Coupling Slot Research Articles

Wideband circularly polarized dielectric resonator antenna with multi-functional metasurface assistance for low profile

ABSTRACT A low-profile broadband circularly polarized (CP) dielectric resonator antenna (DRA) is proposed, utilizing DR reutilization and metasurface (MS) techniques. Two resonant frequencies and an AR minimum are achieved simultaneously, by exciting a rectangular DR with an inclined corner-truncated coupling slot, for it generates nearly degenerated TE111 modes. For significant bandwidth enhancement and low profile, a new resonator is formed by reusing the DR and loading an MS above, which works in orthogonal TM modes. To increase the axial ratio bandwidth (ARBW) further without enlarging the antenna size， two parasitic patches are printed on two adjacent side walls of the DR. To verify the rationality and feasibility, the antenna is fabricated and measured. The fabricated prototype possesses the profile of 0.06λ 0 (λ 0 is the free-space wavelength at the center frequency). The measured impedance bandwidth (IBW) and ARBW are 36.05% (4.23 ~ 6.09 GHz) and 22.46% (4.9 ~ 6.14 GHz), respectively. The proposed antenna has both broadband characteristics and a low profile, making it easy to integrate into space-limited wireless communication systems with high data rates.

A high‐power, high‐isolation, dual‐polarised planar phased array antenna

AbstractA high‐power, high‐isolation, dual‐polarised planar phased array antenna is presented. Based on a multi‐layer microstrip structure, two sets of polarisation ports are fed through orthogonal slot coupling, achieving high isolation and low cross‐polarisation. Double‐layer radiation patches and cavity interlayers are used to expand the bandwidth and increase the gain. Metal vias are added around microstrip feeders and between array units to suppress surface waves, thereby improving the scanning performance of the phased array. A smooth gradient microstrip structure is designed to improve the power capacity while realising broadband impedance matching. The measured results show that in the 8–10 GHz frequency band, the isolation of the dual polarisation ports is greater than 50 dB, and the impedance bandwidth reaches 22.2%, with active VSWR <1.5 when not scanning. Both sets of polarisation can achieve 2‐D beam scanning in the range of E‐plane ±20° and H‐plane ±40° without grating lobes, maintaining the scan loss below 2.4 dB, cross‐polarisation below −20 dB and active VSWR <2. Each unit achieves a high gain of 7.4 dB and large power capacity of 5 kW; so the entire 8 × 8 phased array can achieve a main lobe gain of 25.5 dB and realise high‐power directional radiation with the effective isotropic radiated power of 92.5 dBm. The proposed planar antenna has a low profile of 5.5 mm (0.17λ0).

Exploring torque characteristics of an integrated ultra conducting magnetic coupling incorporating axial magnetic field through magnetic equivalent circuit modelling

Ultra-conductors are a recent class of materials that display superconducting attributes at room temperature and even at higher temperatures. In this paper, we introduce a novel hybrid ultra-conducting coupling (NHUC) where the secondary component includes copper and an ultra-conductor (considered as a room temperature superconductor in much research). We suggest a model based on magnetic equivalent circuit (MEC) to evaluate the distribution of magnetic fields and characteristics related to torque. The 3D model accounts for boundary impacts during mating, and formulation for magnetic flux and torque are derived using Kirchhoff’s and Ampere’s loop laws, respectively. A 3D finite element (FEM) model is constructed, and simulations are performed using iodine-doped double-walled carbon nanotube (IDWCT) as the ultra-conductor for a wider operating range. At a high slip speed of 1200 rpm, a maximum torque of 309 Nm and stable torque of 113 Nm are observed. Adjusting air gap thickness or permanent magnet dimensions results in torque variations. Additionally, due to carbon nanotube (CNT) characteristics, a reduction in losses from the Joule effect is noted. The maximum error between torque results from simulation and the suggested model is 7.68%, confirming accordance. Comparison alongside the slotted eddy current coupling (SEC) reveals that the torque of the NHUC exceeds that of the SEC, diminishing as the air gap widens.

