Substrate Integrated Waveguide Cavity-backed Slot Antenna Research Articles

Multiple-input multiple-output dual-band dual-circularly polarised SIW cavity-backed slot antenna for satellite and 5G systems

ABSTRACT A dual-band 2 1 multiple-input-multiple-output (MIMO) antenna based on substrate integrated waveguide (SIW) cavity for both satellite (in K-band) and 5 G applications is proposed. Initially, the SIW cavity consisting of metallic vias on all four sides is implemented. For MIMO configuration, this cavity is divided into two smaller SIW cavities using a row of metallic vias and excited using the coaxial feed. By etching an asymmetric cross-slot (AXS) with tuned dimensions on top of the SIW cavity, a dualsense of circular polarisation (CP) in both frequency bands is obtained. The fabricated prototype of the proposed SIW antenna shows impedance bandwidth (IBW) of 15.36% (22.60–26.36 GHz; BandI) and 4.64% (29.04–30.42 GHz; BandII). The completely overlapping axial-ratio bandwidth (ARBW) with IBW of 15.16% (22.62–26.33 GHz) and 3.10% (29.20–30.12 GHz) with a peak gain of 12.47 and 7.71 dBi is obtained in BandI and Band II, respectively. The proposed antenna shows front-to-back ratio (FBR) of more than 20 dB in both resonating frequency bands. The measured results of the proposed MIMO antenna agree well with the simulation.

A triple-band dual-fed frequency-flexible SIW cavity-backed slot antenna

AbstractThis article presents a novel dual-fed triple-frequency bands antenna using quarter-mode (QM)/ Eight-mode (EM) substrate integrated waveguide (SIW) cavity resonators. A V-shaped slot is etched into the patch to divide the half-mode cavity into one QM and two EM cavities. One section of the EM cavity and QM cavity are excited with the help of individual micro-strip feedlines. This configuration yields two distinct frequency bands at 4.85 GHz due to TE110 mode of the EMSIW cavity and 5.87 GHz due to TE110 mode of the QMSIW cavity confirming the self-diplexing property. Later, when both the EM cavity sections are joined with the help of two metallic strips, an additional resonance appears at 7.34 GHz due to the excitation of TE120 mode. As compared to the conventional counterparts, the proposed structure is compact and simple. The footprint of the top patch is 0.6λ1 × 0.3λ1. To authenticate the proposed idea, the design is experimentally verified, and the measured results show a good covenant with the simulated results.

Development of a wideband hexagonal SIW cavity-backed slot antenna array

In this paper a novel wideband hexagonal cavity-backed slot antenna array using two sots including Resonant Narrow Slot (RNS) and Non-Resonant Wide Slots (NRWS) based on Substrate Integrated Waveguide (SIW) is proposed. First, a single element low profile wideband linearly polarized cavity-backed antenna using two slots is designed and analyzed. The antenna bandwidth is increased by NRWS, which makes both hybrid modes of TM110 and TM210 close to each other to be excited. Then, to improve antenna gain, an array of two elements cavity-backed slot including is designed and investigated. Moreover, in order to match the input impedance over the operating bandwidth, a special power divider using tapered line is introduced. The proposed single element and antenna array is made and successfully tested. The simulation and measurement results are in a good agreement for both single and antenna array. The measured gain and impedance bandwidth are 12 dBi and 14% respectively for the designed array.

Investigation of SIW Cavity-Backed Slot and Patch Antennas With Conical Radiation Patterns

Substrate integrated waveguide (SIW) cavity-backed slot and patch antennas with conical radiation patterns are investigated. In a center-fed SIW circular cavity with the top wall removed, a series of cavity modes with conical radiation patterns can be excited, wherein the lowest two modes are the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> modes. The cavity-backed slot antenna with either of the two modes can work independently, but the bandwidth is narrow. In order to improve the bandwidth, an SIW cavity-backed gap-coupled patch antenna is proposed. The antenna has a wide triple-resonance bandwidth, which includes the patch TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> mode, and the cavity TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> modes. The working principle and the mode characteristics are investigated. The antenna is designed, fabricated, and measured. Measurement results show that the antenna has a wide bandwidth of 64.6%. In the operation band, the antenna has a low reflection coefficient below -10 dB and provides a conical radiation pattern.

