Substrate Integrated Waveguide Slot Array Research Articles

Design of a Low-Cost, Low-Sidelobe-Level, Differential-Fed SIW Slot Array Antenna with Zero Beam Squint

This paper presents a low-cost, low-sidelobe-level, differential-fed, substrate-integrated waveguide (SIW)-based slot array antenna with zero beam squint. The antenna consists of two identical six-way unequal power dividers (PDs) and a 6 × 16 slot array and is realized on a single-layer substrate. The six-way unequal PD provides tapered amplitude and in-phase excitation for six SIWs, and each of them has 16 radiating slots. The 1 × 16 linear slot array on each SIW is excited using a differential feed to avoid undesired beam squinting across its operating band. A two-way hybrid waveguide (WG)-to-SIW E-plane PD is developed to provide equal amplitude and out-of-phase excitation for two six-way unequal power dividers. Moreover, metallic decoupling walls are implemented between two adjacent linear slot arrays to reduce E-plane external mutual coupling. An antenna prototype is fabricated and experimentally verified. The fabricated antenna shows that the measured −10 dB reflection bandwidth is 7.15% (9.57–10.28 GHz), with the achieved gain ranging from 20.30 to 21.92 dBi. A stable boresight beam is observed over the entire operating band. Furthermore, at the designed frequency of 10 GHz, peak SLLs of −29.1 dB and −29.4 dB are achieved in the E- and H-plane, respectively.

Wideband series feeding antenna array made of substrate integrated waveguide slot array and patch array

In this paper, a wideband two layer slot array antenna is proposed which operates in the frequency range of 12–14.4 GHz. The lower layer of the antenna array includes narrow rectangular slots and the upper layer consist of rectangular patches shorted on the sides of the patches with via holes. The wideband operation is obtained by making two resonances. One resonance is due to radiation of the single element and the other is the effect of mutual coupling between adjacent elements. An 8 element array is designed, simulated and fabricated with good agreement between simulated and measured results.

Substrate Integrated Waveguide Slot Array Antenna to Generate Bessel Beam With High Transverse Linear Polarization Purity

The transverse linearly polarized beam can maintain its polarization when reflected, which is important for a detection system. Most of the existing planar Bessel beam generators are implemented in a central feeding radial topology and hard to generate the Bessel beam with the transverse linear polarization. In this communication, a substrate integrated waveguide (SIW) slot array antenna is proposed to generate the transverse linearly polarized Bessel beam. The desired phase and amplitude distribution of the Bessel beam can be easily realized by such an array. With the inherent 0°/180° output phase of the comb-like divider considered, the desired 0°/180° phase distribution is implemented by placing adjacent slots on the opposite (0°) or the same side (180°) within a linear array and by employing adjacent linear arrays with the inverse (180°) or the same (0°) slot offset direction accordingly. The offset of the slot, as well as the tuning metalized vias within the comb-like divider, is modulated to generate the desired amplitude distribution. After reducing the influence of the rectangularly truncated aperture by adding a Gauss-tapered amplitude distribution, a transverse linearly polarized Bessel beam SIW slot array antenna is designed with more than 100 mm depth-of-field (DoF) and less than −25 dB cross polarization. To the best of our knowledge, it is the first design to generate the transverse linearly polarized Bessel beam by a planar array antenna.

Substrate-Integrated-Waveguide-Based Complementary Source Array With Enhanced Beamwidth

A complementary source array with enhanced beamwidth is presented based on the substrate-integrated waveguide (SIW) in this communication. The orthogonal complementary source consists of a SIW slot and a vertical monopole, of which the radiation pattern is heart-shaped, pointing to the direction perpendicular to both slot and monopole. To achieve an enhanced beamwidth from the heart-shaped pattern, the complementary sources are cascaded to form an array. In particular, the slots are etched alternately on both sides of the central axis to achieve an in-phase excitation, while the monopoles are uniformly loaded with an alternate antiphase excitation. This arrangement makes the heart-shaped pattern of each complementary source element alternately point to either side of the array axis, so that the synthesized radiation beamwidth is enhanced in the E-plane. Based on the proposed idea, a nine-element line array is designed, fabricated, and tested. Compared with the same-sized referenced SIW slot array with an E-plane half-power beamwidth (HPBW) of only 80°, the proposed complementary source array extends the HPBW to 180°.

