Substrate Integrated Waveguide Coupler Research Articles

Cascaded Deep Q-Network for Optimization of Substrate Integrated Waveguide Couplers

In this brief, a method to automatically optimize substrate integrated waveguide (SIW) couplers with different power-dividing ratios is proposed. In the proposed method, a cascade model is presented for the first time. In this cascade model, four-port SIW network is classified into two typical elements: coupling and phase difference. By cascading these typical elements in a certain order, SIW coupler with different power-dividing ratios can be achieved. The order of the basic elements can be automatically decided by using deep Q-network (DQN). A library is built to store the optimization results. From the library, SIW couplers with different power-dividing ratios can be obtained in seconds. To validate the proposed method, multiple four-port directional couplers with different power-dividing ratios are designed. Three directional couplers are fabricated and experimentally verified. Furthermore, this method is also promising for the design and optimization of other circuits.

Liquid-Crystal Reconfigurable Coupler for Millimeter-Wave Applications

A Substrate-integrated waveguide (SIW) coupler whose coupling ratio is controllable at millimeter-wave frequency is presented. To realize this unique property, the SIW coupler is loaded with a tunable liquid crystal (LC) in the central region. To increase, translate and shift the tuning range of the LC to the required permittivity, an artificial dielectric slab is introduced and validated. A new approach to locally increase the permittivity of the LC is presented, wherein the relative permittivity is increased over the desired band. Initially, the variation in the relative permittivity of the LC is 2.46 to 3.5; the slab offers an increment in the variation, from 8.82 to 14.7. Varying the permittivity of the slab in the central region enables coupling ratio control. Based on the investigation of the proposed model, the design requirements and physical parameters to achieve a wide range of reconfigurability are obtained at the millimeter-wave band. For experimental/demonstration purposes, two reconfigurable coupler prototypes with angles of 15°and 55°between the arms are fabricated and characterized. The results demonstrate a tunable operating frequency to a certain extend with a controllable coupling ratio between output ports from 0.5 to 15 dB. These results show very good agreement with the values determined via simulation.

Design of low profile wideband high power waveguide to substrate integrated waveguide coupler

AbstractThis paper presents a new wideband waveguide substrate integrated waveguide (SIW) coupler with maximum deviation of ±0.5 dB in a 7.5–12.25 GHz bandwidth (48% fractional bandwidth). Proposed coupler consists of the standard WR90 waveguide and single layer/double clad SIW printed circuit board (PCB) which is placed crosswise on the waveguide. Proposed three port coupler (isolated port was ended with match load) has a two coupling level (average of coupling in 8–12 GHz frequency range) of 43.2 and 58.3 dB, which is correspond with the hole diameter of 3.5 and 3 mm, respectively. The main contribution of this work is based on the hybrid techniques of SIW and RWG for coupler design in the high power microwave application. Validation of the simulation results with measurement one proves that the proposed X‐band waveguide to SIW coupler is a good candidate for use in high power industrial/commercial applications.

Design and analysis of multi‐layer SIW coupler to use in phased array antenna feed network

AbstractIn this paper, a directional coupler is designed using the substrate integrated waveguide (SIW) method. The SIW coupler consists of a double‐layer with transverse rectangular slots in the middle of two layers. The proposed coupler contains three ports. The placement of ports is considered based on the generalization of the power divider network. Each layer is printed on 0.508 mm Rogers RT/Duroid 5880 ( and ). The coupling level is basically controlled by the number and size of the slots. This coupling ratio changes from −5 dB to −13 dB. It is complicated to design a single‐layer feed network for a two‐dimensional phased array antenna. The designed SIW coupler can be easily generalized to the feed network for a 2D phased array antenna that consists of a large number of antenna and phase shifter elements. The SIW coupler is simulated using CST software. The results of the analyses, simulations and experiments indicate good performances of the designed coupler.

