIMO) antenna with the advantages of compact size, good MIMO diversity performance and simple geometry for fifth-generation (5G) millimeter-wave (mm-Wave) applications. The antenna offers a novel Ultra-Wide Band (UWB) operation from 25 to 50 GHz, using a Defective Ground Structure (DGS) technology. Firstly, its compact size makes it suitable for integrating different telecommunication devices for various applications, with a prototype fabricated having a total size of 33 mm × 33 mm × 0.233 mm. Second, the mutual coupling between the individual elements severely impacts the diversity properties of the MIMO antenna system. An effective technique of orthogonally positioning the antenna elements to each other increased their isolation; thus, the MIMO system provides the best diversity performance. The performance of the proposed MIMO antenna was investigated in terms of S-parameters and MIMO diversity parameters to ensure its suitability for future 5G mm-Wave applications. Finally, the proposed work was verified by measurements and exhibited a good match between simulated and measured results. It achieves UWB, high isolation, low mutual coupling, and good MIMO diversity performance, making it a good candidate and seamlessly housed in 5G mm-Wave applications. [ABSTRACT FROM AUTHOR]

This article presents a detailed analysis and design of an ultra-wideband (3.1 GHz-10.6 GHz) notch antennas in a two-element MIMO system with high isolation performance. The wideband spectrum is notched at the WiMAX band at 5.8 GHz center frequency using a highly selective electromagnetic bandgap structure coupled to the antenna feeding lines. An array of electromagnetic bandgap structure is used to achieve wideband isolation between the two elements. The two antenna elements achieve wideband reflection coefficient for good matching below -10 dB, except the notch where it becomes higher than -2 dB. On the other hand, the antenna elements have a minimum of 20 dB isolation. Thanks to the achieved results, the antenna MIMO elements have small envelope correlation (less than 0.05) and also small channel capacity loss (less than 0.2 bit/s/Hz). The obtained results are verified using experimental measurements and all circuit/EM needed simulations. [ABSTRACT FROM AUTHOR]

In this paper, a flexible single fed planar circular polarized slot antenna is proposed for Internet of Things wideband applications. The antenna flexibility is achieved by employing a mechanically bendable liquid crystalline polymer substrate. The overall antenna volume is 50 mm × 42 mm × 0.1 mm. The antenna design uses 45° rotated elliptical ground structure for generating circular polarized radiation over wideband spectrum. Two parametrical analyses targeting the slot ground are introduced in order to achieve the most efficient design. The final antenna design demonstrates a good matching in terms of reflection coefficient (<−10 dB), semi-omnidirectional radiation patterns, average gain of 4 dB, and <3 dB axial ratio over entire frequency band of operation. All antenna parameters are studied in both straight and bent antenna setup scenarios. Good agreement between simulation and measurement results of the antenna parameters are achieved. For both straight and bent antenna scenarios, the antenna receiving functionality in time domain is confirmed by retrieving highly correlated impulse responses. [ABSTRACT FROM AUTHOR]