A compact folded SIW multibeam antenna array for 5G millimeter wave applications

AbstractA novel compact multilayer multibeam antenna array based on substrate integrated waveguide (SIW) is proposed in this letter for 5G millimeter wave (mm‐wave) applications. A multimode beam forming network (BFN) cascaded by phase compensation and coupling structures is folded to make the antenna array more compact. The phase difference between the output ports of traditional multimode beamforming network is very unstable, which would seriously affect the multibeam performance of antenna array. Therefore, the compensating phase shifter adopts the SIW transmission line structure with unequal length and width, which enables the multimode BFN achieving better performance in the bandwidth of 27–29 GHz. Four slot arrays are employed as the radiation structure. The overall structure of the proposed antenna consists of three parts, including a multimode beamforming network, a compensated phase shifter, and an SIW slot array. If these components are cascaded directly, the size of the antenna would be very large and the aperture efficiency will be low. So the proposed antenna is folded into three layers, one part for each layer. The overall antenna size is 66.7 mm × 47.5 mm (6.23λ × 4.44λ at 28 GHz). The antenna array is designed, fabricated, and measured. The measured results show that four deflected beams are realized in the band of 27–29 GHz. The radiation beams demonstrate a wide azimuthal coverage of ±48 deg, and a peak gain of 16.8 dBi for Port 1 excitation and 17.3 dBi for Port 2 excitation. The simulated radiation efficiency is better than –2 dB from 27 to 29 GHz. The proposed antenna features a compact size, low profile, good radiation performance, which is well suited for applications in the 5G mm‐wave communication systems.

Compact three-beam antenna based on SIW multi-aperture coupler for 5G applications

In this paper, a new three-beam antenna is proposed based on substrate integrated waveguide (SIW) for 5G applications in the frequency range of 28–32 GHz. The radiating element is an SIW slot array antenna, which is fed by a new beamforming network (BFN). The proposed BFN consists of only one 3 × 3 multi-aperture coupler (MAC) and a 3 × 3 phase shifter. Due to the use of fewer components, the proposed BFN has a simple and compact structure compared to the conventional Butler matrix BFN. First, a MAC feeding network is designed, and then a multi-beam slot array antenna is designed and optimized by HFSS software to realize three beams in the directions of 40°, 0°, and −40°. The return loss and isolation of all three ports of the antenna are better than 10 dB from 28 to 32 GHz. The measured gains of the antenna are from 8 to 10.2 dBi for different beams in the operating frequency band. The area of the proposed antenna is 53.6 × 15.8 mm2, which shows about 42% reduction in comparison to the similar reported three-beam antenna. The fabricated antenna has been tested, and there is good agreement between the measured and simulated results.

Substrate Integrated Waveguide Slot Array antenna for Broadband Applications

This paper presents a design of substrate integrated waveguide slot array antenna for X and Ku band applications. This is a low weight and simple profile antenna covering a vast range of frequencies. A substrate integrated waveguide is formed by two rows of metallized cylinders connecting upper and bottom layer of substrate. On the metallic plate, slot arrays are etched in a periodic fashion to achieve broad bandwidth. The SIW is excited by the microstrip feeding through a tapered transition to achieve smooth flow of current. The simulated result shows that -10 dB return loss of the proposed antenna is -35 dB, -29 dB and -22 dB at 11.1 GHz, 12.7GHz and 17.6 GHz respectively. The simulated bandwidth of the design is 7.6 GHz from 10.4-18 GHz which covers X band partially and Ku band. The gain of the antenna is about 6 dB. The proposed design is simulated using 3D full wave simulator named Ansys HFSS.

