Substrate Integrated Waveguide Feeding Research Articles

Wideband and High-Efficiency SIW Cavity-Backed Magneto-Electric Dipole Antenna Array

In this paper, a compact, wideband, and high-efficiency substrate integrated waveguide (SIW) feeding cavity-backed aperture-coupled magneto-electric (ME) dipole antenna element and its array are proposed. Firstly, an SIW cavity-backed and a modified bowtie dipole are designed for the antenna element which makes it possess a high gain and wide impedance bandwidth. The antenna element covers an impedance bandwidth of 66.3% from 10.7 to 21.3 GHz with a peak gain of 10.3 dBi. Secondly, a 4 × 4 array is designed using the proposed antenna element. And a full-corporate substrate integrated waveguide feeding network is introduced to excite the array elements for the antenna application with wide bandwidth and high efficiency. For validation, a prototype of 4 × 4 array is fabricated by standard printed circuit board (PCB) facilities and further measured. The measured −10 dB impedance bandwidth of the proposed 4 × 4 antenna array is 30% (12.75–17.25 GHz) with its gain being 18.2–20.9 dBi within the entire band. The measured maximum aperture efficiency of the antenna array is 94% at 14.92 GHz. Notably, the measured results agree well with simulations, and it shows great advantages over other similar antennas on efficiency and bandwidth.

Gain‐enhanced 60‐GHz SIW cavity‐backed slot array antenna using metallic grooves

AbstractIn this article, a 60‐GHz substrate integrated waveguide (SIW) cavity‐backed slot array antenna with metallic grooves is proposed. To feed the four slot antenna elements, an SIW feed structure with a microstrip‐to‐SIW transition is used. To account for the effect of an actual connector on the antenna performance, simulations including the V‐band connector model were carried out. The measured 10‐dB return loss bandwidth of the proposed antenna with the connector is 600 MHz (59.76‐60.36 GHz). Sixteen metallic grooves are used to enhance the gain characteristics. By adding grooves, the electric field is concentrated in the +z direction. The measured broadside gain of the proposed antenna array with grooves is 13.59 dBi. Compared to a conventional SIW cavity‐backed slot antenna array, the proposed antenna array with 16 grooves has an enhanced gain of 5.6 dB.

Reconfigurable Phased-Array Antenna Using Continuously Tunable Substrate Integrated Waveguide Phase Shifter

A low-cost $1 \times 4$ phased array incorporating continuously tunable substrate integrated waveguide (SIW) phase shifters is presented in this paper. Through seamless integration between antenna elements, phase shifters, and an SIW feeding network, the proposed phased array is assembled in a multilayered monolithic structure. To obtain a wide phase variation range, the electronically controllable phase shifter is constructed by introducing varactor diodes into a reflection-type architecture, which can also offer a simple solution to constitute the biasing circuit of the diodes. Due to the merits of adequate bandwidth and good radiation performance, an aperture-coupled patch antenna with multi-resonance characteristic is selected as the array element. Accordingly, a prototype of the proposed phased array was fabricated by applying standard printed circuit board (PCB) facilities. The measured results demonstrate that a continuous beam scanning range from −45° to 45° covering the whole operating band of 5.09–5.98 GHz is obtained. Meanwhile, a gain of up to 11 dBi and an impedance bandwidth of 16.1% are achieved. Owing to the features of continuous wide-angle steerable beam, easy fabrication, and integration, the proposed phased-array antenna is attractive for 5G Wi-Fi applications.