A six‐port network based on substrate integrated waveguide coupler with metal strips

In this study, a novel coupling structure based on half-mode substrate-integrated waveguide (HMSIW) is proposed with a small size and broad bandwidth. The HMSIW coupler is realised by connecting their equivalent magnetic walls with metal strips, which avoids exposing the semi-enclosed magnetic walls outside. Hence, it has greater anti-interference capability than the existing HMSIW couplers. The directional coupling principle is introduced by analysing the proposed single connecting strip coupler. In order to lower return loss and higher isolation, a 3 dB directional coupler working from 10.8 to 16.8 GHz is designed with two connecting strips. Finally, a six-port circuit is achieved by utilising this compact 3 dB directional coupler. Furthermore, a broadband HMSIW power divider is optimised to satisfy the performance of this six-port circuit. The proposed coupler with metal strips helps to increase bandwidth and reduce size, which makes it more applicable to demanding systems with complex requirements such as detecting and transceiver systems. The 3 dB coupler and six-port circuit are fabricated and measured. The measured results are in accordance with the simulated data.

Design and Fabrication of PTFE Substrate Integrated Waveguide Coupler by SR Direct Etching

Design and Fabrication of PTFE Substrate Integrated Waveguide Coupler by SR Direct Etching

A Compact Millimeter-Wave Planar Directional Coupled Crossover With a Wide Bandwidth

A compact planar directional coupled crossover with a wide fractional bandwidth is proposed in this letter, which is composed of overlapping planar 3-dB couplers based on the substrate integrated waveguide (SIW) and stripline techniques. In the proposed structure, the TE10 mode and TEM mode can be transmitted simultaneously without any interaction, which is helpful to design and integrate the SIW and stripline couplers for realizing a wideband directional coupled crossover with a compact footprint. A prototype with a center frequency of 26 GHz for 5G applications is designed and fabricated. The experimental results show that the measured crossover has high isolation among all ports and good directional coupling performance in orthogonal directions. The proposed crossover has a compact footprint and low loss, which can be a good candidate for developing the miniature feeding networks for multiple beam antennas.

Multi-Functional Six Ports SIW Microwave Component for X-band Applications

ABSTRACTA novel symmetric two layer six ports multi-functional microwave component was designed and presented in the present study. The proposed component consists of two 90-degree broadband double layer substrate integrated waveguide couplers and two T-shape power dividers. By exciting each port, the component could act as a −6 dB equal power divider, an unequal −3/−6 dB 90-degree coupler, as well as a −3 dB equal coupler. This component with mentioned conditions covers 23% frequency bandwidth with maximum magnitude and phase error of ±0.5 dB and ±0.6 degree in all bandwidths, respectively.

Minimized multi‐layer substrate integrated waveguide 3‐dB small aperture coupler

AbstractA multi‐layer 3‐dB substrate integrated waveguide coupler is presented in this article. As a promising technique, the multi‐layer substrate integrated waveguide has been widely used in microwave and millimeter circuits and systems for its decrease in size. This design combines the Bethe hole coupling theory with the SIW technology to reduce the height and integrate with other planar circuits. More importantly, the strong coupling (3‐dB) coupler presented in this article utilizes the higher frequency band of TE10 mode to get a relatively bigger radius of aperture and in turn reduce the number of coupling sections, which significantly decrease the size of the coupler. The simulated results are in good agreement with the measured data.

Variable propagation constant directional coupler

Variable propagation constant directional coupler is proposed and demonstrated. Compared with its conventional counterpart, the proposed coupler uses variable waveguide propagation constants as an extra degree of design freedom to achieve the required signal addition and cancellation. The operation principle is mathematically formulated and a step-by-step design methodology is presented. Two double-layer two-hole substrate integrated waveguide couplers: namely, one forward directional coupler and one backward directional coupler, are fabricated to validate the proposed concept. A coupling of −20 dB is achieved in both couplers and the maximum isolation of −47 and −52 dB are obtained by the forward and backward structures, respectively.