Self-Quadruplexing Circularly Polarized SIW Cavity-Backed Slot Antennas

In this communication, three self-quadruplexing circularly polarized (CP) antennas are presented in substrate integrated waveguide (SIW) technology for quad-band wireless services. The proposed antennas radiate from four unequal length T-shape slots etched on a square SIW cavity. The antennas are excited by four microstrip lines. The T-shape slot placed at each corner of the cavity creates orthogonal electric fields having 90° phase difference, which leads to CP radiation. The first antenna provides left hand circular polarization (LHCP), while the second antenna provides right hand circular polarization (RHCP) in all the bands. The third antenna offers LHCP in two bands and RHCP in other two bands. The sense of polarization can be changed by simply changing the slot orientation. Furthermore, the bands can be tuned almost independently over a wide range of frequency. For all the antennas, the measured isolations among the ports are more than 26 dB, front-to-back ratio (FTBR) is more than 15 dB, and the measured gain is at least 5.2 dBi.

A novel substrate integrated waveguide cavity‐backed self‐diplexing antenna array with frequency beam scanning characteristic

This article presented a substrate integrated waveguide (SIW) cavity-backed self-diplexing antenna array with frequency beam scanning characteristic. The proposed array consists of 16 SIW cavity-backed slot antennas. The SIW cavity-backed slot antenna can be fed by two separate ports to resonate at two different frequencies and achieve high isolation better than 20 dB between two input ports. The proposed element is a typical self-diplexing antenna. These cavity-backed slot antennas are shunt-fed by a compact 1 to 16 SIW power divider and series-fed by a set of microstrip lines, respectively. As a result, this array achieves an unidirectional radiation pattern at 10.2 GHz with high gain of 15.10 dBi, and a frequency beam scanning characteristic from 7.0 to 9.0 GHz ranging from −50° to 46°.

Characterization and Design of Wideband Penta- and Hepta-Resonance SIW Elliptical Cavity-Backed Slot Antennas

Substrate integrated waveguide (SIW) elliptical cavity-backed slot antennas (CBSAs) with either penta- or hepta-resonance are characterized and designed for wideband performance in this paper. First, the resonant behavior of the elliptical cavity is explored. Then the SIW CBSA with penta-resonance is designed by introducing a cross-shaped slot and a pair of unbalanced shorting vias into the cavity to excite two additional odd- and even- half degenerate quasi-TM 110 modes, besides other three modes of half quasi-TM 010 , and odd- and even- quasi-TM 110 . Further, by adding another pair of unbalanced shorting vias, two extra higher-order modes, i.e., odd- and even- quasi-TM 210 modes are successfully introduced to design a hepta-resonance antenna. The corresponding mode analysis and design guidelines are discussed in detail. Two prototypes are fabricated and measured at X-band, exhibiting the measured bandwidths of 21.8% and 22.7%, respectively. Measured results agree well with simulations, thus validating the design concept.

Circularly Polarized Self-Diplexing SIW Cavity Backed Slot Antennas

In this communication, three novel self-diplexing circularly polarized (CP) antenna configurations are presented in substrate integrated waveguide (SIW) technology for dual-band communication systems. The antennas provide left-hand circular polarization (LHCP), right-hand circular polarization (RHCP), and different sense of polarization at two bands. An asymmetric cross-slot on top of a rectangular SIW cavity is used as the basic radiator. A different sense of polarizations over the bands is obtained by changing the feed position and the slot orientation. The CP bands can be tuned independently. In each case, 3 dB axial ratio bandwidth is at least 0.81%. Working principle of the antennas is explained with the help of full-wave electromagnetic simulations. Finally, the three $X$ -band prototype antennas are fabricated and tested for experimental validation. All of them have high front-to-back ratio (FTBR) and low cross-polarization level.

Wideband Slot Antenna Backed by Cylindrical Substrate-Integrated Waveguide Cavity

A cylindrical substrate-integrated waveguide cavity-backed slot antenna is presented in this paper, which is devised for wideband operation. The fundamental and critical approach to generate a wide antenna bandwidth performance, in this case, is to merge three basic resonant modes (TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">010</sub> , TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> , and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</sub> modes) of the cylindrical cavity. In this paper, a fractional impedance bandwidth of 60% with S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> < −10 dB from 8 to 14.8 GHz has been achieved through this scheme. This antenna has a 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">$0.33\lambda $ </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">$\lambda $ </tex-math></inline-formula> denotes the space wavelength corresponding to the operating center frequency <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f =11.25$ </tex-math></inline-formula> GHz in this demonstration), which is found suitable for many wireless applications. Its resulting simple structure is definitely of benefit to the fabrication and integration with other front-end parts. The proposed antenna exhibits a broadside radiation pattern, which is stable within the operating frequency band of interest. The simulated radiation efficiency is above 85%. The antenna has been fabricated and experimentally verified. Measured results show a good agreement with simulated counterparts.