Generating and 2-D Steering Large Depth-of-Field Beam by Leaky-Wave Antenna Array With a Modified Parabolic Reflector

A millimeter-wave substrate-integrated waveguide (SIW) antenna with the ability of generating 2-D steerable large depth-of-field beam is presented in this article. First, a transverse antenna topology feeding with the series- and the parallel-network is employed to generate the limited-diffractive beam with large depth of field to overcome the problem that the conventional radial generator cannot steer its beam electronically. The proposed antenna is achieved by combining a modulated leaky-wave slot array antenna with a modified multibeam SIW parabolic reflector. The modulated leaky-wave slot array with stepped-width is designed to able to steer the limited-diffractive beam in the horizontal dimension with the frequency, which validates the frequency scanning feasibility of the limited-diffractive beam. Then a modified SIW parabolic reflector with matching loads is used to feed the modulated leaky-wave SIW slot array antenna to generate multiple limited-diffractive beams in the vertical dimension. A large depth of field of about 43λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is achieved of the central limited-diffractive beam. The measurements are in good agreement with the simulated results.

5G beam-steering 2×2 butler matrix with slotted waveguide antenna array

In this research paper, substrate integrated waveguide (SIW) was proposed as a technique by realizing bilateral edge walls to produce a compact 5G beam-steering antenna at 24 GHz. The beam forming network is produced using SIW directional coupler perform as 2×2 Butler Matrix (BM) fed with SIW slotted waveguide antenna array. The output signal is steered from -29 degrees and +29 degrees when the signal is fed to the respective input ports. If one of the input ports is fed, the signal is evenly distributed between the adjacent output ports with 90 degree constant phase shift. The compact size of directional coupler was designed by longitude slots on the surface of SIW substrate with bandwith of 16.85% at the operating frequency. The proposed antenna produce gain of 6.34 dB at operating frequency and the promising outcome of the beam steering make proposed design suitable for 5G communications especially with tracking capabilities.

A Sidelobe Level Reduction Method for mm-Wave Substrate Integrated Waveguide Slot Array Antenna

A new method of sidelobe level (SLL) reduction for a substrate integrated waveguide (SIW) slot array antenna is presented. In this method, amplitude distribution is assigned to the slots by tapering the SIW width. The SIW with tapered width can be efficiently manufactured by varying the position of the side-wall vias. In this letter, the new method is verified on a 12-element SIW slot array antenna operating at 94 GHz to achieve SLL around –30 dB. The antenna design procedure as well as simulation and measurement results are presented.

Proactive Conformal Antenna Array for Near-Field Beam Focusing and Steering Based on Curved Substrate Integrated Waveguide

The quadratic phase distribution on the antenna aperture is necessary to produce a near-field-focused (NFF) beam. The generation, as well as the steering of the quadratic phase distribution, is difficult for a series-fed NFF array antenna, especially for a large-aperture application. This is because the phase control capability of the planar series-fed beam-forming network is limited. In this paper, a curved substrate integrated waveguide (SIW) is employed as the feeding carrier to enhance the amplitude and phase control capability. The spatial placement of the SIW slot array antenna can be sufficiently used to synthesize the desired NFF beam. As examples, two kinds of proactive conformal SIW NFF slot array antennas, working in the standing-wave mode and the leaky-wave mode, have been developed. Both of them have the ability to generate the high-quality NFF beam. In addition, the proactive conformal SIW leaky-wave slot array antenna has the stable focal height over a wide steerable range. After careful analysis and design, these two kinds of antenna arrays are fabricated and proactively conformal to 3-D-printed frameworks with the desired shape. The theoretical analysis and simulated results are verified by experimental results.

Dual-Band Substrate-Integrated Waveguide Leaky-Wave Antenna With a Simple Feeding Way

A dual-band leaky-wave antenna (LWA) based on substrate-integrated waveguide (SIW) is presented in this letter. The proposed antenna consists of two back-to-back slotted SIW arrays fed by two strip lines, which can realize frequency-controlled scanning beams in two bands. The top SIW slotted array working in the low-frequency band radiates scanning beams in the upper-half free space, and the bottom array for the high-frequency band radiates scanning beams in the lower-half free space. The proposed LWA can radiate scanning beams from near broadside to the endfire in two different bands. The realized gains can get 12.9–17.1 dBi in the low band (8.2–9.4 GHz) and 15.9–20.1 dBi in the high band (13.2–15.2 GHz), respectively. The measured results of the fabricated prototype confirm the design theory and simulated results.