Wideband 2-D Monopulse Antenna Array With Higher-Order Mode Substrate Integrated Waveguide Feeding and 3-D Printed Packaging

A wideband 2-D monopulse antenna array with compact integrated structure is presented. First, based on the slotline/coplanar waveguide (CPW) excitation, a substrate integrated waveguide (SIW) higher-order mode excitation technique is discussed, and a wideband 1-D monopulse antenna array with miniaturized feeding structure is proposed. Then, the designed 1-D array is further extended into a 2-D array. The whole 2-D array is divided into four subarrays to simplify the array feeding. Orthogonal CPW-to-microstrip transition is introduced to utilize the array vertical space and obtain compact feeding arrangement. A 2-D monopulse comparator with broadband accurate feeding amplitudes and phases is also designed to feed the array. Finally, by implementing 3-D printing technology, the array components are packaged as a whole structure, and flexible array arrangement with high integration level can be realized. With the proposed design method, a 2-D monopulse array covering the entire $X$ -band (8–12 GHz, 40% bandwidth) is designed and fabricated. Compact structure and broadband monopulse performance make the proposed array an attractive candidate for wideband accurate target detecting and tracking applications.

Wideband High-Efficiency Circularly Polarized SIW-Fed S-Dipole Array for Millimeter-Wave Applications

A wideband high-efficiency millimeter-wave (mm-wave) circularly polarized (CP) array which is constituted by novel planar substrate integrated waveguide (SIW)-fed S-dipoles is presented in this communication. The proposed mm-wave CP S-dipole consists of two rotational symmetric curved arms and is fed differentially through aperture coupling, which features simple configuration and excellent performance. Detailed analysis is given to explain the operating principles of this element. It is noted that superior element performance including a wide impedance bandwidth of 43%, a wide 3 dB axial ratio (AR) bandwidth of 36%, and 1 dB gain bandwidth of 38% is achieved by the planar SIW-fed S-dipole. By feeding 64 in-phase S-dipole elements through a full-corporate SIW feeding network, a planar wideband highly efficient mm-wave $8 \times 8$ CP array is realized. To verify the design concept, a prototype operating at Ka-band is fabricated and measured. The measurement results indicate that the proposed array achieves a wide overlapped bandwidth of 27.6%, a high antenna gain of 25.2 dBic, and a high aperture efficiency of 89.9%. Attributed to the planar and robust array structure as well as its excellent performance, the presented array is a good candidate for various mm-wave applications.

An Endfire Circularly Polarized Complementary Antenna Array for 5G Applications

An endfire circularly polarized (CP) complementary antenna array is proposed for 5G applications. The proposed antenna is realized using a single-layered printed circuit board (PCB) with plated-through-hole technology and metal blocks. The antenna element consists of an open-ended substrate-integrated waveguide (SIW), an electric dipole, a double-sided parallel-strip line (DSPSL), and two metal blocks. It is simple in configuration and can achieve wide impedance and axial ratio (AR) bandwidths, stable gain and radiation patterns, and low back radiation. To increase the gain, a $1 \times 8$ antenna array is formed by integrating eight antenna elements with a planar 1–8 SIW feed network. The measurement results show that the proposed array can achieve an overlapping impedance and AR bandwidth of 23.8% from 56.3 to 71.5 GHz with an endfire left-handed CP (LHCP) gain from 14 to 15.3 dBic. The proposed array possesses all the salient features of the complementary source in symmetric and stable radiation patterns, low back radiation, and wide bandwidth.

Triple‐mode bandpass filter

triple‐mode bandpass filter

Design and Implementation of SIW Cavity-Backed Dual-Polarization Antenna Array With Dual High-Order Modes

In this communication, a novel approach for high-order modes excitation using substrate-integrated waveguide (SIW) is proposed for the implementation of a dual-polarization cavity-backed slot antenna. The antenna consists of a resonant SIW cavity with eight radiating slots and two separated SIW feeding networks. The vertically linear polarization (VLP) and horizontally linear polarization (HLP) are realized by adopting the TE430 and TE340 modes with different signal schemes. The field distributions and the surface currents of the TE430 and TE340 modes are used to analyze and illuminate the radiation mechanism. To further validate the proposed design, a $2 \times 2$ polarization-diverse SIW cavity-backed antenna array is fabricated and tested. The measured results show that the impedance bandwidths (S11 < −10 dB) for the two linear-polarization (LP) states are 10.73–10.9 GHz and 10.75–10.83 GHz, respectively, while the 3 dB axial ratio bandwidth for the right-hand circular polarization (RHCP) is 10.75–10.83 GHz. The measured peak gains of the two LP modes and CP mode are 13.4, 12.92, and 12.2 dBi, respectively. The proposed approach demonstrates an effective way of high-order modes (TE430 and TE340 modes) generation in a single SIW cavity, which has significant meaning in polarization-diversity applications.

