Substrate Integrated Waveguide Research Articles

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.

Frequency-Tunable SIW Band-Reject Filter with Increased Fundamental Mode Bandwidth for Spectrum Underlay Cognitive Radio

This paper presents the design of a frequency-tunable substrate-integrated waveguide (SIW) band-reject filter, specifically for spectrum underlay cognitive radio operation. The proposed filter has a simple tuning circuit but provides a wide frequency tuning range from 2.9 to 4.4 GHz (41%). The second resonant mode has been suppressed using a simple quadrature coupling; hence, the fundamental mode bandwidth of the filter has been increased from 2.08 GHz to 3.36 GHz. Due to its wide tuning range, simple tuning circuit, and increased fundamental mode bandwidth, the proposed filter is greatly important in underlay cognitive radio construction. The second-order filter has also been developed, and its performance is analyzed with both simulation and measurement. It gives a tunable bandwidth of 41%, an insertion loss of more than 10 dB, and a fundamental mode bandwidth of 3.36 GHz. The filter performance is also analyzed after connecting it to the standard horn antenna. Finally, from the total efficiency plots, it has been concluded that the proposed filter achieves all the above advantages with a low-lossy nature.

Leaky wave antenna loaded complementary elements with dual-stopband suppression

Abstract In this paper, a periodic leaky wave antenna (PLWA) using complementary elements is proposed. The complementary elements of the transverse slot (horizontal magnetic current) and the monopole pairs (vertical electric current) in the substrate integrated waveguide (SIW) is employed as the radiation element, which can simultaneously suppress closed stopband β0p=π and open stopband (OSB) β-1p=0 to enhance the forward scanning of the LWA. Additionally, the gain and cross-polarization of the element are improved due to the loading of the monopole pairs. The LWA achieves forward and backward scanning from -73° to 10° when operating at the n=-1 spatial harmonic (SH), with corresponding gains of 11.5 to 15.4 dBi. When operating at the n=0 SH, it achieves forward scanning from 58° to 72°, with corresponding gains of 5.2 to 7.5 dBi. Moreovere, due to the element and its symmetrical structure, the cross-polarization within the entire operating frequency range is less than -35 dB. The design concept is validated through processed, fabricated, and tested.

Antenna Array Design Based on Low-Temperature Co-Fired Ceramics

With the continuous development of wireless communication technology, the frequency band of 6G communication systems is moving towards higher frequencies such as millimeter waves and terahertz. In such high-frequency situations, wireless transmission requires antenna modules to be provided with characteristics of miniaturization, high integration, and high gain, which presents new challenges to the development of antenna technology. In this article, a 4 × 4 antenna array using multilayered low-temperature co-fired ceramic is proposed, operating in W-band, with a feeding network based on substrate-integrated waveguide, and an antenna element formed through the combination of a substrate-integrated cavity and surface parasitic patches, which guaranteed the array to possess the advantages of high integration and high gain. Combined with the substrate-integrated waveguide to a rectangular waveguide transition structure designed in the early stage, a physical array with a standard metal rectangular waveguide interface was fabricated and tested. The test results show that the gain of the antenna array is higher than 18 dBi from 88 to 98 GHz, with a maximum of 20.4 dBi.

Miniaturized leaky-wave antenna with backward-to-forward beam scanning and suppressed open stop-band based on substrate-integrated plasmonic waveguide

This work presents a theoretical design and experimental demonstration of a novel miniaturized leaky-wave antenna (LWA) using composite waveguide based on substrate-integrated plasmonic waveguide (SIPW). The SIPW is designed by embedding hybrid dual spoof surface plasmon polariton (SSPP) structure into a three-layer substrate integrated waveguide (SIW). Due to the slow-wave effect of SIPW, the proposed miniaturized composite waveguide forms slowed phase velocity and decreased lower cutoff frequency. To excite backward-to-forward beam scanning mode and suppress the open stop-band, an asymmetric sinusoidal modulated structure is introduced to the surface of the composite waveguide. The experimental results indicate that the proposed SIPW-based LWA can achieve continuous beam scanning from the backward to the forward direction within the bandwidth of 10.6-13.7 GHz, passing through the broadside at 11.6 GHz.

