Substrate Integrated Waveguide Feeding Network Research Articles

Design of an Air-Filled Slot Antenna and Array for Millimeter-Wave Applications

This communication introduces a new structure of wideband slot antenna with high gain and stable radiation patterns for millimeter-wave (mmW) applications. It is the first attempt to apply an air-filled I-shape slot excited by a substrate-integrated-waveguide (SIW) feed. The slot can achieve lower <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> -factor contributing to a wider bandwidth. In addition, the feature of even electric field distributions across the operating bandwidth produces very stable gain performance for the proposed antenna. The proposed antenna is realized using a single-layered PCB substrate with plated-through-hole technology, which is cost effective and easy to fabricate. In addition, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times8$ </tex-math></inline-formula> antenna array based on the proposed antenna element is developed with a planar 1–8 SIW feeding network. The measurement results show that the proposed array can achieve an impedance bandwidth of 36.6% from 58 to 84 GHz with a peak gain of 16 dBi. These performances ensure that the proposed antenna array is a promising candidate for mmW communications.

Developing Broadband Microstrip Patch Antennas Fed by SIW Feeding Network for Spatially Low Cross-Polarization Situation.

A stacked multi-layer substrate integrated waveguide (SIW) microstrip patch antenna with broadband operating bandwidth and low cross-polarization radiation is provided. A complete study on the propagating element bandwidth and cross polarization level is presented to demonstrate the importance of the design. The proposed antenna includes three stacked printed circuit board (PCB) layers, including one layer for the radiating 2 × 2 rectangular patch elements and two SIW PCB layers for the feeding network. There are two common methods for excitation in cavity-backed patch antennas: probe feeding (PF) and aperture coupling (AC). PF can be used to increase the bandwidth of the antenna. Although this method increases the antenna’s bandwidth, it produces a strong cross-polarized field. The AC method can be used to suppress cross-polarized fields in microstrip patch antennas. As microstrip patch antennas are inherently narrowband, the AC method has little effect on their bandwidth. This paper proposes an antenna that is simultaneously fed by AC and PF. As a result of this innovation, the operating bandwidth of the antenna has increased, and cross-polarization has been reduced. Actually, the combination of probe feeding and aperture coupling schemes leads to achieving a broadband operating bandwidth. The arrangement of radiator elements and cavities implements a mirrored excitation technique while maintaining a low cross-polarization level. In both numerical and experimental solutions, a less than −30 dB cross-polarization level has been achieved for all of the main directions. A fractional impedance bandwidth of 29.8% (10.55–14.25 GHz) for < −10-dB is measured for the proposed array. Simulated and measured results illustrate good agreement. Having features like low cost, light weight, compactness, broadband, integration capabilities, and low cross-polarization level makes the designed antenna suitable for remote-sensing and satellite applications.

A 60 GHz Rhombic Patch Array Antenna With High Gain, Low Sidelobe Level, and Reduced Array Area

This work designs a 60 GHz rhombic patch array antenna with high gain, low sidelobe level (SLL), and reduced array area. This antenna consists of eight linear serial arrays with varying number of patches. A slot-coupled center-fed structure of substrate-integrated waveguide (SIW) is designed to simplify the complex feed network required for direct excitation of planar arrays and reduce insertion loss. The rhombic configuration utilizes the quantity ratio of patches for equivalent taper excitation to reduce SLL, rather than the use of tapered width as in traditional designs, which can achieve high gain and avoid cumbersome resizing of patches and connecting lines. An array factor analysis method is proposed to predict the SLL of the antenna. To form a planar array and further reduce the H-plane SLL, a -25-dB Dolph-Chebyshev SIW feed network is constructed. The measured gain of the rhombic array antenna is 18.2 dBi, and the E-plane and H-plane SLLs are less than -20 dB and -25 dB, respectively. This work also simulates a reference uniformly excited high-gain 8&#x00D7;10 array antenna. Compared to this reference antenna, the proposed rhombic array antenna has similar simulated gain but much lower SLL and 23% smaller array area.

Broadband and efficient patch array antenna fed by substrate integrated waveguide feed network for Ku‐band satellite applications

A new class of multi-layer microstrip patch antenna (MPA) array fed by substrate integrated waveguide (SIW) cavities is presented for Ku-band applications. An efficient compact multi-layer SIW feeding network is designed, which has lower losses than the conventional corporate feeding network based on microstrip lines or coplanar waveguides. A 4 × 4 array consists of four stacked layers, including three based on the SIW technology as a feeding network and one layer for the radiating antenna array. Each layer can easily be fabricated from a dielectric substrate and processed using the printed circuit board (PCB) technology. Afterward, all the PCB laminates are stacked together and tied by screws. The measured antenna operates from 11.2 to 13.6 GHz achieving 19.35% bandwidth. The measured peak gain at 12.5 GHz is 17.1 dBi, equivalent to 71.47% aperture efficiency. The fabricated array exhibits several advantages: broadband, low cost, compactness, high radiation efficiency, high aperture efficiency, and lightweight, which makes it a candidate for Ku-band satellite applications.