A Fifth-Order X-Band Frequency-Selective Surface With High Selectivity and Angular Stability Based on 3-D Coupling Slot

A Fifth-Order X-Band Frequency-Selective Surface With High Selectivity and Angular Stability Based on 3-D Coupling Slot

Active and Passive Lenses From Coupled Square Ring Slots

Active and Passive Lenses From Coupled Square Ring Slots

High-efficiency single-layer corporate-feed gap waveguide based circularly polarized antenna array with compact size

A high-efficiency, single-layer gap waveguide based circularly polarized (CP) metasurface (MTS) antenna array has been proposed at Ka-band, employing a combination of printed circuit board (PCB) and machining techniques. The coupling slot parallel to the feeding ridge is proposed, which can be beneficial for designing single-layer ridge gap waveguide (RGW) networks, avoiding the traditional cavity layer and reducing the transmission loss. The MTS elements in a 4 × 4 lattice of truncated-corner patches are etched on a single substrate layer for lightweight and low-cost, validating the concept of a compact mixed design that can be easily adapted to other printed CP antennas. A 4 × 4 MTS array prototype was fabricated and tested. The impedance bandwidth and axial ratio bandwidth are 26–31.3 GHz (18.5%) and 28.2–33 GHz (15.7%), respectively. Over the entire operating bandwidth of 28.2–31.3 GHz (10.4%), antenna radiation efficiency exceeds 82%, and the maximum realized gain at 29.2 GHz is 21.2 dBi. The designed broadband MTS antenna array is efficient, compact, and suitable for certain millimeter-wave communication applications.

A high-gain circularly polarized magnetoelectric dipole antenna array with metallic radiating structure for millimeter-wave applications

A high-gain circularly polarized (CP) magnetoelectric (ME) dipole antenna with metallic radiating structure is presented. The proposed CP antenna element consists of two pairs of metallic posts with a supporting metallic plate, a metallic air-filled elliptical cavity, and a feeding slot on the bottom substrate integrated waveguide (SIW). The two pairs of modified rectangular metallic posts combined with the gaps between them act as radiating ME-dipoles which are surrounded by a metallic air-filled elliptical cavity. The above-mentioned radiating structures are fed by a modified cross-shaped coupling slot etched on the bottom feeding SIW to generate CP radiation, where loading the elliptical metallic cavity significantly improve the CP performance of the antenna element. Then, a 4 × 4 antenna array with full-corporate feeding network is designed, fabricated, and measured, which has an impedance bandwidth of 18.9 % from 37.4 to 45.2 GHz and a 3-dB axial ratio (AR) bandwidth of 14.2 % from 36 to 41.5 GHz. Thanks to the all-metal radiating structures, a maximum measured gain of 20.4 dBic has been achieved. The measured and simulated results are in good agreement.

Multilayer circular SIW cavity differential bandpass filter with wide‐stopband characteristics

AbstractIn this paper, a compact differential bandpass filter with wide‐stopband is presented. The proposed differential filter is designed using two circular substrate‐integrated waveguide (SIW) cavities coupled through a pair of symmetric coupling slots. The filter operates in TM110 mode of the circular SIW cavity. The degenerate TM110 mode is shifted to higher frequency by the introduction of two pairs of perturbation vias. The center frequency of the differential passband can be tuned by changing different design parameters such as location of perturbation vias and length of the slotlines. As a proof of the proposed concept, a second‐order differential bandpass filter is designed, fabricated, and measured. The measured results are in good agreement with the electromagnetic‐simulated ones.

A Compact Millimeter-Wave Multilayer Patch Antenna Array Based on a Mixed CPW-Slot-Couple Feeding Network.