A design of compact wideband substrate integrated waveguide fractal koch surface slot antenna for Ka$$ Ka $$‐band applications

SummaryThis article analyses a substrate integrated waveguide (SIW) fractal koch surface (FKS) slot antenna performance for Ka‐band applications. This FKS slot shape is obtained by modifying the conventional rectangular slot with the first iteration of the FKS method. The resultant FKS slot behaves as a radiator in the provided space. A single‐ and two‐element FKS slotted SIW antenna characteristics are analysed on a 20 mil thick RT/Duroid 5880 substrate and compared with the conventional rectangular slot. The proposed antenna with dimensions mm3 achieves an impedance bandwidth from 27.4 to 32.1 GHz with a fractional bandwidth of 15.79% and achieves a gain of 8.3 dBi in broadside direction by improving space filling factor in SIW structure. The prototype of the SIW‐fed FKS slotted antenna array measurement results is satisfactory with the simulation results.

A compact, low‐loss, and wide passband ratio substrate integrated waveguide triplexer based on complementary split ring resonators for multiband applications

SummaryIn this paper, a design of a substrate‐integrated waveguide (SIW) triplexer with improved low‐loss performance, passband ratio, and compactness based on the complementary split ring resonator (CSRR) structure is presented. The proposed triplexer operates at three passbands of 6, 8, and 10 GHz that correspond to the passband ratios of 1.33 and 1.67. By appropriately designing square CSRRs on the surface of the SIW structure, the low‐loss and compact resonator filters below the cut‐off frequency of the SIW at each operation frequency can be realized. The wide passband ratio is obtainable by adjusting the dimensions of the T‐junction. The measured results show the minimum insertion losses of 1.5, 1.4, and 1.9 dB at 6, 8, and 10 GHz, respectively. In addition, the minimum measured return losses are −9.33, −11.3, and −12.4 dB at the corresponding three passbands. The measured isolation between output ports is better than −17 dB in the frequency range from 5 to 11 GHz. The measured results agree well with simulations which are conducted by the CST Microwave Studio simulator. The proposed triplexer is designed on a cost‐effective RO4003C substrate with a compact size of 35 25 mm2

Miniaturized bandpass metamaterials filters using hybrid plasmonic waveguide and defected surface structures

In this paper, we present a novel approach for designing single-/multiple-band bandpass filters (BPFs) using a hybrid metamaterials approach, incorporating substrate integrated waveguide (SIW), spoof surface plasmon polariton (SSPP), and defected surface structures (DSSs) technologies. The substrate-integrated plasmonic waveguide (SIPW) is constructed by embedding a hybrid dual SSPP into a three-layer SIW. The SIPW demonstrates a reduced phase velocity and a lowered lower cutoff frequency, extracted from the slow-wave dispersion relationship. Initially, the SIPW-based single-band metamaterial BPF demonstrates miniaturized size and broadened bandwidth. Furthermore, by loading a pair of complementary electric-inductive capacitive (ELC) resonators consisting of DSSs and adjusting their symmetry properties and geometric parameters, multiple BPFs from 1 to 3 are realized. To validate the proposed designs, three prototypes are fabricated and measured. The results demonstrate good filtering performances of proposed metamaterial BPFs, featuring high reflection loss (S11 < −10.5 dB) and a high level of out-of-band rejection exceeding 25 dB between multiple passbands.

Substrate integrated waveguide-based self-triplexing antenna-sensor

In this paper, a Substrate Integrated Waveguide (SIW) based self-triplexing antenna-sensor is introduced. The proposed structure can act as a sensor for concurrent detection of three chemical materials. Further, it can be used as a self-triplexing antenna for simultaneous operation at three different frequencies. To that end, initially, a half mode circular SIW cavity is designed. Then, it is divided into three parts. In each part, the position of maximum electric field is determined and subsequently, three holes are located in the positions for material insertion. Finally, considering the vacuum as the inserted material for each hole, each cavity is adjusted to operate at its operation frequency (4.8, 5.8, and 6.6 GHz). Altering the permittivity of the objects inserted in the holes, the resonant frequencies are changed and consequently the type of material is determined. The simulated and measured results validated the performance of proposed antenna-sensor as well. In all the frequency bands, the reflection coefficients as well as mutual coupling among ports are below −20 dB. It should also be expressed that such an SIW structure with the capability of sensing and propagation is provided for the first time.

A U-band cascaded quadruplet quartz glass SIW filter based on double row vias coupling window

A U-band Substrate Integrated Waveguide (SIW) Cascaded Quadruplet (CQ) filter is designed based on low-cost quartz glass planar integrated circuits process with limited depth-to-diameter ratio and via spacing, which challenge the control accuracy of coupling coefficients. To address this issue, a double-row vias coupling structure control strategy is proposed to enhance the precision of coupling coefficient control. Cascaded quadruplet topology based on the proposed coupling structure with asymmetric coupling window is designed to improve the passband selectivity and harmonic suppression. The filter exhibits −3dB relative bandwidth of 4.6 % (1.94 GHz) at a central frequency of 42.2 GHz, insertion loss of 4.2 dB and rectangular coefficient (−20 dB BW/−3dB BW) of 1.47.