Broadband and High-Gain SIW-Fed Slot Array for Millimeter-Wave Applications

A broadband and high-gain substrate integrated waveguide (SIW)-fed slot antenna array is demonstrated at $Q$ -band. Aperture coupling is used for interconnecting the two adjacent substrate layers. It is proposed to improve the impedance matching and the gain of the antenna element simultaneously by stacking a metallic cross-shaped radiating slot atop a cross-shaped coupling slot. For proof of concept, a $4\times 4$ antenna array with a low-loss SIW feeding network is further designed and measured. The measured impedance bandwidth of the proposed $4\times 4$ antenna array is 20.5% from 42.4 to 52.1 GHz for $|S_{11}|\leq -10$ dB. The measured peak gain is 19.4 dBi at 50 GHz. The measured and simulated results are in good agreement.

Planar Array Topologies for 5G Communications in Ku Band [Wireless Corner

Several low-cost feeding network configurations have been tested for an antenna array eligible for a 5G communication environment. Microstrip and substrate integrated waveguide (SIW) technologies have been evaluated in the feeding network and compared in terms of dielectric loss and directivity performance. Although microstrip dielectric loss is lower, a higher gain value is obtained with an SIW feeding network due to the directivity maximization. Three gain values have been implemented with different array sizes of 4 × 4, 8 × 8, and 16 × 16 radiating elements with a two-level corporate feeding network (CFN) in SIW and microstrip technologies. Measured matching bandwidth under -10 dB more than 20%, whereas the -1-dB gain bandwidth is 6%.

Compact low-cost substrate integrated waveguide fed antenna for 122 GHz radar applications

AbstractThis paper describes the design and characterization of a compact substrate integrated waveguide (SIW) fed antenna for the 122 GHz industrial, scientific, and medical band. The use of a single RO4350B substrate layer and the SIW feeding ensure a low-cost fabrication. Two versions of the antenna are presented differing in antenna gain and size. For measurement purpose, a transition from rectangular waveguide to SIW is introduced. Measurements of the radiation pattern have been performed and show good agreement with the numerical results for both antennas and an antenna gain up to 7.14 dBi.

Wideband, Low-Profile Patch Array Antenna With Corporate Stacked Microstrip and Substrate Integrated Waveguide Feeding Structure

In this communication, a corporate stacked microstrip and substrate integrated waveguide (SIW) feeding structure is reported to be used to broaden the impedance bandwidth of a 4 × 4 patch array antenna. The proposed array antenna is based on a multilayer printed circuit board structure containing two dielectric substrates and four copper cladding layers. The radiating elements, which consist of slim rectangular patches with surrounding U-shaped parasitic patches, are located on the top layer. Every four radiation elements are grouped together as a 2 × 2 subarray and fed by a microstrip power divider on the next copper layer through metalized blind vias. Four such subarrays are corporate-fed by an SIW feeding network underneath. The design process and analysis of the array antenna are discussed. A prototype of the proposed array antenna is fabricated and measured, showing a good agreement between the simulation and measurement, thus validating the correctness of the design. The measured results indicate that the proposed array antenna exhibits a wide |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB bandwidth of 17.7%, i.e., 25.3-30.2 GHz, a peak gain of 16.4 dBi, a high radiation efficiency above 80%, and a good orthogonal polarization discrimination of higher than 30 dB. In addition, the use of low-profile substrate in the SIW feeding network makes this array antenna easier to be integrated directly with millimeter-wave frontend integrated circuits. The demonstrated array antenna can be a good candidate for various Ka-band wireless applications, such as 5G, satellite communications and so on.