Circuit analysis and optimisation of SIW branch line coupler with improved modelling of small metallic post in FDTD

In this study an improved model of small metallic post has been used in finite-difference time-domain (FDTD) method. This model has the advantages of wide range stability for different values of post radius, good accuracy and easy formulation. By using this model accurate results have been obtained in FDTD with large mesh size and therefore memory and calculation time have been reduced. Moreover circuit model has been used for the analysis and optimisation of substrate-integrated waveguide (SIW) branch line coupler. In this model a circuit is decomposed into several two or multi ports sub-circuits. Next, the proposed FDTD model is used to determine the scattering parameters of the sub-circuits. With a proper connection of the scattering parameters of these sub-circuits, the scattering parameters of the overall structure have been determined. Based on the improved post model in FDTD and using the circuit model a branch line SIW coupler with wider bandwidth has been designed and fabricated.

Design of a Novel Structure SIW 90° Coupler

This paper focuses on the analysis of passive devices using a recent emerging technology named Substrate Integrated Waveguide (SIW). This technology has been used in the conception of planar compact components for the microwave and millimeter wave’s applications. Through using Ansoft HFSS and CST code a substrate integrated waveguide coupler has conceived and optimized in this study. The SIW 90° coupler design simulations show good performances with low return loss, high isolation better than -20 and -40 dB, respectively and broad operational bandwidth.

Improving the Performance of Antenna using Substrate Integrated Waveguide Coupler

A compact antenna with a coupler is laid down using Substrate Integrated Waveguide (SIW) technique, which operate at X-band of frequencies. The SIW coupler has a SIW section which includes inserted metallic post. These metallic post acts as an inductive-post. SIW innovation is the most talented contender for the achievement of millimetre wave (mm-wave) coordinated circuits. Supported on planar dielectric substrate with bottom and top metal layers implanted with coated metal holes, it offers a compact, low cost, less loss and flexibility. The SIW has dynamic as well as passive components emanating area on the similar substrate. SIW technology has some attractive advantages, such as compact size, low loss, easy construction, low weight, high integration and is suited for all microwave and millimetre-wave works. The utilization of SIW technology encourages us to trim down return loss when weighed against other printed advances. The manufacturing process can simply be finished by means of normal Printed Circuit Board (PCB) process, where this present procedure’s cost will be shortened when assessed with conventional waveguides. The SIW coupler more frequently utilized as a part of radar, point-to-point radio and satellite. Simulations results come about demonstrate the coupler’s execution having low insertion loss, low return loss, and expansive operational data transmission and enclose fine seclusion.

X-Band Multi-Hole Directional Coupler with Folded Substrate-Integrated Waveguide

Based on the theory of multi-hole waveguide directional couplers, an X-band multi-hole directional coupler with a folded substrate-integrated waveguide has been designed and fabricated. Simulation results show that the proposed coupler has isolation greater than 19 dB and a return loss better than 18.5 dB over a 50% fractional bandwidth at 10 GHz. The proposed folded substrate-integrated waveguide coupler has been fabricated, and measured data are almost consistent with simulation results. Isolation greater than 17 dB and return loss better than 13 dB are experimentally validated.

Broadband substrate‐integrated waveguide T‐junction with arbitrary power‐dividing ratio

A novel broadband substrate-integrated waveguide (SIW) T-junction with an arbitrary power-dividing ratio is proposed. Three inductive posts are designed to adopt flexibility for the equal output T-junction to obtain a wide impedance bandwidth. To realise the unequal power-dividing ratio over a wide bandwidth, the SIW coupler is integrated with corner structures and a novel T-junction structure is formed. Three T-junctions with different power division ratios (1:1, 1:4 and 1:8) at a centre frequency of 6 GHz are simulated, fabricated and measured. The measured bandwidths are 60, 53 and 63.3%, respectively.