Broadband Planar SIW Cavity-Backed Slot Antennas Aided by Unbalanced Shorting Vias

Two types of substrate integrated waveguide (SIW) cavity-backed slot (CBS) antennas are proposed for bandwidth enhancement. First, a quad-resonance SIW CBS antenna is proposed using a cross-shaped slot and loading unbalanced shorting vias. Additional half- $\textrm {TE}_{120}$ mode is successfully excited along with three other independent modes including half- $\textrm {TE}_{110}$ and odd and even $\textrm {TE}_{210}$ modes. Next, a penta-resonance SIW CBS antenna with a cross-shaped slot is proposed, in which two pairs of shorting vias are loaded. Two additional hybrid modes of half- $\textrm {TE}_{210}$ and half- $\textrm {TE}_{120}$ modes are introduced along with three other independent modes including half- $\textrm {TE}_{110}$ and odd and even $\textrm {TE}_{310}$ modes. Furthermore, the working mechanism of these two types of SIW CBS antennas is explained. Finally, prototypes of these two antennas are fabricated and measured at X -band. Their measured fractional bandwidths are $\text{20.0}\%$ and $\text{20.8}\%$ , respectively. Simulation and measurement results agree very well, which confirms the validity of the proposed designs.

Gain-enhanced SIW cavity-backed slot antenna by using TE410 mode resonance

A gain-enhanced low profile substrate integrated waveguide (SIW) cavity-backed slot antenna is presented in this paper. By etching three parallel transverse slots on the center and both edges of the rectangular SIW cavity as the radiating elements, higher resonance mode of TE410 can be excited to achieve gain enhancement. Radiating mechanism and parameter effects of the three radiating slots have been investigated. Using the proposed multi-slot structures, an antenna is designed, fabricated and characterized, respectively. The fabricated antenna demonstrated a gain of 9.2 dBi, a front-to-back ratio of 17 dB, and a maximum cross-polarized radiation level of −19.7 dB at 10 GHz. Furthermore, the proposed antenna constructed using a single-layer printed circuit board (PCB) yields a better radiation performance and configuration advantage over that of the conventional planar antenna by taking advantage of the TE410 cavity resonance.

A Self-Triplexing SIW Cavity-Backed Slot Antenna

In this letter, a new design of self-triplexing slot antenna using substrate integrated waveguide (SIW) technique is demonstrated for multiband communication systems. The proposed antenna operates at triple frequency bands (around 6.53, 7.65, and 9.09 GHz) simultaneously utilizing a slot inserted on the top of the SIW cavity and is excited by three separate microstrip lines. By properly optimizing the antenna parameters, an isolation of better than 19 dB is realized between any two input ports, which helps to achieve self-triplexing property. The proposed triplexing antenna preserves simplicity, compactness, and a planar configuration that makes it suitable for highly integrated handheld devices. To demonstrate the significance of the proposed work, the antenna is prototyped, and experimental results show a close agreement with simulations. Moreover, the proposed antenna exhibits the measured gain of 3.1, 4.7, and 3.9 dBi at resonant frequencies with stable radiation patterns.

SIW antennas as hybrid energy harvesting and power management platforms for the internet of things

A novel antenna-harvester co-design paradigm is presented for wireless nodes operating in an Internet of Things context. The strategy leads to compact and highly-integrated units, which are able to set up a reliable and energy-efficient wireless communication link, and to simultaneously harvest energy from up to three different sources, including thermal body energy, solar, and artificial light. The core of the unit consists of a substrate-integrated-waveguide (SIW) antenna. Its surface serves as a platform for the flexible energy-harvesting hardware, which also comprises the power management system. To demonstrate the approach, two different SIW cavity-backed slot antennas and a novel compact dual linearly polarized SIW antenna are presented. These topologies facilitate the integration of additional hardware without degrading performance. In the meantime, they enable comfortable integration into garments or unobtrusive embedding into floors or walls. Measurements on prototypes validate the integration procedure by verifying that the integrated hardware has a negligible influence on the performance of all discussed SIW antennas. Finally, measurements in four well-chosen indoor scenarios demonstrate that a hybrid energy-harvesting approach is necessary to obtain a more continuous flow and a higher amount of scavenged energy, leading to a higher system autonomy and/or reduced battery size.

