Substrate Integrated Waveguide Technology Research Articles

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.

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.

SIW based in-phase Gysel equal power divider for X-band application

This article presents a novel approach to designing fixed-width Gysel equal power divider (PD) in Substrate integrated waveguide (SIW) technology. Since the width and impedance of SIW are functions of its cut-off frequency, therefore, conventional Gysel PD design equations become non-applicable in SIW technology. Keeping this constraint, dependency of SIW line widths on operating frequency, novel design equations for the equal Gysel PD are derived for the fixed width line. Based on the derived equations, a circuit model of Gysel PD is developed, and the results are presented at 10 GHz. A simulation analysis of the proposed PD in SIW technology is carried out to support the theoretical analysis. Further, a prototype of the device is fabricated, and measurements have been done. From the experimental results, the reflection coefficients of all the ports are better than 15 dB, and isolation is better than 25 dB for the entire frequency band 9.5 to 10.5 GHz. The insertion loss varies between 1.88 to 3.28 dB in the operating band.

A novel 4 × 4 butler matrix with continuously tunable phase covering 360° range and application for 1‐D and 2‐D beam scanning array

AbstractA novel 4 × 4 Butler Matrix (BM) with continuously tunable phase covering phase range from −180° to 180° is proposed using substrate integrated waveguide technology. The proposed BM consists of two H‐plane hybrid couplers, two E‐plane hybrid couplers and four 180° tunable phase shifters. With this simple configuration, the proposed BM can realise a continuously tunable progressive phase difference from −180° to 180° in a one‐dimensional (1‐D) or two‐dimensional (2‐D) form. For demonstration, the proposed BM has been fabricated to feed a 1 × 4 or 2 × 2 broadband microstrip antenna arrays. The fabricated prototype has a 16.7% fractional impendence bandwidth centred at 6 GHz. The measured pattern for the 1‐D array showed a continuous beam scanning range from −39° to 39° in H‐Plane, while the measured radiation patterns for the 2‐D array showed continuous beam range from −27° to 30° in elevation and 0°–180° in azimuth. The measurement results were in good agreement with the simulation results.

Differential Sensors in Substrate Integrated Waveguide Technology Loaded With Complementary Split-Ring Resonators for Liquid Characterization

Differential Sensors in Substrate Integrated Waveguide Technology Loaded With Complementary Split-Ring Resonators for Liquid Characterization

A SIW Based Leaky Wave Antenna for Aerospace Applications in X Band

In the rapidly advancing field of aerospace communication and radar systems, the demand for high performance antennas operating in the X-band frequency range has increased significantly. For high speed communication, precise navigation, and accurate detection the antenna in X band is required.  In this paper, the design and analysis of a substrate integrated waveguide (SIW)-based antenna for aerospace applications operating at a frequency of 10.5 GHz. The proposed antenna design integrates the benefits of SIW technology, such as low loss, compact size, and compatibility with planar fabrication techniques, making it suitable for space-constrained aerospace platforms. The antenna had gain of 9.34 dBi, s11 of design is -28.3 at 10.5 GHz. The radiation pattern is approximately omnidirectional.

Wideband and Highly Selective BandPass Filter Using Substrate Integrated Waveguide Technology for Ku-Band Applications

A new compact design of bandpass filter using substrate integrated waveguide (SIW) is proposed and analyzed in this paper. It offers good in-band return loss, low insertion loss, wide passband, and high stopband attenuation. The filtering response is achieved by loading a couple of inverted tuning fork-shaped defected ground structures (DGS) on the bottom of the SIW cavity. DGS is utilized to enhance the upper stopband performance. To validate, the filter is fabricated using Rogers RT/Duroid 5880 with 0.508 mm thickness and tested. The filter has a center frequency of 15.44 GHz with 19% fractional bandwidth (FBW). The return loss is more than 20 dB and the insertion loss is about 1.2 dB. It finds its application in Ku band satellite communication.

