Substrate Integrated Waveguide Research Articles

A compact self-quintuplexing antenna by HM-SIW cavity

Abstract This paper presents a novel compact self-quintuplexing antenna using a half-mode substrate-integrated waveguide cavity to implement multi-operation wireless services. The proposed antenna design incorporates five triangular protrusions of different dimensions, assembled with SIW to function as the radiating elements. Each radiator supports the one-eighth mode of the SIW cavity. The resonance frequencies of radiators are 3.63, 4.44, 5.23, 6.21, and 7.05 GHz. Each radiator operates at a distinct frequency due to the differing dimensions and is independently driven by 50 Ω microstrip lines. The measured reflection coefficients and isolation among any two ports are less than −10 dB and better than 23.6 dB, respectively. The measured gains at their respective resonant frequencies are 5.66, 4.84, 5.03, 7.08, and 6.59 dBi. The front-to-back ratio is better than 8.7 dB in each band. The difference of co-to-cross-polarization is greater than 19.3 dB.

Compact dual-band filter using hybrid transition-free spoof surface plasmon polaritons and substrate integrated waveguide

In this paper, a new hybrid transition-free spoof surface plasmon polaritons (SSPPs)-substrate integrated waveguide(SIW) unit is used to design a compact dual-band filter. Benefiting from the combination of the H-shaped unit and the bilateral T-shaped unit of the proposed hybrid unit, the inherent two-stage wave vector matching is provided to achieve momentum and impedance matching. Thus, the proposed transition-free SSPPs-based filter does not require SSPPs transition units, making the circuit size reduction largely. Moreover, the high-order mode (Mode 1) of the transition-free SSPPs transmission units will not be suppressed by the stopband between the fundamental mode (Mode 0) and Mode 1 of transition-free SSPPs transition unit, making it possible to design a dual-band filter based on Mode 0 and Mode 1. In addition, the cutoff frequency of the filter can be controlled by the geometric size of the hybrid transition-free SSPPs-SIW unit. To verify the design theory, a compact dual-band filter with operating frequencies of 4.4 GHz − 5.6 GHz and 9.0 GHz − 9.6 GHz is designed and fabricated. The simulated results are in good agreement with the test results, indicating the feasibility of the proposed structure and design method.

High-Order Resonating Cavity-Backed Slot Antenna Array Based on Contactless Air-Filled Substrate-Integrated Waveguide and Transition to Inverted Grounded Coplanar Gap Waveguide

High-Order Resonating Cavity-Backed Slot Antenna Array Based on Contactless Air-Filled Substrate-Integrated Waveguide and Transition to Inverted Grounded Coplanar Gap Waveguide

A wideband circularly polarized filtering dielectric resonator antenna array based on magneto-electric currents combination

ABSTRACT A circularly polarized (CP) filtering dielectric resonator antenna (DRA) array is proposed based on the magneto-electric currents combination (MECC) method in this paper. The array consists of four rectangular DRAs, four hook-shaped electric dipoles (HSED), and two layers of substrate integrated waveguide (SIW) cavities. The electric current (EC) on the HSED is excited by the slot aperture of the SIW cavity, and the equivalent magnetic current (MC) is simultaneously generated with HSED in the DRA. Based on the surface current regulation, the EC and MC are adjusted to achieve appropriate amplitudes and phases, thereby realizing wideband CP radiation. The filtering function is realized with the high-pass characteristics of the SIW and the effective suppression of the higher-order modes in the resonance cavity. Due to the presence of an air gap between the DRAs and HSED, the higher modes of the DRA are designed for bandwidth enhancement. The prototype of the DRA array has been fabricated and measured, exhibiting a relative bandwidth of 26.1% and an axial ratio bandwidth of 17.77%, with radiation nulls present at either side of the passband. With the advantages of wide bandwidth and high gain, the proposed DRA array can be applied to satellite communications.