Air-Filled Substrate Integrated Waveguide Fed Magneto-Electric Dipole Antenna Array for Millimeter-Wave Applications

A substrate integrated magneto-electric (ME) dipole antenna array with an improved radiation efficiency is presented in the 28-GHz band. A novel full-corporate air-filled substrate integrated waveguide (SIW) feed network with low losses is designed and realized by utilizing the low-cost printed circuit board (PCB) facilities. Different from most previous millimeter-wave planar arrays consisting of 2 × 2 subarrays, an SIW fed sub-array with a larger size of 2 × 4 is investigated to simplify the configuration of the major portion of the array feed network, which is of importance to the successful realization of the air-filled SIW feed network. An 8×8 array prototype with a four-layered geometry is fabricated and measured to verify the design. The array has an impedance bandwidth of 25.9%, a gain up to 26 dBi and stable radiation patterns over the operating band. Benefitted from the absence of the significant dielectric loss in the feed network, a high antenna efficiency of 80% is also achieved. The proposed design provides an effective method to improve the achievable gain and efficiency characteristics of the substrate integrated arrays with a large size that are attractive for millimeter-wave wireless applications.

Broadband Coaxial Rotary Joint With Simple Substrate Integrated Waveguide Feeder

This paper presents a broadband coaxial rotary joint with simple single-layer substrate integrated waveguide (SIW) feeder. The annular slot etched on the surface of SIW can effectively convert TE10 mode in the rectangle SIW into the rotational symmetric TEM mode in the coaxial line. Broadband impedance matching can be achieved because the additional capacitive coupling between the short-circuited circular metallic patch and coaxial line. Comparing with previous SIW fed rotary joints, the proposed design has the advantages of wider bandwidth and simpler feeding structure. The equivalent circuit is given to explain the design. A prototype centered at 12 GHz is fabricated with the 10-dB impedance matching bandwidth of 24.9% and the minimum insertion loss of 0.3 dB.

New Design of Beam-Formed Leaky-Wave Antenna Based on Substrate Integrated Waveguide in a Confined Space

A novel design of leaky-wave antenna (LWA) with beam-formed radiation pattern based on substrate integrated waveguide (SIW) is proposed in this communication. The design is based on the idea of superposing radiations from the $n = -1$ space harmonic of different periodic structures in a weighting way. The effect of structural parameters on the radiation performance is first studied using Fourier transform. Then, different periodic structures are mapped into a final composite structure to realize the desired radiation pattern, which is set to be a secant distribution according to the features of long straight confined space considered in this communication. Moreover, a novel double-layer SIW feeding network is proposed and used to construct an LWA array to improve the efficiency and gain. Simulated results are compared with experimental results to validate the proposed idea and design.

Generalized Multimode SIW Cavity-Based Sensor for Retrieval of Complex Permittivity of Materials

In this paper, the generalized substrate integrated waveguide (SIW) cavity technique is presented for the retrieval of broadband complex permittivity of medium loss dielectrics using a number of higher order modes of the proposed cavity. The proposed SIW cavity design improves the coupling by implementing a novel feeding topology to achieve a better quality factor for the higher order TE $_{10n}$ modes as compared with the conventional SIW feeding arrangement. The conventional SIW cavity perturbation formula is modified to overcome various limitations of the SIW topology, such as the lower $Q$ -factor, lower sample to cavity volume ratio, and larger frequency shifts observed for the higher order modes. The applicability of the proposed technique is first numerically validated using independent data obtained with the help of full-wave electromagnetic solver, and then, the accuracy is compared with various cavity-based techniques available in the literature. Finally, the proposed SIW cavity sensor is fabricated on Rogers’ RT5880 substrate, where a number of standard RF substrates are tested using the network analyzer. The proposed generalized scheme based on the improved SIW cavity provides reasonably accurate values of the complex permittivity of the medium-loss dielectric substrates at multiband of microwave frequency in the range of 10–20 GHz.

