Substrate Integrated Waveguide Cavity Research Articles

Low-Loss Self-Packaged Ka-Band LTCC Filter Using Artificial Multimode SIW Resonator

In this brief, a low-loss self-packaged Ka-band LTCC filter is proposed based on an artificial multi-mode substrate integrated waveguide (SIW) resonator. Two ridges and two metal strips are tightly integrated in one SIW cavity to form the artificial quad-mode resonator. Due to the shielding of the SIW cavity, the resonator realizes a high Q factor, which contributes to an extremely low loss of the Ka-band filter. A fast design method for the bandpass filter based on an artificial multi-mode resonator is introduced. A simple approach to accurately extract all external Q factors for multiple resonant modes at the same time is also discussed. A pair of transmission zeros are generated to improve the filter skirt selectivity. For verification, a filter operating at 28 GHz is fabricated on the LTCC process. The measured result shows a low insertion loss of 0.8 dB, which is attracted in millimeter-wave applications.

Miniaturized Quad-Band Filter Design Using Substrate Integrated Coaxial Cavity

We propose a miniaturized quad-band filter (QBF), designed using substrate-integrated coaxial cavities (SICCs). The employed SICC structure consists of two vertically stacked substrates with a large circular patch embedded in between. The embedded patch is segmented unevenly into four pieces, which are shorted to the cavity's bottom wall through one or two blind vias. This SICC structure exhibits four independently controlled resonances with frequencies much lower than the frequency of its conventional SIW cavity counterpart, thus achieving size reduction. A sample quad-band filter is designed and fabricated for experimental measurement. Reasonably good agreement between measured and simulated data is observed.

High Selectivity, Dual-Mode Substrate Integrated Waveguide Cavity Bandpass Filter Loaded Using CCSRR

In this paper, a third-order, high selectivity Substrate Integrated Waveguide (SIW) bandpass filter (BPF) loaded with Circular Complementary Split-Ring Resonator (CCSRR) is proposed for C band applications. The SIW cavity BPF comprises two stepped resonators ([Formula: see text] and [Formula: see text]) and one CSRR ([Formula: see text]) engraved on the top metal plate. Initially, the cavity loaded with stepped resonators ([Formula: see text] and [Formula: see text]) alone does not make a good selectivity on the lower out of band. Hence, the CCSRR is introduced between the stepped resonators ([Formula: see text] and [Formula: see text]) to improve the filter’s selectivity and enhance the filter’s bandwidth. The introduction of CCSRR enhances the selectivity on the lower out-of-band at 5.5[Formula: see text]GHz, and the extra pole increases the bandwidth. The metamaterial behavior of CCSRR is validated by permittivity extraction. The 3[Formula: see text]dB bandwidth of the third-order SIW filter is 840 MHz with a center frequency of 6.18[Formula: see text]GHz. The designed filter uses RTDuroid 5880 substrate of [Formula: see text] = 2.2 with a size of 28.4 × 28.4 × 0.51[Formula: see text]mm3. The proposed filter measurement and simulated results agree with each other.

Eight-element self-isolated MIMO antenna based on wideband SIW rectangular ring slot antenna

In this paper, a wideband low-profile substrate integrated waveguide rectangular ring slot (SIW RRS) antenna is introduced. Wide bandwidth is achieved due to the excitation of half-TE110 cavity mode and TM100 patch mode within the cavity. The working principle of the SIW RRS antenna is explained using its field distributions, and parametric study is carried out to aid in the design procedure. Also, different SIW cavities are investigated to understand their influence on the bandwidth. Further, an eight-element MIMO antenna is designed based on the SIW RRS antenna utilizing its self-isolating property. Antenna prototypes are fabricated and tested to verify the simulated results. The antenna element has a bandwidth of 22.03% and a peak gain of 7.46 dBi, and the MIMO antenna has a bandwidth of 22.8%, a peak gain of about 8.7 dBi, and a minimum isolation of 22.17 dB. The proposed antenna is a promising candidate for MIMO applications due to its merits of wideband, high-gain, good isolation, and low-profile.