Compact and Wide-Stopband Bandpass Filter Using Hybrid Shielded EMCSIW and CSRR Resonators with a Mixed Electromagnetic Coupling Scheme

This paper presents a bandpass filter (BPF) exploiting hybrid shielded eighth-mode circular substrate-integrated waveguide (SD-EMCSIW) and complementary split ring resonator (CSRR) resonators. The proposed BPF leverages the SD-EMCSIW resonator with a 45-degree angle to create a second-order BPF with a mixed electromagnetic coupling scheme. Detailed analyses of the related electromagnetic characteristics and operating mechanisms have been performed. In order to further reduce the occupied area, the CSRR structures are embedded into the SD-EMCSIW resonators. Meanwhile, extra metallic via-holes are implemented to enhance the upper-stopband performance. A transmission zero (TZ) of the second-order BPF can be placed on either the left or right side of the passband and can be flexibly adjusted. To validate the design concept, a second-order hybrid SD-EMCSIW and CSRR BPF was designed, simulated, fabricated, and measured as a specific example. The prototype operates at a center frequency f0 of 8.3 GHz with a 3 dB fractional bandwidth of 8.1%. Two transmission zeros are located near the right passband. The upper-stopband rejection reaches up to 15 dB at 2.85 times the center frequency f0. Both the simulated and measured results show satisfactory agreement. Meanwhile, the overall size of the proposed hybrid SD-EMCSIW and CSRR BPF is 13.5 mm × 13.0 mm (0.37λ0 × 0.36λ0), featuring a compact physical dimension in the filter design.

Substrate integrated waveguide differential antenna for full duplex applications

Abstract This paper presents a substrate-integrated waveguide (SIW) differential antenna for full duplex applications. The proposed antenna consists of two square SIW cavities named as outer and inner. The inner cavity is nested into the outer cavity. The outer cavity is differentially excited with a pair of coaxial feed lines, while the inner square patch is orthogonally excited with another pair of differential coaxial feed lines. This orthogonal feeding arrangement results in high isolation between the differential ports. The modified hybrid TE130/310 mode of the outer cavity radiates through a pair of arc-shaped slots at 9.35 GHz, while the TM01 mode of the inner square patch is responsible for the radiations at 8.65 GHz. The proposed antenna prototype is fabricated and measured for validation. Moreover, the designed antenna has a front-to-back ratio better than 22 dB and measured maximum gain values of 6.1 dBi and 7.6 dBi at 8.65 GHz (Port 2 ON) and 9.35 GHz (Port 1 ON), respectively.

Multilayer substrate integrated waveguide six-port junctions with embedded resistive films

Abstract This article deals with multilayer substrate integrated waveguide (SIW) six-port junctions with embedded carbon resistive films. SIW six-ports usually employ reactive power dividers, which degrade the amplitude and phase balance when the six-port is terminated with mismatched power detectors. The associated impairments are studied and two SIW six-port junctions with improved isolation and output matching are designed for K-/Ka-band applications to overcome these limitations. The proposed designs differ with respect to the configuration of the output ports making the underlying six-port topology applicable for different layout requirements. Measurements of the fabricated components validate the concept. The six-ports are compact, fully shielded and can be integrated in multilayer printed circuit boards.

A beam-reconfigurable probe-fed mm-wave SIW slot array antenna using cavity-backed U-slot SIW switch

ABSTRACT A beam-reconfigurable millimeter-wave (mm-wave) antenna is proposed, constructed with a dodecagonal substrate integrated waveguide (SIW) structure and a cavity-backed U-slot SIW switch. The SIW switch consists of a U-shaped slot in the ground plane, a p-i-n diode, and a pair of metallic vias, primarily operated by controlling the impedance of the U-shaped slot. Six SIW switches are employed to enable six-beam switchable reconfiguration. Correspondingly, six 4 × 4 SIW slot subarrays are equiangularly arranged along the periphery of the dodecagonal substrate, acting as the main radiators. By carefully controlling the excitation phase and magnitude of the slot elements in the subarrays, a tilted beam of approximately θ = 19° can be produced in measurement with switchable reconfigurable beams 1‒6 steering along the azimuth plane at discrete angles of approximately ϕ = 90°, 150°, 210°, 270°, 330°, and 30°, respectively. The measured results indicate that the overlapped impedance bandwidth (|S11|<-10 dB) of the proposed antenna is across 25.63‒26.08 GHz with a relative bandwidth of 3.7%. The measured antenna peak gains for beams 1‒6 can reach up to 8.0 dBi.