A compact Ka-band antenna array has been proposed to realize broadband and high gain for millimeter-wave applications. The antenna array is divided into a multilayer composed of a driven slot patch layer and a parasitic patch array layer, which is excited by a mixed CPW-Slot-Couple feeding network layer. According to characteristic mode analysis, a pair of narrow coupling slots are introduced in the driven patch to move the resonant frequency of characteristic mode 3 to the resonant frequency of characteristic mode 2 for enhanced bandwidth. In this article, a 1to4 CPW-Slot-Couple feeding network for a 2 × 2 driven slot patch array is implemented, and then each driven slot patch excites a 2 × 2 parasitic patch array. Finally, a proposed 4 × 4 × 3 (row × column × layer) Ka-band antenna array is fabricated to verify the design concepts. The measured results show that the frequency bandwidth of the antenna array is 25 GHz to 32 GHz, and the relative bandwidth is 24.5%. The peak gain is 20.1 dBi. Due to its attractive properties of miniaturization, broadband, and high gain, the proposed antenna array could be applied to millimeter-wave wireless communication systems.

Design of Cross-Coupled Bandpass Filters with Flexible Coupling via Half-Mode Substrate-Integrated Waveguide

In this article, a simple approach for achievement of flexible coupling is presented based on the half-mode substrate-integrated waveguide (HMSIW). Since both electric and magnetic fields vary along the magnetic wall of the HMSIW, there exists mixed coupling between two adjacent HMSIWs. In this context, only by adjusting the width of the coupling slot at specific regions, both coupling property and strength can be conveniently controlled. Besides, as the coupling slot possesses the merits of simple structure and high flexibility, it is also expected to achieve desired couplings between multimode resonators. For demonstration, three cross-coupled bandpass filters (BPFs) with different kinds of frequency responses are constructed based on the typical cascaded trisection coupling topology by mixing one SIW and two HMSIWs, including two single-band and one dual-band designs. All measured results are highly consistent with the simulated ones, validating that the HMSIW not only has the inherent advantage of smaller size than the conventional SIW counterparts but also possesses unique feature in providing flexible coupling without extra circuit.

Development of a metasurface-based slot antenna for 5G MIMO applications with minimized cross-polarization and stable radiation patterns through mode manipulation

This paper presents an approach for designing metasurface antennas using the characteristic mode analysis method for 5G mm-wave multiple input–multiple output (MIMO) systems. The proposed metasurface antenna consists of a 3 × 3 array of modified patches with additional slits and stubs, which are fed by a coupling slot. This configuration reshapes surface currents and improves the radiation performance across a broad frequency range. The design offers significant advantages such as reduced antenna size, minimized influence of higher-order modes, and maintained low cross-polarization (XP) level. Experimental results demonstrate that the proposed metasurface-based slot antenna provides a bandwidth of 29.6% (23–31 GHz) with a return loss better than 10 dB. It achieves a peak gain of 9.43 dB and exhibits an XP level below − 26 dB and − 48 dB at φ=0∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varphi = 0^{ \\circ }$$\\end{document} and φ=90∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varphi = 90^{ \\circ }$$\\end{document} planes, respectively. The physical dimensions of the antenna are 0.9λ0 × 0.9λ0 × 0.08λ0, where λ0 is the free space wavelength at 27 GHz, resulting in an approximately 41% reduction compared to the conventional metasurface patch antenna. Moreover, the design proves to be well-suited for MIMO systems, enabling close placement of antenna elements without degrading their radiation patterns. The experimental results in 1 × 2 and 2 × 2 MIMO configurations represent that the isolation between antenna elements are better than 18 dB and 21 dB, respectively. The performance of the antennas remains stable in both configurations, effectively addressing concerns such as beam squint and eliminating the common issue of beam splitting observed in conventional metasurface MIMO antennas. Moreover, the envelope correlation coefficient value in both MIMO configurations is lower than 0.003. This significant advancement offers a promising solution for compact 5G mm-wave massive MIMO applications.