Hybrid MoM–PO analysis of multilayered SIW slot antenna with a dielectric slab radome

A fast and efficient full-wave hybrid method for the analysis of a multilayered substrate integrated waveguide (SIW) based slot antenna/array radiating into a dielectric slab radome is presented. The antenna structure is modeled as a stacked parallel-plate waveguide hosting metallic posts and coupling and/or radiating slots. To account the radome effects on the SIW antenna, the physical optics method in conjunction with three-dimensional ray trace technique are used to analyze a dielectric slab radome staked on the aperture of the antenna. The field in the SIW structure is expressed by using an expansion in terms of vectorial cylindrical eigenfunctions. Enforcing the boundary conditions on posts yield the scattering amplitude, while slots are modeled as unknown magnetic currents which are found by solving the integral equation derived from the continuity of the field on the slot surface. A double-layered SIW cavity backed slot antenna radiating into a dielectric slab radome is analyzed, and the results compared with high frequency simulation software (HFSS) simulations. It will be shown that the proposed method is fast and efficient and gives results in very good agreement with the most common simulation tools.

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.

Wideband LTCC 60-GHz Antenna Array With a Dual-Resonant Slot and Patch Structure

This paper presents a wideband 60-GHz antenna array with a dual-resonant slot-patch structure. A multilayered low-temperature co-fired ceramic substrate was used for antenna fabrication. A half-wavelength resonant slot was designed with a backed substrate-integrated waveguide (SIW) cavity to enhance the front radiation. The inverted microstrip center-fed structure was designed for easy signal excitation and superior impedance matching. A parasitic patch was also applied to enhance for bandwidth and gain enhancement. The effects of the SIW cavity-backed slot antenna with and without parasitic patches were empirically examined. The simulated results show that adding parasitic patches increased the resonance of the poles and improved antenna gain by 1.85 dB and bandwidth by 9%. A 2 × 2 dual-resonant slot-patch antenna array was designed to further enhance the gain and bandwidth. The equipment setup for on-chip measurements of gain and radiation patterns was established. The measured S11 showed a wide bandwidth of 23%. The measured gain for the four-element antenna array was 9 dBi with slight fluctuations over the 57-64-GHz frequency range.

Bandwidth-Enhanced Low-Profile Cavity-Backed Slot Antenna by Using Hybrid SIW Cavity Modes

A bandwidth enhanced method of a low-profile substrate integrated waveguide (SIW) cavity-backed slot antenna is presented in this paper. Bandwidth enhancement is achieved by simultaneously exciting two hybrid modes in the SIW-backed cavity and merging them within the required frequency range. These two hybrid modes, whose dominant fields are located in different half parts of the SIW cavity, are two different combinations of the and resonances. This design method has been validated by experiments. Compared with those of a previously presented SIW cavity-backed slot antenna, fractional impedance bandwidth of the proposed antenna is enhanced from 1.4% to 6.3%, its gain and radiation efficiency are also slightly improved to 6.0 dBi and 90%, and its SIW cavity size is reduced about 30%. The proposed antenna exhibits low cross polarization level and high front to back ratio. It still retains advantages of low-profile, low fabrication cost, and easy integration with planar circuits.

A Gain Enhanced Cavity Backed Slot Antenna using High Order Cavity Resonance

A gain enhanced method of substrate integrated waveguide (SIW) cavity backed slot antenna by using a high order cavity resonance has been presented in this paper. When the TE220 resonance is excited in the SIW cavity, a high gain radiation with the gain of 8.1 dBi can be achieved, which is about 2.7 dB higher than that of the previously presented SIW cavity backed slot antenna by using the TE120 or TE210 resonance. This design method can be extended to using the higher order cavity resonances such as TE230, TE330 and TE440 etc. to get a much higher gain radiation. Compared with an antenna array which has the same gain, the proposed antenna has advantages of simple feed network and more compact size.