Highly selective filtering power divider using substrate integrated waveguide technique for radar applications

&lt;p&gt;&lt;span&gt;This article exhibits a filtering power divider designed with substrate integrated waveguide (SIW) technique, having the power dividing as well as filtering functionalities. In the design band-pass performance is realized by merging SIW structure having high-pass response and complementary split ring resonator (CSRRs) with parallel tank LC resonant response and the dumbbells shape defected ground structure (DGS) with high out of band rejection characteristics. The anticipated structure serves as both a power divider and a filter, it reduces both the cost and the size of the system. Structure is constructed and tested to confirm the design functionality. The measurement result shows the return loss of -25.94 dB with 3-dB fractional bandwidth of 2.85% at 14 GHz.&lt;/span&gt;&lt;/p&gt;

A Wideband Transition From Coaxial Line to Substrate-Integrated Waveguide

A Wideband Transition From Coaxial Line to Substrate-Integrated Waveguide

Miniaturized Substrate-Integrated Waveguide Bandpass Filter Using Symmetric Vertical Slots

A substrate-integrated waveguide (SIW) bandpass filter designed by introducing a vertical slot in the central metallic septum of the SIW is proposed in this paper. The input/output arrangement analysis and the stub variation in the port termination are also demonstrated, resulting in a wider bandwidth and better performance characteristics. The SIW bandpass filter (BPF) has a passband in the range of 18.23 GHz - 28.74 GHz depending on the stub variation arrangement with the central symmetric slot synthesized on a 0.5 mm thick planar RO 3003 substrate using a periodically arranged metal via holes. The proposed filter has excellent wide stopband rejection characteristics of -16 dB from 30 GHz to 40 GHz. Furthermore, the experimentally measured S-parameters of the filter are in good agreement with the simulated results; thus, the performance of the filter is validated.

A hybrid solar and RF energy harvester for applications of self-Powered wireless sensor nodes

A hybrid solar and RF energy harvester is proposed for applications in self-powered wireless sensor nodes. A planar slot antenna array backed by substrate integrated waveguide (SIW) cavity is produced for RF energy harvesting. A designed rectifier connected to the antenna array converts the received RF energy into DC energy. Solar cells are placed on the rest of the antenna array except slots, fully utilizing the array's surface. The solar cell coverage ratio reaches 87%. The measurement results indicate that under solar simulator illumination, the solar energy harvester has a short-circuit current of 15.7 A, an open-circuit voltage of 0.542 V, and a maximum output power of 5.81 W. Under the RF power density of 85.5 μW/cm2, the RF energy harvester reaches its peak power conversion efficiency (PCE) of 69%. All simulated and measured results are in good agreement, verifying the capabilities of the designed hybrid harvester.

Design and Analysis of Sierpinski Fractal Antennas for Millimeter‐Wave 5G and Ground‐Based Radio Navigation Applications

ABSTRACTThe paper describes compact fractal antennae combined with ground defected structures (DGS) and substrate integrated waveguide (SIW) techniques for enhancing resonate and multiband behavior concerning bandwidth, gain, and radiation in the desired mm‐wave region. Based on the proposed antennae, multiple good notches over wide bands depict a good radiation pattern. The antennae's ultra wide bandwidths (UWB) are 16, 16, and 11.4 GHz concerning resonant frequencies 26.34, 30.35, 34.5, 36.65 GHz; 25.8, 32.2, 35.3 GHz; 30.22, 37.68 GHz, of concerning antennae ant 1 (FA1), 4 (FA2), and 6 (FA3), respectively. The proposed antenna (FA3) with the SIW technique has a peak gain of 5.9 dBi and a peak front‐to‐back ratio of 20 dB, respectively. The proposed antennas are targeted to cover the practical contribution aspect, including advanced 5G bands support (24–40 GHz), broadband spectrum, frequency agility, low 3 dB beamwidth, interference reduction, and medical application suitability, respectively. The proposed antennae also cover the desired mm wave 5G region with different resonating notches over ultra‐wide bandwidth, such as n257, n258, n259, n260, and n261, and ground‐based radio navigation applications. Results are validated with vector network analyzer, spectrum analyzer, and power sensor in the presence of absorber, respectively.