High performance antenna-on-chip inspired by SIW and metasurface technologies for THz band operation

In this paper, a high-performance antenna-on-chip (AoC) is implemented on gallium arsenide (GaAs) wafer based on the substrate integrated waveguide (SIW) and metasurface (MTS) technologies for terahertz band applications. The proposed antenna is constructed using five stacked layers comprising metal-GaAs-metal-GaAs-metal. The conductive electromagnetic radiators are implemented on the upper side of the top GaAs layer, which has a metallic ground-plane at its underside. The metallic feedline is implemented at the underside of the bottom GaAs layer. Dual wrench-shaped radiators are framed by metallic vias connected to the ground-plane to create SIW cavity. This technique mitigates the surface waves and the substrate losses, thereby improving the antenna’s radiation characteristics. The antenna is excited by a T-shaped feedline implemented on the underside of the bottom GaAs substrate layer. Electromagnetic (EM) energy from the feedline is coupled to the radiating elements through the circular and linear slots etched in the middle ground-plane layer. To mitigate the surface-wave interactions and the substrate losses in the bottom GaAs layer, the feedline is contained inside a SIW cavity. To enhance the antenna’s performance, the radiators are transformed into a metamaterial-inspired surface (i.e., metasurface), by engraving periodic arrangement of circular slots of sub-wavelength diameter and periodicity. Essentially, the slots act as resonant scatterers, which control the EM response of the surface. The antenna of dimensions of 400 × 400 × 8 μm3 is demonstrated to operate over a wide frequency range from 0.445 to 0.470 THz having a bandwidth of 25 GHz with an average return-loss of − 27 dB. The measured average gain and radiation efficiency are 4.6 dBi and 74%, respectively. These results make the proposed antenna suitable for AoC terahertz applications.

A Novel Design for Dual-Band Wearable Textile Eighth-Mode SIW Antennas

A novel wearable textile dual-band antenna configuration based on a substrate integrated waveguide (SIW) cavity is presented. The miniaturization of the antenna is achieved by exploiting the magnetic field symmetry of a square SIW cavity, reducing its size to 1/8 of the full square cavity with an eighth-mode SIW configuration. This solution is applied to the design of a wearable dual-band antenna for Long Range (LoRa) applications. The antenna operating frequency covers both the UHF LoRa bands, the European (863-870 MHz) and the North American (902-928 MHz). The proposed design provides a low-cost and compact antenna, which is easy to fabricate and ensures a very good isolation and robustness with respect to the human body proximity. The commercial software CST Studio Suite has been used for the antenna design and simulations. A prototype has been fabricated and the measured results are in good agreement with numerical simulations.

SELF-QUADPLEXING SLOT ANTENNA FOR S- AND C-BAND APPLICATIONS

This paper demonstrates a novel kind of cavity-backed self-quadplexing slot antenna for S- and C-band applications. The proposed antenna consists of four distinct U-shaped slots of different lengths and produces quad frequency bands for wireless communication systems. These slots are excited through separate and orthogonally placed 50 Ω micro-strip feed lines and generate four distinct operating bands at 3.2, 4.1, 5.8, and 7.2 GHz. Due to the perturbation of the different U-shaped slots over a substrate-integrated waveguide cavity with defined positions, the high intrinsic port isolation value is better than 30.5 dB. Thus, the proposed unique antenna structure combines the four independent operating bands with minimum mutual coupling and negligible interference among the input ports, showing the antenna's self-quadplexing feature. The proposed antenna also has frequency tunability with unidirectional radiation patterns and gains of 5.8, 5.4, 4.01, and 3.47 dBi at corresponding operated frequencies. The cross polarization is below 17.3 dB and the front-to-back ratio is higher than 21.5 dB at all operating quad bands. Good agreement was obtained between the simulated |S| parameter and equivalent circuit model results.

Low-Profile Single-Layer Half-Mode SIW Filtering Antenna With Shorted Parasitic Patch and Defected Ground Structure

A low-profile single-layer half-mode substrate integrated waveguide (HMSIW) filtering antenna with compact circuit size is presented in this brief. The antenna features simple structure and consists of a half-mode substrate integrated waveguide cavity (HMSIWC), a shorted parasitic patch, and a folded defected ground structure (DGS) etched into the metallized ground plane. The half-mode technology is employed to reduce the overall dimension in the design. The shorted parasitic patch and the HMSIWC, both operating at half-mode states, are coupled with each other to form a second-order filtering response. And also a radiation null at higher stopband is introduced owing to the effects of the cross coupling. Furtherly, by etching a folded DGS into the metallized ground plane, an additional resonance in the passband and a controllable radiation null at lower stopband are simultaneously generated to broaden the impedance bandwidth and improve the selectivity of lower stopband respectively. For verification, a prototype of the developed HMSIW filtering antenna is designed, fabricated, and measured. The measured and simulated results are in good agreement, showing a wide impedance bandwidth of 9.2% at center frequency of 2.84 GHz, a flat in-band gain response with two controllable radiation nulls at both edges of the operating band, and a maximum boresight realized gain of 5.75 dBi. The proposed HMSIW filtering antenna demonstrates good in-band and out-of-band performance even with a very low profile of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.015~\mathbf {\mathrm {\lambda }} _{0}$ </tex-math></inline-formula> .