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.

Contactless AF-SIW phase shifters based on periodic structures at mmWaves

This document presents different phase shifter designs implemented in contactless air-filled substrate-integrated waveguide (CLAF-SIW) technology. The phase shifters are based on unit cells that avoid leakage losses in the assembled layers and produce the desired phase shift along the waveguide. The unit cells are represented by waveguides whose lateral walls have double-mushroom structures, and phase-shifting elements are in their propagation zone. The proposed phase-shifting elements are integrated cavities, integrated cavities with patches, and integrated cavities with mushroom-like patches. Transitions are needed to match impedances between the waveguides loaded with phase-shifting elements and a reference CLAF-SIW. Other transitions are designed to measure the prototypes, from coplanar waveguide to SIW and SIW to CLAF-SIW. Finally, some prototypes are manufactured to provide an experimental validation of the proposed phase-shifting elements. Good agreement is obtained between the simulated and measured results for all the CLAF-SIW phase shifters in the frequency range between 30 and 50 GHz.

Characterization of Unit Cells of a Reconfigurable Intelligence Surface Integrated with Sensing Capability at the mmWave Frequency Band

Integrated sensing and communication (ISAC) is emerging as a main feature for 5G/6G communications. To enhance spectral and energy efficiencies in wireless environments, reconfigurable intelligent surfaces (RISs) will play a significant role in beyond-5G/6G communications. Multi-functional RISs, capable of not only reflecting or transmitting the beam in desired directions but also sensing the signal, wirelessly transferring power to nearby devices, harvesting energy, etc., will be highly beneficial for beyond-5G/6G applications. In this paper, we propose a nearly 2-bit unit cell of RISs integrated with sensing capabilities in the millimeter wave (mmWave) frequency band. To collect a very small fraction of the impinging signals through vias, we employed substrate integrated waveguide (SIW) technology at the bottom of the unit cell and a via. This enabled the sensing of incoming signals, requiring only a small amount of the impinging signal to be collected through SIW. Initially, we utilized Floquet ports and boundary conditions to obtain various parameters of the unit cells. Subsequently, we examined 1 × 3-unit cells, placing them on the waveguide model to obtain the required parameters of the unit cell. By using the waveguide and 1 × 3-unit cell arrays, the sensing amount was also determined.

Hamiltonian deep neural network optimized with pelican optimization algorithm-fostered substrate-integrated waveguide antenna design for 5G

Hamiltonian deep neural network optimized with pelican optimization algorithm-fostered substrate-integrated waveguide antenna design for 5G

A miniaturized and low-loss Q-band SIW bandpass filter based on evanescent-mode in wafer-level packaging process

This paper presents a miniaturized Q-band substrate integrated waveguide (SIW) bandpass filter (BPF) on a silicon-based wafer-level packaging (WLP) process. By incorporating capacitive quasi-coplanar waveguide (CPW) feeding structures and complementary split-ring resonators (CSRRs), the SIW operates in an evanescent-mode below the lower cutoff frequency and then achieves miniaturization. The efficient conversion of wave-modes, mutual excitation among multiple capacitive structures, and extremely short transmission paths, collectively resulting in the proposed BPF exhibiting low insertion loss. Furthermore, the area of fabricated filter has been reduced by 88.96 % compared to the requirement of the cutoff frequency. The measured results show that the minimum insertion loss is 1.24 dB, the return loss is better than 15 dB, and the 3 dB passband covers from 29.6 to 47.8 GHz (FBW is 47 %). These results indicate that, the proposed filter effectively solve the issues of large areas in SIW filters and high losses in silicon-based integrated or packaging processes.

2D leaky-wave antenna with controlled direction of radiation in the azimuthal plane

Abstract This paper presents a two-dimensional (2D) metasurface antenna array composed of mushroom cells coupled by thin slots in the top metallization. The antenna is fed through power dividers designed in substrate-integrated waveguide technology. The antenna structure is therefore designed in a fully up-to-date integrated version. The array shows beam steering in the azimuthal plane controlled by signal amplitudes fed into particular ports at the edges of the matrix. The main advantage of this antenna is no need to use phase shifters applied in standard 2D antenna arrays. Two antenna versions have been designed, fabricated, and experimentally tested. The beam can be steered within 360° (90°) in azimuth. The steering of the beam in elevation from backward to forward directions within 40° is done by changing frequency from 21 up to 23.8 GHz. This interval is reduced to 30° by exciting the antenna simultaneously at two adjacent ports at the same amplitude.