Compact Substrate Integrated Waveguide Cubical Dielectric Resonator Antenna for fifth-generation applications

A comprehensive analysis of a wideband Cubical Dielectric Resonator Antenna is presented, specifically designed for 5G-NR wireless communication applications, focusing on the N257, and N258 frequency bands. This antenna exhibits symmetrical radiation patterns, a wider bandwidth, improved efficiency, and substantial gain characteristics. The design employs a low-loss substrate-integrated waveguide structure to enhance gain while reducing cross-polarization effects. This is accomplished through an innovative approach of establishing boundary conditions using copper wire stitching for vias, superseding the conventional soldering iron method, which guarantees minimal radiation leakage, compact dimensions, and reduced losses. The perforated dielectric resonator antenna possesses higher mode excitations, and implementing metallic strips on two resonator surfaces facilitates the simultaneous excitation of fundamental and higher-order modes, thereby yielding a broadband response. The overall dimensions of the antenna are 15.29 × 8.42 × 3.8 mm3(1.3×0.7×0.3)λ03, which facilitates a measured impedance bandwidth of 8.2 GHz, spanning from 24.4 to 32.6 GHz (28.7%), accompanied by a high gain of 8.1 dBi and efficiency levels reaching up to 94%. The prototype is constructed utilizing the standard printed circuit board technique, and simulation outcomes are derived using the High-Frequency Structure Simulator (HFSS).

Novel Multi-Band SIW Antenna with Filtering Function

In this paper, the basic structure of a quad-band substrate-integrated waveguide (SIW) antenna with filtering characteristics is proposed. The proposed antenna consists of a four-slot SIW and a single-probe feed. Despite having a single feed, it was able to independently control the four resonant frequencies. However, since a basic quad-band SIW antenna has three radiation null frequencies, the left skirt characteristics of f1 and the right characteristics of f4 were not good. To improve this, four pairs of vias and a pair of U-slots were introduced to add two radiation null frequencies to the lower part of f1 and the upper part of f4, respectively. This time, the parameters of the basic structure did not change, except for those of the added structure. The fabricated antenna operated at 3.9, 4.03, 4.2, and 4.3 GHz, and exhibited a radiation null below -15.6 dBi at 3.6, 3.95, 4.09, 4.27, and 5.07 GHz.

A compact low-profile substrate integrated waveguide wearable filtenna for 5G communication

We have proposed the design and synthesis of a compact, low-profile, flexible substrate integrated waveguide (SIW) wearable filtering antenna (filtenna) for 5 G communication, along with two parasitic resonator patches. We initially used a half-mode rectangular-shaped substrate-integrated (HMRSI) cavity as a resonating patch to minimize circuit size. The HMRSI cavity is located in close proximity to two parasitic truncated corner patches that serve as both the radiator and the final stage resonators, thereby optimizing filtering performance and expanding the operating bandwidth. The interaction of the parasitic patches with the HMRSI cavity produces one radiation null at the upper band-edges, while the corner truncation and notching on the parasitic patches with defected ground creates the other, enhancing the roll-off rate. Typical filter synthesis technology guides the design of the antenna. We have manufactured and measured an optimized prototype. The proposed flexible filtenna demonstrates excellent out-of-band selectivity, and its measurement aligns well with simulated ones, achieving an 8.2% fractional bandwidth (FBW), a maximum realized gain of 6.1 dBi, and a flat passband gain response. The proposed filtenna has also studied the human body and achieved a low specific absorption rate (SAR), which enables it to be an on-body wearable filtenna.