Simple and Easily Connectable Transition from Empty Substrate-Integrated Waveguide to a 3D Printed Rectangular Waveguide

3D printing is one of the most promising manufacturing methods in the most developed technological fields, including microwave hardware fabrication. On the other hand, the well-known manufacturing methods of planar substrate integrated circuits allow high-quality prototypes to be made at low cost and with mass production capabilities. The combination of both manufacturing methods, 2D or 2.5D (substrate integrated circuits) and 3D (3D printed structures), will allow us to take advantage of the main strengths of each technology and minimise disadvantages. In this article, for the first time, a transition structure between the Empty Substrate-Integrated Waveguide (ESIW) technology—a planar waveguide integrated on a printed circuit board—and a standard rectangular waveguide manufactured by 3D printing is proposed. This transition will make it possible to combine planar circuits with 3D structures, thus taking advantage of the benefits of both types of technologies. The fabricated prototype presents low losses (0.6 dB for the transmission coefficient and 15 dB for reflection coefficient), good electrical response (very flat), and simultaneously good mechanical stability and robustness to manufacturing and assembly errors. The proposed design for this transition piece is easily realisable for a wide range of affordable 3D printers. Repeatability is guaranteed and the proposed transition allows us to combine different SIC structures to 3D printed circuits. Hence, this transition will enable advancements in the fabrication of microwave devices, particularly with regard to satellite communications.

Textile Antenna Sensor in SIW Technology for Liquid Characterization.

This study showcases the creation of an innovative textile antenna sensor that utilizes a resonant cavity for the purpose of liquid characterization. The cavity is based on circular substrate integrated waveguide (SIW) technology. A hole is created in the middle of the structure where a pipe is used to inject the liquid under test. The pipe is covered by a metal sheath to enhance the electromagnetic field's penetration of the tube, thus increasing the device's sensitivity. The resonance frequency of the proposed system is altered when the liquid under test is inserted into the sensitive area of the structure. The sensing of the liquid is achieved by the measurement of its dielectric properties via the perturbation of the electric fields in the SIW configuration. The S11 measurement enables the extraction of the electromagnetic properties of the liquid injected into the pipe. Specifically, the dielectric constant of the liquid is determined by observing the resonance frequency shift relative to that of an air-filled pipe. The loss tangent of the liquid is extracted by comparing the variation in the quality factor with that of an air-filled pipe after eliminating the inherent losses of the structure. The proposed SIW antenna sensor demonstrates a high sensitivity of 0.7 GHz/Δεr corresponding to a dielectric constant range from 4 to 72. To the best of our knowledge, this article presents for the first time the ability of a fully textile SIW cavity antenna-based sensor to characterize the dielectric properties of a liquid under test and emphasizes its differentiating features compared to PCB-based designs. The unique attributes of the textile-based antenna stem from its flexibility, conformability, and compatibility with various liquids.

Compact SIW-Based Self-Quadruplexing Antenna for Microwave and Mm-Wave Communications

A compact self-quadruplexing antenna is presented, using substrate-integrated waveguide (SIW) technology and operating at 5.8, 7.4, 28, and 38 GHz. The design process is based on bisecting diagonally a square cavity into two triangles to obtain two HMSIW cavities. The right-upper corner of the structure is separated by slots to incorporate mm-wave frequencies. By utilizing five capacitive slots, independent frequency tuning in the operating frequency bands is achieved. To the best of our knowledge, this is the most compact quadruplexing antenna in the literature that operates at both mm-wave and microwave frequencies, and it has the best isolation between ports. The size of the antenna is 0.25 λg2 and the isolation between ports is less than -26 dB. A prototype of the antenna is fabricated and measured, showing a good agreement with the simulations, and therefore confirming the design approach.

Millimeter-Wave Ferrite Circulator Integrated on Gap Waveguide Technology

In this work, a simplified analysis with a low dielectric-filled <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ka$</tex-math> </inline-formula> -band Y-junction circulator is designed and fabricated for the first time based on substrate-integrated gap waveguide (SIGW) technology. A new design equation is tailored based on a low dielectric filling considering the effect of fringing fields around the ferrite disk. The proposed circulator covers a wide frequency range with a good return loss and isolation at the center frequency. The proposed circulator can be incorporated with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ka$</tex-math> </inline-formula> -band satellites and radars in the millimeter-wave range.