High Selectivity SIW Cavity Bandpass Filter Loaded CSRR with Perturbing Vias for Sub-6 GHz Applications

High Selectivity SIW Cavity Bandpass Filter Loaded CSRR with Perturbing Vias for Sub-6 GHz Applications

Evanescent‐mode bandpass filter using D‐shaped slotlines for spurious harmonic suppression

AbstractA novel miniaturized evanescent‐mode substrate integrated waveguide (SIW) bandpass filter with D‐shaped slotlines for spurious harmonic suppression is proposed in this letter. Closed‐form equations for the proposed evanescent‐mode SIW cavity are summarized and two D‐shaped slotlines are etched together as a pair by the face‐to‐face style to obtain the designed lowpass feature, which could be utilized to improve the out‐of‐band spurious harmonic rejection level. To validate the feasibility of this method, a miniaturized evanescent‐mode SIW filter with D‐shaped slotlines is designed and measured. The measured results show that this filter operates at 1.05 GHz with 2.4 dB insertion loss and 3.8% bandwidth. The out‐of‐band spurious rejection is lower than 16 dB up to 11 times of the higher cutoff frequency of the passband. All test results are in good agreement with the simulation results.

Compact, Order Extensible and Wide-Stopband Bandpass Filter Based on SIW Cavity With Rectangular Ring Slot

This brief introduces novel architectures of bandpass filters (BPFs) using a substrate integrated waveguide (SIW) cavity with a rectangular ring slot (RRS) for compact size, extensible order, and broad stopband responses. Two bandpass filters, which demonstrate a second-and a fourth-order Chebyshev response, respectively, are realized by employing identical cavities with RRS, without increasing the physical size of the circuit. A rectangular ring slot is etched along the perimeter and a metallic via is allocated towards the bottom edge of the cavity to realize the resonances. The resonant frequencies of different modes are controlled by introducing one or three slots, which enable the realization of the second and fourth-order BPFs with wide stopbands, respectively. The working principles of the filters are illustrated by applying the eigen-mode analysis, field distribution, and the coupling matrix. Finally, a second-order BPF centered at 0.87 GHz, and a fourth-order BPF centered at 0.92 GHz are synthesized, fabricated, and experimentally validated. As compared to the earlier works, the proposed fourth-order BPF offers competitive performance with a low insertion-loss of 0.7 dB, compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.036\mathbf {\lambda } ^{2}$ </tex-math></inline-formula> , and a wide passband of 22.1%. Additionally, the second- and the fourth-order BPFs achieve wide upper stopband responses of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.86{f} _{0}$ </tex-math></inline-formula> at a level greater than 20dB and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.98{f} _{0}$ </tex-math></inline-formula> at a level greater than 30dB, respectively.

Dual Circularly Polarized Broadband Antenna Array for Millimeter-Wave Applications

A planar dual circularly polarized (CP) broadband array is proposed in this letter. The antenna consists of two semicircular patches and two suspended metal posts. According to the investigation of our previous work, the circularly polarized mode generated by combining the patches and the metal posts can achieve very wideband CP radiation. In order to achieve dual CP radiation with similar performance, a new antenna element is proposed with a centrally symmetrical configuration. The orthogonally crossed slot etched on the substrate-integrated waveguide cavity is used to excite the antenna element. A 4×4 array is designed, fabricated, and tested. Measured results show that a 3 dB AR bandwidth of 28.28% (26–34.6 GHz) and 30.61% (26–35.4GHz) is achieved for left-handed CP (LHCP) and right-handed CP (RHCP) radiation, respectively. The 3 dB gain bandwidth of 22.81% (26.4–33.2 GHz) and 24.50% (26–33.26 GHz) for these two polarizations is obtained. The proposed array demonstrates the feasibility of dual-polarized radiation. It features the advantage of wide bandwidth, easy integration, and low cost, which is very suitable for millimeter-Wave system applications.