Miniaturized Multiband Substrate-Integrated Waveguide Bandpass Filters with Multi-Layer Configuration and High In-Band Isolation

This article presents a multiband bandpass filter structure with an in-line topology based on substrate-integrated waveguide (SIW) technology. A multi-layer configuration is employed to achieve circuit miniaturization. By constructing the coupling matrix, the coupling relationships among all resonators are quantitatively characterized, enabling the extraction of the theoretical frequency response and guiding circuit modeling and optimization. We designed and fabricated a third-order tri-band SIW filter and a third-order quad-band SIW filter, achieving a return loss of nearly 20 dB across all passbands. The close agreement between simulated and measured results validates the proposed design model. Additionally, the high in-band isolation of over 40 dB is demonstrated between all adjacent bands, highlighting the potential applicability of this technology in multiband scenarios.

Highly-miniaturized microfluidically-based frequency reconfigurable antenna diplexer employing half-mode SIRW

This article introduces a super-miniaturized frequency reconfigurable antenna diplexer based on microfluidic techniques. The proposed structure is developed using a half-mode substrate-integrated rectangular waveguide (HMSIRW). The antenna architecture consists of two HMSIRW cavities loaded with L-shaped slots, which are excited by two microstrip feedlines to realize two distinct radiating frequency bands. The footprint of the antenna diplexer is miniaturized by using the half-mode cavities. Further size reduction is achieved by the capacitive loading of the slots. The design evaluation, radiation mechanism, parametric analysis, and equivalent circuit model are discussed in detail. The empty fluidic vias are drilled on the bottom plane of the cavities and poured with various dielectric liquids to obtain independent frequency reconfigurability at two operating bands. For validation, a frequency reconfigurable antenna diplexer is designed, manufactured, and demonstrated experimentally. The measured results show that the return loss, isolation, and realized gains are greater than −20 dB, 28 dB, and 3.3 dBi, respectively, while ensuring small footprint of only 0.071λg2. The fabricated diplexer exhibits a frequency reconfiguration range greater than 17 % at both frequency bands.

A High Gain Circularly Polarized Slot Antenna Array for 5G Millimeter-Wave Applications

An air-filled substrate-integrated waveguide (AF-SIW) circularly polarized (CP) 1 × 8 mm wave antenna array is presented for fifth-generation (5G) applications. The presented slot antenna array consists of three layers of PCB and one layer of aluminum, which serve as the AF-SIW feeding network and the metal cavity radiation element, respectively. The CP characteristic is achieved by the use of an S-shaped aluminum radiation cavity on the top of the AF-SIW feeding network. The air-filled substrate-integrated waveguide technique is unitized to achieve high radiation efficiency. A wide input impedance bandwidth of 18.4% is obtained for the proposed antenna scheme, ranging from 34.5 GHz to 41.5 GHz, with a peak gain of 18 dBic. As for CP characteristic, the proposed antenna possesses a wide 3 dB axial ratio (AR) bandwidth, which is 16.4% (36.5 GHz to 43 GHz). The antenna scheme is fabricated and measured to verify the potential application as well as the promising performance. The measured results of the 1 × 8 antenna array shows that the wide AR as well as the input impedance are simultaneously achieved, which coincide well with the simulated results. Also, the measured results indicate that the proposed antenna scheme might be a good candidate for future mobile applications.

Four‐port dual CP MIMO antenna with enhanced isolation for 5G applications

SummaryIn this paper, a 4 × 4 MIMO (multiple‐input multiple‐output) antenna with metasurface (MS), which is composed of dual circularly polarized (CP) patch antennas, is proposed for 5G (sub‐6 GHz) applications. The MIMO antenna consists of four microstrip patch antennas. In order to improve the isolation of the MIMO antenna, parasitic elements are placed on the MS and layer of patch antennas. In addition, a substrate‐integrated waveguide (SIW) structure is used at the center of the MIMO antenna for this purpose. The proposed MIMO antenna is fabricated for validation tests. The antenna has overall dimensions of 115 mm × 115 mm × 3.2 mm (1.219 × 1.219 × 0.033 , where is the free space wavelength at the lowest operating frequency in 10‐dB impedance bandwidth). The MIMO antenna has 10‐dB impedance bandwidth (IBW) from 3.3 to 3.8 GHz (14.08%), 3‐dB axial ratio bandwidth (ARBW) from 3.42 to 3.69 GHz (7.59%), and 6.36‐dBi peak gain. The isolation is greater than 28.14 dB in the n78 frequency band (3.3–3.8 GHz).