An E‐plane horn antenna fed with E‐plane Tee junction conceptualized by SIW technology

AbstractA novel E‐plane horn antenna fed with E‐plane Tee junction, conceptualized using the substrateintegrated waveguide (SIW) technology is introduced and investigated. Conventional SIW‐inspired horn designs are mostly limited to H‐plane sectoral horns, portraying confined radiation along the H‐plane while unconfined, fan‐beam‐shaped radiation along the principal E‐plane. Such radiation characteristics restrict its usage to designs requiring an electric field parallel to the structure and ultimately narrow confined radiation along the principal E‐plane of the embodiment. The proposed design provides a glue‐less solution to designing an E‐plane horn fed by an E‐plane Tee junction, both conceptualized by the SIW technology, having relative ease of fabrication on dual copper clad Printed Circuit Boards. Such a design operates from 17.15 to 18.8 GHz (~9.2% operating bandwidth) with a realized gain greater than 10.5 dBi, making it suitable for applications requiring light‐weighted high‐gain E‐plane sectoral horn antennas.

A Review Paper on Horn Antenna Using SIW Technology

Abstract: In this paper, we review, Micro-strip patch antenna and Substrate Integrated Waveguide Technology (SIW). Horn Antennas have become attractive due to their inherent feature of being one of the solutions to many requirements associated with high-frequency bands. This paper presents a comparative study of different horn antennas, their operating frequencies, associated parameters and applications in terms of frequency bands also using the SIW technique, the construction of planar horn antenna is studied at K band and X band frequencies.

Wideband SIW based slot antenna for RADAR applications

In this case, a substrate integrated waveguide technology is used in conjunction with a cavity-backed slot antenna. The modified slot antenna, in comparison to the dumbbell-shaped slot, not only adds numerous additional resonance spots, but it also enables the antenna to attain a better gain. In addition to this, the high-order resonant modes that are contained inside the sub cavity may be stimulated by the ground coplanar waveguide feeding structure if the high-order modes are brought into close proximity with one another. Based on the results of the test, it has been determined that the suggested antenna achieves an impedance bandwidth of 26.7% between 18.2 and 23.8 GHz and a peak gain of 9.5 dBi at 20.4 GHz. At each of the three frequencies that were tested, the cross-polarization levels of the antenna are around 40 dB. Antennas are recognised as being among the most important parts of any communication system. Because of this, antenna design is now one of the most active areas of study within the field of communication studies. In contrast, applications like as air traffic radar, satellite communications, and point-to-point terrestrial connection demand highly concentrated radiation patterns that also have a wideband and high gain. Because of this more focused radiation pattern, there will also be an increase in the communication range.

Inkjet-Printed Ferrite Substrate-Based Vialess Waveguide Phase Shifter

Magnetically controlled waveguide-based phase shifters are desirable for their high performance, but are bulky and heavy, thus cannot be easily integrated with printed circuit board (PCB) based circuits. To tackle this, substrate-integrated waveguide (SIW) technology has been utilized, which brings the waveguide to a standard PCB, but requires large numbers of vias as well as multiple cavities in the substrate for ferrite slab placement. This implementation technique involves complex fabrication and yields a relatively low figure of merit (FoM). To alleviate this, we present the first completely vialess ferrite substrate-based waveguide phase shifter realized through low-cost inkjet printing technique. All the four sides of a yttrium iron garnet (YIG) substrate have been metalized through inkjet printing, allowing the fabrication of a conventional rectangular waveguide on a standard magnetic substrate. The prototype has been tested in symmetric as well as antisymmetric modes of biasing and peak FoMs of 160°/dB at 7.22 GHz and 332°/dB at 7.46 GHz have been measured, which are higher than those of the previously reported designs. This all-around inkjet printing approach can open the door to low-cost, integrable magnetic phase shifters with excellent RF performances.

Millimeter-Wave Monopulse Filtenna Array with Directive Dielectric Resonators

This paper presents a new millimeter-wave monopulse dielectric resonator (DR) filtering antenna (filtenna) array based on substrate-integrated waveguide (SIW) technology. The monopulse comparator realized by a square dual-mode (&lt;i&gt;TE&lt;/i&gt;&lt;sub&gt;102&lt;/sub&gt; and &lt;i&gt;TE&lt;/i&gt;&lt;sub&gt;201&lt;/sub&gt;) SIW feed cavity uses diagonal irises, of which couplings between the feed and next-stage cavities lead to almost identical filter responses for the sum and difference channels with compact size and a planar single-substrate structure. Both dielectric resonator antennas (DRAs) adopting &lt;i&gt;HEM&lt;/i&gt;&lt;sub&gt;133&lt;/sub&gt; mode for enhanced directivity are implemented with two filters based on SIW. The DR acts as the last resonator and the radiator in the filtenna. The prototype is designed at the Ka-band with a center frequency of 27.65 GHz and an operation bandwidth of 700 MHz. The measurement shows a 15-dB fractional bandwidth of 2.36%, a gain of 10.84 dBi for the sum channel, and a null depth of -15.6 dB for the difference channel.