Design of Dual-Band Frequency-Selective Surfaces With Independent Tunability

A design approach for dual-passband frequency-selective surface (FSS) with independent tunability is proposed and implemented. The principle of the proposed design approach is elaborated based on an equivalent circuit model, and it is demonstrated that the construction of FSS unit cell with two independently controlled transmission poles plays a decisive role. Referencing to the proposed approach, a varactor-based polarization-insensitive dual-passband FSS with independent tunability is demonstrated experimentally for the first time. In this prototype, a shunted substrate integrated waveguide cavity (SIWC) like structure is designed to realize electromagnetic isolation and serve as the dc ground for varactors to simplify the dc bias feed network. Simulated and measured results show that both passbands located in L-band and S-band can be tuned independently, and the transmission characteristic of the designed tunable FSS (TFSS) possesses good angle stability.

Multilayer packaging dual‐band balanced bandpass filter based on dual‐mode substrate integrated waveguide cavities with split‐type topology

A new design method of the dual-band balanced bandpass filter (BPF) using multilayer packaging dual-mode substrate integrated waveguide (SIW) cavities is proposed. Split-type coupling topology based on dual-mode resonators is developed for the design. Firstly, a single-band balanced filter with perturbed metal vias is designed. The TE201 mode and the TE202 mode perturbed by the metal vias can form a passband. Secondly, an additional metal vias perturbed SIW cavity with the same dual-mode is placed in the lower layer for the bandstop function. A dual-band balanced BPF with split-type coupling topology is successfully realised. Compared with the traditional cascaded single-mode form, the proposed dual-mode split-type design has more compact size and can be more easily extended to multi-passbands. To verify the proposed method, a dual-band balanced filter operating at 13.3 and 14.2 GHz is designed, fabricated and measured. The designed dual-band balanced filter has good filtering performance including differential mode passband transmission and common mode rejection. Measured results show good agreements with simulated ones.

Compact Low-Loss Half-Mode Substrate Integrated Waveguide Filter With Controllable Transmission Zeros

Two novel planar filters with controllable mixed electromagnetic couplings are developed in this brief for C band operation. They are implemented with the half mode substrate integrated waveguide (HMSIW) technology. Owing to the half mode SIW cavity, both of the filters exhibit a compact size. The size of filter I is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.53\,\,{\boldsymbol{\lambda }}_{\mathbf {0}} \times 0.30 {\boldsymbol{\lambda }}_{\mathbf {0}}$ </tex-math></inline-formula> , while the size of filter II is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.47\,\,{\boldsymbol{\lambda }}_{\mathbf {0}} \times 0.28 {\boldsymbol{\lambda }}_{\mathbf {0}}$ </tex-math></inline-formula> . ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\boldsymbol{\lambda }}_{\mathbf {0}}$ </tex-math></inline-formula> represents the wavelength in the free space at the center frequency). A wide passband response with a quasi-elliptic characteristic and good out-of-band rejection is realized due to the transmission zeros (TZs) introduced by the etched slot structures on the top metal layer. By modifying the dimensions of the structure, the strength of the electric and magnetic coupling can be independently controlled, and consequently the position of TZs is controllable to achieve desired stopband response with high selectivity. As a validation of the concept, one prototype is fabricated and tested. Excellent agreement is observed between the simulated and measured results.

Hybrid microstrip/SIW power divider with improved output isolation

An eight-way hybrid microstrip/substrate integrated waveguide (SIW) power divider with good output isolation performance is proposed in this paper. The circuit consists of microstrip/SIW transitions and a cross-shaped SIW cavity. The good isolation characteristics is obtained by adding the resistors between the microstrip lines and the isolation resistors on the radial slotlines. The equivalent circuit is given in this paper to analyse the proposed power divider. A prototype was fabricated and measured. The measurement results show that the insertion loss (IL) is about 1.5 dB from 9.1 GHz to 10.15 GHz, and the input return loss (RL) is higher than 20 dB. The isolation of adjacent ports on the same side, adjacent ports on the different side, and opposite ports are higher than 17.5, 19, and 15 dB, respectively. The error between measurement and simulation is acceptable.