Single-Layer Wideband Circularly Polarized Patch Antennas for Q-Band Applications

In this communication, dual-fed wideband circularly polarized (CP) patch antennas based on the single-layer printed circuit board (PCB) process and the substrate integrated waveguide (SIW) technology are proposed. Firstly, a patch antenna fed by an SIW coupler is developed to achieve a measured 3 dB axial-ratio (AR) bandwidth of 21% (from 38 GHz to 47 GHz). Then, by introducing second-order inductive windows, an improved CP patch antenna is developed. The measured results show that the 1 dB gain bandwidth is expanded from 3 GHz to 9 GHz while the overlapped bandwidth of AR and reflect coefficient is maintained. Finally, a 2 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\times$</tex> </formula> 2 CP array is developed with a dual-polarized patch array. By carefully selecting the resonant frequency of the patches, a wide gain bandwidth is achieved. Moreover, by compensating the major error that deteriorates the AR bandwidth with a specially-designed coupler, the measured 3 dB AR bandwidth reaches as wide as 22.8%. The measured peak gain is 12.35 dBi.

Design and Analysis of SIW Cavity Backed Dual-Band Antennas With a Dual-Mode Triangular-Ring Slot

Substrate integrated waveguide (SIW) cavity backed dual-band triangular-ring slot (TRS) antennas are proposed for planar integration. First, a low profile dual band 45 ° linearly polarized (LP) antenna is designed and analyzed. The dual-mode TRS is proposed and developed by simultaneously exciting the mode of the slot and the mode of the patch inside the slot. To minimize the antenna size, the lowest mode (TE110 mode) of the SIW cavity is adopted to excite the TRS. The -10 dB impedance bandwidth at the higher band is 5.9%, 58.3% wider than that of the conventional SIW cavity backed slot antenna. The interactions of the SIW cavity, the slot mode and the patch mode are analyzed with circuit models and verified by full wave simulations, which provides a new insight into the SIW cavity backed antennas. Then, by exciting a pair of the 45° LP antennas with an SIW coupler, a circularly polarized (CP) dual band antenna with a small frequency ratio of 1.26 is developed. The two antennas are fabricated and tested, and the measured and simulated results agree well.

Design of K-Band Substrate Integrated Waveguide Coupler, Circulator and Power Divider

Design of K-Band Substrate Integrated Waveguide Coupler, Circulator and Power Divider

Broadband Substrate Integrated Waveguide 4$\,\times\,$4 Nolen Matrix Based on Coupler Delay Compensation

A broadband Nolen matrix in substrate integrated waveguide (SIW) technology is proposed and studied in this paper. Being feeding networks, Nolen matrices usually introduce significant phase dispersion in their standard form, thus limiting effective bandwidth. In this work, broadband frequency operation is achieved with adequate coupler delay compensation, resulting in a more parallel matrix topology. Consequently, H-plane couplers with continuous aperture are preferred in the proposed design as opposed to the cross-couplers previously used in the serial configuration. The SIW couplers and phase shifters of a balanced amplitude 4×4 Nolen matrix are designed at 77 GHz for radar applications. The resulting matrix that combines these elementary building blocks is fabricated and measured, and measured characteristics are in good agreement with theoretical and simulated predictions. This first design achieves excellent results over a 11.7% frequency bandwidth centered at 77 GHz. This modified Nolen matrix combines advantages of standard Nolen and Butler matrices and may be used as a building block for generalized orthogonal matrices.

Design of a Bethe-hole directional coupler using substrate integrated waveguide technique

This article proposes the design of a Bethe-hole (BH) directional coupler using substrate integrated waveguide (SIW) technique. The design can readily be coupled with, for instance, an antenna and is therefore suitable for millimeter-wave communication systems. Good agreements have been achieved between simulated and experimental results for a 25-dB BH SIW coupler operating in the X-band. Directivity greater than 20-dB and a coupling of 24.7 dB were obtained. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26119