Dual‐mode dielectric resonator antenna design with stub‐loaded feeding slot

AbstractA dual‐mode dielectric resonator antenna based on a microstrip line‐slot coupling feed, operating in both the GMS‐900 and GMS‐1800 frequency bands, is presented. The antenna structure consists of a rectangular dielectric substrate and a cylindrical dielectric resonator, which is fed by a microstrip line‐slot coupling. The cylindrical resonant cavity and the dual‐stub coupling slot are designed so that the HEM111 and HEM311 modes are excited simultaneously, resulting in resonance at the two desired frequency points. The gain of the antenna is 3.74 and 7.63 dBi at 0.9 and 1.8 GHz respectively, and the efficiency of the antenna is greater than 70% in both operating bands.

A novel wideband compact circularly‐polarized metasurface antenna for modern vehicular communication systems

AbstractIn this work, a wideband compact circularly polarized (CP) antenna using a novel polarization‐rotated metasurface (MS) structure is presented. First, the polarization‐rotated MS structure is designed by using a complementary L‐shaped MS unit cell. By optimizing the width of diagonal gap and radius of corners, the amplitude and phase of its surface impedances along ±45° can be adjusted respectively, and then a large polarization‐rotated bandwidth of 44.4% can be obtained. Secondly, the modal behaviors of the proposed MS are also investigated by adopting characteristic mode analysis (CMA) to explore feasible CP radiation. Furtherly, the proposed MS is applied to construct a wideband CP MS‐based antenna by combining with a coupling slot. The experimental results show a large 3‐dB axial ratio (AR) bandwidth (~31.1%), a large 10‐dB impedance bandwidth (~41.8%) and a compact size of 0.63λ0 × 0.63λ0 × 0.08λ0, verifying that the proposed antenna can be applied to realize a high‐quality vehicular communication.

Wide-Angle Beam Steering Closed-Form Pillbox Antenna Fed by Substrate-Integrated Waveguide Horn for On-the-Move Satellite Communications

Wide-angle mechanical beam steering for on-the-move satellite communications is presented in this paper based on a closed-form pillbox antenna system. It includes three main parts: a fixed-feed part, which is a substrate-integrated waveguide (SIW) horn with an extended aperture attached to a parabolic reflector; a novel quasi-optical system, which is a single coupling slot alongside and without spacing from the parabolic reflector; and a radiating disc, which is a leaky-wave metallic pattern. To make the antenna compact, pillbox-based feeding is implemented underneath the metallic patterns. The antenna is designed based on a substrate-guided grounded concept using leaky-wave metallic patterns operating at 20 GHz. Beam scanning is achieved using mechanical rotation of the leaky-wave metallic patterns. The proposed antenna has an overall size of 340 × 335 × 2 mm3, a gain of 23.2 dBi, wide beam scanning range of 120°, from −60° to +60° in the azimuthal plane, and a low side lobe level of −17.8 dB at a maximum scan angle of 60°. The proposed antenna terminal is suitable for next-generation ubiquitous connectivity for households and small businesses in remote areas, ships, unmanned aerial vehicles, and disaster management.

Multiobjective Optimization Design of Microstrip Directional Coupler With Generalized Coupling Slots

Multiobjective Optimization Design of Microstrip Directional Coupler With Generalized Coupling Slots

Effective Design of an Array of Coupling Slots with a Reflection-canceling Wall for a Parallel-plate Slot Array Antenna

Effective Design of an Array of Coupling Slots with a Reflection-canceling Wall for a Parallel-plate Slot Array Antenna

A high gain circularly polarised magnetoelectric dipole antenna array with metallic radiating structures for millimetre‐wave applications

AbstractAn antenna array design method of trade‐off between high gain and low profile is proposed. A high‐gain circularly polarised (CP) substrate integrated waveguide (SIW)‐fed magnetoelectric dipole (ME‐dipole) antenna array with metallic radiating structures is presented for millimetre‐wave (MMW) applications. The CP antenna element comprises a set of horizontally and vertically metal plates and a metallic cavity that is excited by an X‐shaped coupling slot etched on the broader side of SIW. The metallic cavity is designed to improve the gain and axial ratio (AR) performances. Utilising this antenna element, a proof‐of‐concept is established through the design of a 2 × 2 subarray and a 4 × 4 array. The fabricated 4 × 4 CP antenna array has a measured impedance bandwidth of 6.1% (36.4–38.7 GHz), with |S11| ≤ −10dB. The measured 3dB AR bandwidth is 5.4% (36.0–38.0 GHz). The measured maximum gain achieved is 19.1 dBic. The height of the proposed array is 0.74λ0 which is larger than the heights of typical SIW‐based microstrip arrays (0.1–0.4λ0) and lower than the heights of metallic arrays (larger than 2λ0).