A Compact Dual-Wideband Magnetoelectric Dipole Antenna for 5G Millimeter-Wave Applications

A compact dual-wideband millimeter-wave magnetoelectric (ME) dipole antenna based on dual-mode operation is proposed in this article. The ME dipole consists of two mirrored U-shaped patches, a substrate integrated waveguide (SIW) cavity with slotted top and two metallized vias connecting the patches to the slot. The two mirrored U-shaped patches work as an electric dipole (E-dipole), while the slot on the top of the SIW cavity and two metallized vias works as a magnetic dipole (M-dipole). In the lower frequency band, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.5\lambda $ </tex-math></inline-formula> modes of the E-dipole and the M-dipole are excited to form the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.5\lambda $ </tex-math></inline-formula> mode of the ME dipole. In the higher frequency band, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\lambda $ </tex-math></inline-formula> modes of the E-dipole and the M-dipole are excited to form the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\lambda $ </tex-math></inline-formula> mode of the ME dipole. In order to achieve compact structure and wide bandwidths, an SIW cavity is designed to feed the antenna. The proposed design shows that the measured impedance bandwidths (return loss larger than 10 dB) are 24–29.3 and 35.5–43.5 GHz at least with the achieved gain of 4.8–6.1 and 6.8–8.7 dBi, respectively. The designed antenna is suitable for 5G dual-band millimeter-wave applications.

Design of a Compact Indirect Slot-Fed Wideband Patch Array with an Air SIW Cavity for a High Directivity in Missile Seeker Applications

This research proposes a compact indirect slot-fed wideband patch array antenna for a missile seeker application. The proposed single antenna consists of three dielectric layers for a radiator, an air substrate-integrated waveguide (SIW) cavity, and an indirect feeding network. The rectangular patch is used as a radiator on the first substrate layer, and the air SIW cavity (ASIWC) is employed to obtain high directivity and low mutual coupling characteristics in the second substrate layer. In the third layer, an indirect feeding structure is used to achieve the wideband characteristics in the Ka-band. The single element is extended to a 4 × 1 linear array with fabrication, and the fabricated array characteristics are measured in a full anechoic chamber. The measured operating fractional frequency bandwidth is 9.2%, and the measured array gain is 11.7 dBi at the bore-sight direction (θ0 = 0∘).

Dual‐band shared‐aperture antenna with high aperture reuse ratio and high isolation

This work presents a dual-band (3.5/26 GHz) shared-aperture antenna with high aperture reuse ratio and high isolation. The proposed 26-GHz 4 × 4 substrate integrated waveguide (SIW) cavity-backed slot array antenna consists of four hybrid TE130–TE310-mode SIW cavities, which can simplify the design of feeding network. The radiating slots are unequally offset and inductance windows are added for good impedance matching. The entire structure of the 4 × 4 slot array antenna also functions as an equivalent TM10-mode patch antenna at 3.5 GHz. The resonant frequency of the patch is fine-tuned by inserting an air gap instead of enlarging the patch length, thus ensuring high aperture reuse ratio. To enhance channel isolation, the patch is designed with a bandpass filtering response centered at 3.5 GHz by introducing a stub-loaded resonator feeding structure. For demonstration, a prototype of the proposed dual-band antenna was fabricated and measured. The measured results show that the proposed antenna achieves excellent dual-band performance, and its aperture reuse ratio and channel isolation are as high as 87.5% and 62 dB, respectively.

A Dual-Band Dual-Polarized SIW Cavity-Backed Antenna-Duplexer for Off-body communication

A novel dual-band, dual-polarized antenna-duplexer scheme is intended to use for WLAN 802.11a and ISM band applications using Substrate Integrated Waveguide (SIW) Technology. The antenna consists of two planar SIW cavities of different dimensions where a smaller sized diamond-shaped cavity is inserted inside the larger rectangular cavity to share the common aperture area. The diamond-ring shaped slots are etched in each cavity for radiation. The larger diamond-ring slot is excited with a microstrip feedline to operate at 5.2 GHz while the smaller slot is excited with a coaxial probe to operate at 5.8 GHz. The antenna produces linear polarization at 5.2 GHz (5.1–5.3 GHz) due to the merging of TE110 and TE120 cavity modes while circular polarization around 5.8 GHz due to orthogonally excited TM100 and TM010 modes (5.68–5.95 GHz). The slots are excited in an orthogonal fashion to maintain a better decoupling between the ports (i.e. –23 dB). The performance of the antenna has been verified in free space as well as in the vicinity of the human body. The antenna offers the gain of 6.2 dBi /6.6 dBi in free space and 5.8 dBi / 6.4 dBi on-body at lower-/ higher frequency-bands, respectively. Also, the specific absorption rate (SAR) is obtained<0.245 W/Kg for 0.5 W input power averaged over 10 mW/g mass of the tissue. The proposed design is a low-profile, compact single-layered design, which is a suitable option for off-body communication.