Virtual antenna array for reduced energy per bit transmission at Sub-5 GHz mobile wireless communication systems

This paper presents an innovative technique to synthesize a virtual antenna array (VAA) that consumes less energy than conventional antenna arrays that are used in mobile communications systems. We have shown that for a specific spectral efficiency a wireless system using the proposed virtual antenna array consumes significantly less energy per bit (∼3 dB) than a wireless system using a conventional multiple-input multiple-output (MIMO) array. This means the adoption of the proposed VAA technology in smartphones, iPad, Tablets and even base-stations should significantly reduce the carbon footprint of wireless systems. The proposed VAA is realized by employing a pair of linear antenna arrays that are placed in an orthogonal configuration relative to each other. This orthogonal arrangement ensures the radiation is circularly polarized. The size of the standard radiating elements constituting the VAA were miniaturized using the topology optimization method. The design of the VAA incorporates substrate integrated waveguide (SIW) and metasurface technologies. The function of SIW in the design was twofold, namely, to reduce energy loss in the substrate on which the VAA is implemented, and secondly to mitigate unwanted electromagnetic interactions between the neighboring radiating elements and thereby enhancing isolation which otherwise would degrade the radiation characteristics of the array. Metasurface technology served to effectively increase the effective aperture of the array with no impact on the footprint of the array. The consequence of SIW and metasurface technologies was improvement in the gain and radiation efficiency of the array. The proposed four orthogonal 4-element VAA covers the entire sub-5 GHz frequency range, and it radiates bidirectional in the azimuth plane and omni-directional in the elevation plane. Moreover, it is relatively easy to design and fabricate. The proposed VAA has dimensions of 0.96λ0 × 0.96λ0 × 0.0016λ0 at mid-band frequency of 3 GHz. VAA has a measured gain of 25 dBi and radiates with 90% efficiency. The average isolation between the linear arrays constituting the virtual array is better than 27 dB.

A Dual-Polarized SIW Lens Antenna Array for Rx-/Tx-Integration at K/Ka-Band

The terminal antenna with dual-circular polarization reported here operates around 20 and 30 GHz, that is, in the down- and uplink frequency bands of current satellite communication systems. The passive array, this work focuses on, integrates the receive and the transmit (Rx/Tx) paths in a single aperture. This approach is shown to be advantageous compared to classical solutions with two separate antennas. The modules, the array consists of, are formed by a stack of eight linear subarrays that themselves are composed of an alternating series of four Tx-only and four combined Rx/Tx endfire antenna elements. The resulting brick architecture provides enough real estate for the future implementation of phased-array electronics. The array is implemented in substrate-integrated waveguide (SIW) technology. For improved matching, it is covered with a periodically shaped dielectric lens. A technique is proposed to mitigate cross-polarization in the pointing direction. A module is realized using standard technologies. The relevant array parameters are measured. The module patterns are synthesized from the individual element responses. They confirm the simulated results and, in particular, a bandwidth of more than 2.5 GHz for both Rx and Tx.

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 Planar SIW-Based Mm-Wave Frequency-Scanning Slot Antenna Array With No Scan Blindness at Normal

Planar antenna reflectors are the modern design trend of both multibeam and frequency-scanning antenna arrays. The planar implementation of reflectors is typically performed using substrate-integrated waveguide (SIW) technology. A reflector’s profile can be different from the canonical one (parabolic, elliptic, hyperbolic, etc.) because of the effect of spatial dispersion of the reflection coefficient of the SIW-based surface. It should be synthesized considering the magnitude and argument of the field reflected from such a surface to maximize the efficiency of the reflection. In this article, we present a planar millimeter-wave (mm-wave) slot antenna array with SIW-based horn–reflector feeding. We analytically formulate the optimization of the SIW surface dimensions while accounting for the spatial dispersion of the reflection coefficient. We minimize the dimensions of the planar horn–reflector feeding. Finally, we demonstrate that using a dual-slot radiating element, and we can avoid the effects of scan blindness along the normal direction. A prototype has been built and a good agreement has been achieved between the measured results and the predicted results based on calculations. The prototype achieved ±17° beam scanning within 16% of the operational frequency range, with no scan blindness along the normal direction.