A Dual-Band Shared-Aperture Antenna With Large Frequency Ratio, High Aperture Reuse Efficiency, and High Channel Isolation

The operating frequency of future communication systems will cover unlicensed millimeter-wave bands as well as existing microwave bands. Large frequency ratio antennas that can be applied to both frequency bands simultaneously and maintain the high isolation between the two channels are difficult to design. This paper presents a new design of dual-band shared-aperture antenna based on the concept of structure reuse. The antenna consists of a patch antenna working at 3.5 GHz and a 12 × 12 substrate integrated waveguide (SIW) slot array antenna working at 60 GHz. The frequency ratio of this shared-aperture antenna is 17. In this design, the overall structure of the SIW slot array antenna is employed as the radiator of the patch antenna. With this new scheme, the high aperture reuse efficiency can be achieved. Meanwhile, the millimeter-wave antenna based on the SIW technology has the high-pass nature to reject the lower frequency signal. A compact microstrip resonant cell that acts as a low-pass filter is connected in series on the feedline of the microwave antenna to suppress the upper frequency signal. Thus, the channel isolation between the patch and the SIW slot array antennas can be more than 130 dB at 3.5 GHz and 65 dB at 60 GHz.

A High-Gain Sparse Phased Array With Wide-Angle Scanning Performance and Low Sidelobe Levels

This paper introduces the concept of the sparse array into the design of a wide-angle scanning phased array to obtain the low sidelobe level (SLL). The adopted array element is a half-mode substrate integrated waveguide slot array, which can radiate a high-gain and wide-beam pattern in the E-plane. A 16-element phased array with an optimized non-periodic array element arrangement, which is obtained by a semi-full-wave simulation-based synthesis method, is designed and studied. Compared with two periodic arrays with the same array element and element number, the sparse one exhibits the advantage of low SLL. Besides, the designed phased array has an ultra-low profile of only about $0.017\lambda _{0}$ . A prototype is fabricated and measured, and measured results show that the proposed array can scan its main beam from −70° to +70° with a realized gain higher than 18.2 dBi and peak SLL lower than −15 dB.

Design of a Low-SLL SIW Slot Array Antenna With a Large Declination in $Ka$ -Band

A small-size large-declination longitudinal slot array antenna based on substrate integrated waveguide (SIW) technology was proposed. Compared with the conventional SIW slot array, the proposed antenna achieves a larger declination and a lower SLL. The antenna is mainly composed of three parts, a dielectric substrate, a coaxial port, and a matched load. The antenna contains 13 radiation slots, and the adjacent slot spacing is greater than half of the waveguide wavelength, so the main beam is biased towards the load. To achieve low sidelobe levels (SLL), the amplitude distribution of the 13 slots is based on Taylor synthesis of SLL = -25 dB. The antenna was processed and measured. From the measured results, the antenna achieved a beam declination of 26° and a SLL below -20 dB from 35.2 to 35.8 GHz. With the same number of slots, the length of the slot array of the SIW structure is only 44.8% of the length of the standard metal hollow waveguide. Based on the performance achieved, the SIW slot antenna is an excellent candidate for carrier conformal and large declination applications.

A new double‐sided substrate‐integrated waveguide slot array antenna for 5G applications

AbstractA double‐sided substrate‐integrated waveguide (SIW) slot antenna with stripline feed, as 4‐by‐4 SIW slot array antenna, operating in millimeter‐waves bands is proposed. The whole antenna and feeding system are fabricated on a single substrate with 2 dielectric layers and 3 copper layers, which takes some advantage, such as, small size, low profile, low cost, and 2 radiation direction propagations. The design process and experimental results are presented. The prototypes can be used in dual band frequency ranges, 25 and 28 GHz, with 8 dBi gain and 63° for half power beamwidth in both sides, front and back antenna sides, and 2 GHz bandwidth. Thus, this component can be applied for 5G indoor environments.