Efficient Transition Hybrid Two-Layer Feed Network: Polarization Diversity in a Satellite Transceiver Array Antenna

In this article, an efficient solution for the development of a new class of two-layer microstrip patch antenna (MPA) with orthogonal polarization ports, based on substrate-integrated waveguide (SIW) through an aperture coupling technique, is presented. Applying the SIW feeding network and aperture coupling to feed the MPA reduces the losses resulting from the feeding circuit and gives a more compact and efficient system. The proposed 4 × 4 array consists of two stacked layers, including an SIW layer as a feeding network and one layer as an antenna layer. The main design feature is the dual orthogonal port to generate different linear polarizations (LPs) (horizontal, vertical, 45°, and 135°). Each layer can be easily fabricated by a single layered printed circuit board (PCB) technology, and then PCB laminates are fixed together using screws. The measured -10-dB impedance bandwidth spans from 9.25 to 10.2 GHz (9.76%). The maximum measured gain at 9.9 GHz is 18.2 dB. The peak radiation efficiency is 84%. The proposed dual orthogonal port antenna exhibits low cost, ease of design, lightweight, high efficiency, and compactness, which makes it a suitable candidate for the polarization diversity in a transceiver for Earth-station applications.

A Low-Profile Vertically Polarized Magneto-Electric Monopole Antenna With a 60% Bandwidth for Millimeter-Wave Applications

A millimeter-wave (mmW) low-profile wideband magneto-electric (ME) monopole antenna with the vertically polarized endfire radiation is presented by combining a pair of the top-loaded electric monopoles with a thin open-ended substrate integrated waveguide (SIW) with the extended lower broad wall. The antenna has a profile of 0.19 wavelength at the center frequency of the operating band, a wide bandwidth of 60.7% (from 23.5 to 44 GHz) covering all the fifth-generation (5G) mmW bands in the Ka-band, a stable gain of around 7 dBi, and a tilted radiation pattern. Then a 1 × 8 ME-monopole array is designed to investigate the beam scanning properties and the effects of the metallic ground and the polycarbonate radome, which should be considered in practical applications. As a sample, a 1 × 8 array fed by an SIW feed network, assembled on a metallic ground plane, and covered by a polycarbonate radome is finally designed, fabricated, and measured. The prototype achieves promising radiation features with a gain up to 15.3 dBi. Owing to the compact low-profile structure with good performance, the proposed design would be valuable to the mmW applications.

A Compact Wideband Circularly Polarized Magneto-Electric Dipole Antenna Array for 5G Millimeter-Wave Application

A compact wideband circularly polarized (CP) magneto-electric (ME) dipole antenna array is proposed. In order to achieve compact size and wideband characteristics, a novel substrate integrated waveguide (SIW) to coaxial transition (SCT) was designed to connect the lightning-shaped ME-dipole antenna element and an SIW feeding network. Particularly, an SCT-based power divider network together with the sequential-rotation (SR) technique was employed to improve the axial ratio (AR) bandwidth of the $4\times 4$ antenna array. The antenna array prototype was fabricated to verify the design. Measured results show that an impedance bandwidth of 27.7% (23.3–30.8 GHz) and 3 dB gain bandwidth of 25.3% (23.5–30.3 GHz) were achieved. Moreover, a 3 dB AR bandwidth of 27.8% (23.2–30.8 GHz) with a peak gain of 20.2 dBic was also recorded. Therefore, it is a good candidate for the fifth-generation (5G) millimeter-wave (mm-wave) communications.

A compact and wideband array antenna with efficient hybrid feed network

This study presents a high-efficient, compact, and broadband microstrip patch antennas (MPAs) based on substrate-integrated waveguide (SIW) for X-band applications. The proposed array consists of three stacked layers from top to bottom, including one layer as the antenna layer and two SIW layers as a feeding network. The performance was focused on improving the impedance bandwidth and radiation efficiency by mitigating the loss from the feed network while also maintaining the compact design. To this end, the SIW feeding network was designed to feed the MPA to save the physical aperture size which resulted in a more compact and efficient radiating structure. The overall size of the proposed array is compact and extra surface area around the radiation aperture has not been occupied. The measured −10 dB impedance bandwidth span is from 8.9 to 10.9 GHz (20.2%). The maximum measured gain at 10.6 GHz is 10.6 dBi. The results show that the simulated radiation efficiency and the measured aperture efficiency are more than 75% and 50%, respectively. The fabricated array exhibits great advantages such as wide operating bandwidth, lightweight, low-cost, high aperture efficiency, high radiation efficiency, and compactness which make it a good candidate for X-band applications.

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.

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 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.

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%.

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.

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.

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.

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.

Polarization-Adjustable Planar Array Antenna With SIW-Fed High-Order-Mode Microstrip Patch

This communication presents a high-order-mode microstrip patch antenna driven by substrate integrated waveguide (SIW) for millimeter-wave polarization-adjustable applications. Different polarization status can be yielded from variable excited signals, including vertical and horizontal linear, right-handed and left-handed circular polarizations. In the patch antenna configuration, an enlarged aperture coming from high-order mode makes it easy to be fed by orthogonal SIWs for dual polarizations. Loaded slots on the patch significantly improve the radiation patterns. The impedance bandwidth with dual resonances is originated from the SIW slot and patch modes. A Ka-band $2\times 2$ antenna array integrated with single-layer SIW feeding network is designed and tested to illustrate this technique. The results manifest that the planar integrated $2 \times 2$ antenna array features adjustable polarization with considerable gain. Furthermore, a two-layer scheme of orthogonal SIW feeding is developed, which would provide a more flexible topology for the scale-expandable array antenna with adjustable polarizations.