Millimetre‐wave high‐gain circularly polarised SIW end‐fire bow‐tie antenna by utilising semi‐planar helix unit cell

In this work, a high-gain circularly polarised (CP) substrate integrated waveguide (SIW) bow-tie antenna is presented. The proposed antenna includes a pair of bow-tie radiators. To centralisation radiated pattern and recede side lobe and back lobe level two tilted rows of metalised via hole at the end of the SIW feed line is used. The methods of increasing the antenna gain and generating the CP are discussed. The proposed antenna was fabricated to validate simulated results. The designed structure operates across 40-68 GHz and exhibits a gain of 10-12.5 dBic. In addition, the proposed antenna exhibits a 3-dB axial ratio bandwidth from 54 to 64.3 GHz.

Broadband and High-Gain SIW-Fed Antenna Array for 5G Applications

A broadband and high-gain substrate integrated waveguide (SIW)-fed antenna array is demonstrated for 5G applications. Aperture coupling is adopted as the interconnecting method in the two-layer SIW feeding network. Two pairs of metallic posts act as dipoles and are surrounded by an air-filled cavity. The height of the cavity is designed to be higher than that of the posts to broaden the bandwidth. The measured impedance bandwidth of the proposed $8{\times} 8$ antenna array is 16.3% from 35.4 to 41.7 GHz for $|S_{11}|\leqslant -10$ dB, and the measured peak gain is 26.7 dBi at 40 GHz. The measured radiation efficiency of the antenna array is 83.2% at 40 GHz. The proposed antenna array which is suitable for 5G applications at 37 and 39 GHz bands shows stable radiation patterns, high gain, and broad bandwidth.

High Gain, Broadband and Dual-Polarized Substrate Integrated Waveguide Cavity-Backed Slot Antenna Array for 60 GHz Band

In this paper, a compact substrate-integrated waveguide (SIW) cavity-backed slot antenna array with high gain, broadband, and dual-polarization performances is proposed for 60-GHz applications. An enhanced 17.1% impedance bandwidth was achieved by cutting semi-circle edges on the conventional slot radiator. A simplified SIW feed network is aperture-coupled vertically and constructed on a double-layered structure to implement the dual-polarization operation. By adopting innovative techniques on both radiating element and double-layered SIW feed networks, a high-gain, broadband, and dual-polarized $8\times8$ antenna array was designed on three-layered printed circuit board that allows for mass production. This configuration also resolves the trade-off between the bandwidth and gain of the existing 60-GHz dual-polarized antenna array. Its feasibility is proved by obtaining a measured gain in the range of 19.7–22.3 dB and an enhanced impedance bandwidth of 17.1% over 55.7–66.1 GHz for both horizontal and vertical polarizations. With advantages of high-gain, broadband, and dual-polarization performances in a low-cost low-profile structure, the proposed antenna array is a promising candidate for millimeter-wave wireless systems.

Millimeter-Wave Planar Broadband Circularly Polarized Antenna Array Using Stacked Curl Elements

Using aperture-fed stacked curl elements, a full corporate-fed millimeter-wave planar broadband circularly polarized antenna array is proposed. First, the stacked curl element is aperture-fed, using the substrate-integrated waveguide (SIW) feeding network. This element is designed under a specific boundary condition, which leads to an excellent agreement of impedance bandwidth and axial ratio (AR) bandwidth between the designed element and the corresponding antenna array. Simulation results show that the antenna element achieves 35.8% impedance bandwidth and 37.8% 3 dB AR bandwidth with a maximum gain of 8.2 dBic. Then, a $2\times 2$ subarray is designed to achieve 33.1% impedance bandwidth. Next, the full-corporate SIW feeding scheme is utilized to construct the $8\times 8$ broadband antenna array. Finally, the $8\times 8$ antenna array is fabricated and its performance is evaluated. Measurement results show that its impedance bandwidth is 35.4%, 3 dB AR bandwidth is 33.8%, and 3 dB gain bandwidth is 32.2% with a peak gain of 23.5 dBic. Considering these three types of bandwidth together, its overall bandwidth is 30.6%. Good efficiency of about 70% is obtained because of the low-loss full-corporate SIW feeding scheme. A $4\times 4$ multibeam array is also simulated to verify the multibeam potential of the proposed antenna array.