Metasurface-Based Shared-Aperture 5G &lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;${S}$ &lt;/tex-math&gt; &lt;/inline-formula&gt;-/&lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;${K}$ &lt;/tex-math&gt; &lt;/inline-formula&gt;-Band Antenna Using Characteristic Mode Analysis

An ${S}$ -/ ${K}$ -band metasurface-based antenna with a shared aperture is proposed for 5G applications. The metasurface is designed with the dual-band characteristics for two antennas to work in the same aperture without interference. Based on the characteristic mode analysis, $3\times 3$ metasurfaces are proposed for the ${S}$ -band radiation. To radiate the ${K}$ -band electromagnetic wave without blocking, the metasurfaces are discretized by the subcell of a square ring and an inner square patch to achieve a frequency selective function. Then, as an example, the microstrip-fed slot is used to drive the metasurfaces at the ${S}$ -band, while an $8\times 8$ substrate integrated waveguide slot array antenna between microstrip and metasurface is designed at the ${K}$ -band. The measurement shows the 10 dB return loss bandwidths of 23.45% and 4.8% and the realized gain of 7.52–10.88 and 21.3–22.4 dBi over the ${S}$ -band (3.2–4.05 GHz) and the ${K}$ -band (25.22–26.46 GHz), respectively.

Optimization and Implementation of SIW Slot Array for Both Medium- and Long-Range 77 GHz Automotive Radar Application

In this communication, a novel substrate integrated waveguide slot array with flat-shoulder-shaped radiation pattern is introduced for both 77 GHz automotive medium-range radar and long-range radar applications. The operational principle of the antenna is introduced, while the synthesis of the desired radiation pattern is facilitated by a mixed optimization method, including nonlinear fitting and aggressive space mapping. Experiments are carried out and the measured peak gain of the proposed array is 21.7 dBi. The demonstrated antenna presents to be an excellent candidate for 77 GHz automotive radar application.

SIW Rotman Lens Antenna With Ridged Delay Lines and Reduced Footprint

A dual-layer Rotman lens with reduced footprint and wide field of view is introduced here in substrate integrated waveguide (SIW) technology in the 24-GHz band. Both layers are connected by a high-efficiency transition made by an SIW integrated reflector and several coupling vias. The delay lines of the Rotman lens are implemented in ridged waveguides for compactness and broadband operation over a wide angular range, and the radiating part is an SIW slotted waveguide array made of 15 resonant waveguides. Design guidelines and performance are provided for the transition and the ridged delay lines. Experimental results show very good scanning performance over an angular sector of ±48°.

In brief

PAGE 741 A low-loss hollow-core photonic crystal fibre (HV-PCF) which operates in the terahertz (THz) frequency range is proposed by researchers from Bangladesh. The HV-PCF has a total diameter of 2.75 mm and consists of a regular hexagonal lattice structure with four air-hole rings and a larger central air-hole. The fibre has an extremely low effective material loss of 0.0122 cm−1 obtained at 2.125 THz with 94% of air-core power fraction. PAGE 704 French and Canadian researchers present an air-filled substrate integrated waveguide (AFSIW) slot array antenna, for use in high-performance substrate integrated millimetre-wave systems. When compared with the conventional dielectric-filled SIW, the AFSIW design displays a narrower beam (44% and 18% narrower H- and E-plane half-power beamwidth), and enhanced efficiency (improved by 1.6%). Cross-section of hexagonal lattice structure of crystal fibre able to operate in THz range. PAGE 726 A balanced ring hybrid with arbitrary power division ratio was fabricated by embedding four half-wavelength microstrip lines in the single-ended ring hybrid. The design from China, displays arbitrary differential-mode power division, good common-mode suppression and low insertion loss and high realisable maximum k2. Air-filled substrate integrated waveguide slot array antenna. PAGE 717 An image-compressive sensing preprocessing algorithm is proposed by researchers from China. The collaboration reduced rank (CRR) algorithm is based on nonlocal sparsity and a nonlocal low-rank regularisation reconstruction algorithm (NLR-CS). The method outperforms current compressive sensing reconstruction methods in peak-signal-to-noise and visual perception. Photograph of balanced ring hybrid with arbitrary power division. PAGE 702 Researchers from Korea present a method for supressing surface waves on a microstrip antenna array at the millimetre-wave frequency. Complimentary split ring resonator (CSRR) structures are etched on the ground plane of a 10×2 microstrip array. Measured results show a gain improvement of 2.5 dB and a side lobe level reduction of 3.5 dB. Its light weight, low volume and thin profile make it suitable for radar applications. Image compressive sensing preprocessing algorithm proposed. Microstrip array antenna with etched on CSRR structures for supressing side waves.