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.

A Multifunctionality Reconfigurable HMSIW Filter by Using EBG Structure and Diodes for C/X-Band Application

This letter presents a multifunctionality reconfigurable substrate-integrated waveguide (SIW) filter embedded in a microstrip line. The proposed filter used an electromagnetic bandgap structure (EBG) to compact the size and improve the electromagnetic features. The SIW filter consists of a three-cell EBG with metallic circular-shaped connected to the ground through cylindrical vias. Firstly, the base SIW structure offers a wide passband filtering response, and then, to obtain selective passband, wide band rejection, and controllable resonance frequencies, a three-cell EBG along with four diodes has been attached. The filter is designed and printed on a Rogers 4003 substrate with a thickness of 1 mm and is experimentally validated for functionalities operated at three modes with an average 3 dB bandwidth of 115 MHz in each frequency. In addition to that, two transmission zeros (TZ) have been produced in the upper band frequency. The filter’s response is also tunable by turning the diode off or on and changing the main parameters of EBG, the gab, and the position between cells. The study explores resonance frequency alterations in a three-state system of on/off. By eliminating or diminishing specific modes, and incorporating diodes, distinct resonance behaviors are observed. Moreover, shifting frequency resonance in a multiparameter system has been investigated. Increasing B1 induces a significant shift to lower values, while an increase in D1 leads to a decrease in the first and second resonance frequencies and an upward shift in the third. The designed filter has been fabricated and tested to compare and confirm simulated responses. Simulation and measurement results are in good agreement. The S-parameters of measured results gained a good response (&gt;15 dB) within the passbands and stopbands and an insertion loss of 1.5 dB suitable for 5G and Wi-Fi systems.

A dual‐wideband 5G antenna with dual polarization in the sub‐6 GHz band and 2 × 2 MIMO function in the 28‐GHz band

AbstractA novel aperture‐shared dual‐wideband 5G antenna with dual polarization in the sub‐6 GHz band and multi‐input multi‐output (MIMO) function in the 28‐GHz band is presented in this work. A dual‐polarized megnetoelectric dipole (ME‐dipole) with wide bandwidth is introduced in the sub‐6 GHz band. Based on the partial structure reuse method, four 2 × 2 substrate integrated waveguide (SIW) cavity‐backed patch arrays are integrated into the electric dipole structure of the ME‐dipole to construct a 28‐GHz 2 × 2 MIMO system. Two high‐order SIW cavity modes that cooperate with patch modes are used to enhance bandwidth in the 28‐GHz band. For demonstration, a prototype of the proposed antenna was fabricated and measured. The simulated results are in good agreement with the measured results, showing wide bandwidths of 39.6% and 10.85% in the sub‐6 GHz and the 28‐GHz bands, respectively. In addition, excellent measured in‐band and cross‐band isolations of over 44.4 dB and 45.2 dB are obtained, respectively.

Dual-Band Large-Frequency Ratio Power Divider Using Mode Composite Transmission Line for 5G Communication Systems

In this paper, a novel kind of mode composite transmission line (MC-TL) is proposed, and a dual-band power divider with a large frequency ratio using this novel MC-TL for 5G communication systems was developed. The proposed MC-TL was developed using spoof surface plasmon polaritons (SSPPs) and a corrugated substrate-integrated waveguide (CSIW) transmission line, which supports both a surface plasmon mode and TE10 mode, independently. The surface plasmon mode operates in the grooves of the surface metal layer, while the TE10 mode works in the substrate between two metal layers. These two parts can transmit different modes at independent frequencies. This structure can be used in dual-band transmission lines with a high frequency ratio. The characteristics and design of the MC-TL (SSPPs and CSIW) are analyzed and illustrated. The MC-TL was fabricated and measured to demonstrate its performance. Moreover, based on the proposed MC-TL, a dual-band power divider with a large frequency ratio (operating at 3 GHz and 28 GHz simultaneously) was also designed and fabricated. It can cover the frequency of a fifth-generation communication system perfectly. The measured outcomes align closely with the simulated results, demonstrating robust agreement and showcasing excellent transmission capabilities.