Analysis of Wide‐Angle Scanning of High‐Power Microwave Waveguide Slot Array Antenna

In the design of high‐power microwave (HPM) waveguide array of longitudinal shunt slots, the mutual coupling of slots in different waveguide can badly decrease the capability of wide‐angle scanning of array. An L‐band HPM waveguide array of longitudinal shunt slots is designed. The choke groove was designed to restrain the mutual coupling of slots of the HPM array antenna. The result of simulation verified that the scanning angle with the gain of antenna decreased of 3 dB of array without choke groove structure is only 25°, and that is 35.0° with choke groove structure. The wideband of active reflection of array can be improved by the choke groove structure. The result of experiment also verified that the slot array antenna provided 30° beam steering with a gain reduction of 1.8 dBi and the power‐handling capacity of the array with the choke groove is greater than 1.5 GW with width of pulse of 42 ns. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Broadband Miniaturized C-Band Stacked Antenna Design and Analysis Using TLM

This paper presents the design of broadband miniaturized C-band stacked antenna and its analysis using TLM . The proposed antenna operates at C-band and acquires 45% bandwidth with a peak gain of 8 dBi. The generalized transmission-line model, developed earlier for the analysis of multilayered stacked antennas (without slots), has been implemented and modified for the analysis of the proposed antenna (having a slot in the driven patch). The slot coupling effect is incorporated in the modified TLM model for the circuit-level simulation and analysis of the designed antenna. Circuit simulation results agree with EM simulation and measured results. The proposed antenna occupies an overall volume of 52 × 50 × 4.5 mm3, while volume of the radiating elements is 13 × 19.89 × 4.5 mm3, which makes the design quite compact. The proposed stable antenna has unidirectional radiation patterns throughout the band of operation and is thus suitable for applications such as remote sensing, target detection, and imaging.

Millimeter-Wave and Short-Range Wireless Communication Antenna Based on High-Conductivity Graphene-Assembled Film.

Millimeter-wave and short-range wireless communication is an important part of the Internet of Things due to its advantages of high transmission speed and large data capacity. In this paper, two antenna arrays operating at typical millimeter-wave bands (45 and 60 GHz) based on graphene-assembled films (GAF) are proposed for short-range wireless communication application. The 45 GHz graphene-assembled film antenna array is in the form of a magnetoelectric dipole antenna with a strip slot coupling to achieve bidirectional radiation, which offers an operating bandwidth of 40-49.5 GHz with a realized gain of 11.8 dBi. The 60 GHz graphene-assembled film antenna utilizes a microstrip discontinuous radiation array to achieve radiation with an operating bandwidth of 59-64 GHz, reaching the peak realized gain of 14.92 dBi over the working frequency. Finally, we proposed an experimental validation to verify the transmission performance of both antenna arrays in an actual conference room. The results show that the signal drops slowly in the room with drop rates of 0.064 dB/cm (at 45 GHz) and 0.071 dB/cm (at 60 GHz), while it steeply dropped through the wall with the drop rates of 2.3 and 3.13 dB/cm, more than 35-fold difference in signal drop rates in the room and through the wall. It has been confirmed that the proposed antenna arrays can successfully realize fast indoor short-range wireless communication while also preventing signal leakage through walls, thereby enhancing the security of information. In summary, this is the first time that we have applied graphene-based materials to millimeter-wave and short-range wireless communications, revealing the significant potential of carbon-based materials in high-frequency communication systems.