Cavity-backed Antenna Research Articles

Compact Dual-Polarized Cavity-Backed Antenna With Wideband Performance for Deep Torso Imaging

Compact Dual-Polarized Cavity-Backed Antenna With Wideband Performance for Deep Torso Imaging

Simple Integration of Cavity-Backed Antenna with Patch Antenna for Developing Hybrid Antenna Using SIW Technology

This paper proposes a novel scheme for developing a linearly polarized (LP) hybrid antenna using a simple integration of a planner cavity-backed antenna with a conventional rectangular patch antenna. To substantiate, a half-mode rectangular substrate-integrated waveguide technique is divided into halves to reduce the size and later integrated with a patch antenna. The patch antenna is getting excited by the mutual coupling of TE101 mode and resonating in the vicinity of the cavity resonator. These two different combinations of strategy let the antenna obtain superior characteristics such as bandwidth and gain. To make this structure enable to use in the planner circuit, a 50 Ω microstrip line is incorporated. This proposed hybrid antenna is simulated and tested experimentally to justify its worthiness. The simulated and measured data maintained good agreements regarding S11, bandwidth, gain, radiation pattern, and efficiency.

Design and Implementation of Novel H-Shaped Self-Diplexing SIW Rectangular Cavity-Backed Antenna with Harmonic Suppression for Terrestrial Communications

A novel and low profile, planar, rectangular cavity-backed self-diplexing substrate integrated waveguide (SIW) antenna with H-shaped slot for dual-band wireless services was designed and demonstrated. The proposed antenna structure radiates from H-shaped slot, which is etched on top of the SIW rectangular cavity, and is excited by two separate 50 Ω microstrip feed lines. The H-shaped slot is a combination of two vertical slots and one horizontal slot; because of that the presented antenna radiates at two distinct frequency bands around 8.95 GHz and 10 GHz, simultaneously. The design methodology results show that the H-shaped slot is significantly more effective than various other slots in the proposed geometry to suppress the unwanted harmonics, attaining good impedance matching and bandwidths and achieving better isolation between these two ports. Hence, the complete design mechanism helped to achieve self-diplexing characteristics. Furthermore, a self-diplexing H-shaped SIW rectangular cavity-backed antenna was fabricated and characterized for the complete demonstration purpose and found good covenants between the simulated one. Measured results show that the presented designed has impedance bandwidths for the lower and upper frequency bands of around 2.0% (8.89–9.03 GHz) and 3.1% (10.01–10.32 GHz), respectively, and obtained maximum measured gain of 5.11 dBi and 5.41 dBi at 8.95 GHz and 10.15 GHz, respectively. The proposed self-diplexing SIW rectangular cavity-backed structure shows that front-to-back ratios (FTBRs) are more than 21 dB, and on the other side, it provides good isolation between the two ports, which is more than 20 dB.

A broadband low profile SIW cavity-backed antenna loaded with hexagonal and rectangular slots for ‘X’ band application

A broadband low profile SIW cavity-backed antenna loaded with hexagonal and rectangular slots for ‘X’ band application

Circularly polarized cavity-backed antenna with variable magneto-electric crossed-dipole structure

Circularly polarized cavity-backed antenna with variable magneto-electric crossed-dipole structure

Joint Microwave and Millimeter-Wave Antenna Design for UAV-Enabled Communications

Wireless communications aided by unmanned aerial vehicles (UAVs) have emerged as a promising technology for serving numerous terminal devices of the Internet of Things (IoT). To support such a broad range of emerging applications, millimeter-wave (mm-Wave) is an effective solution because it has the characteristics of high transmission efficiency, wide frequency band, and very low latency. Meanwhile, a UAV-assisted communication system also requires a global positioning system (GPS) reception (1.575 GHz) and ground control unit (2.4 GHz). This paper investigates a highly integrated multi-band antenna design to operate at the microwave (μ-Wave) and mm-Wave bands for robust and flexible UAV communications. Each antenna operating band utilizes the technology of a substrate-integrated waveguide (SIW) cavity-backed antenna. By strategically engineering an mm-Wave antenna into a 2.4 GHz band antenna to share the aperture, besides showing high aperture reuse efficiency with a large frequency ratio, the proposed antenna has also maintained the geometrical advantages of compactness, planar configuration, and ease of integration with other circuits. Furthermore, the proposed antenna can provide flexible radiation patterns with upper/lower-space signal coverage according to the mission demands of the UAV. Experimental results of the prototype show that the antenna can fully cover the 1.575 GHz, 2.4 GHz, and fifth-generation (5G) mm-Wave bands of n257, n258, and n261. Multiple bands and stable radiation characteristics indicate the proposed antenna's suitability for deploying a UAV-supported wireless network.

Wideband Low-RCS Step-Type Cavity-Backed Stacked Dielectric Resonator Antenna for Unmanned Aerial Vehicle Communications

This letter explains the design of a cavity-backed stacked dielectric resonator antenna (SDRA) with wider impedance bandwidth (IBW) and improved gain for C-band and S-band applications. The antenna mainly comprises of four dielectric resonators stacked above one another of varying size and shape. Combining the SDRA with step-type cavity and conformal radome forms the final antenna. The antenna provides a wider IBW of 103% (2.07–6.55 GHz), dual-band axial ratio bandwidth of 27.90% (2.38–3.15 GHz) and 16% (5.01–5.88 GHz), respectively. The antenna provides a maximum gain of 9 dBi. The final cavity-backed antenna offers a good radar cross-section reduction ranging from 2–8 GHz for both normal and oblique incidence angles. Hence the proposed SDRA with the dual-layer cavity is applicable for unmanned aerial vehicle communications.

A Typical Slotted SIW Cavity-backed Antenna for Dual frequency operations in U-NII Bands

A low profile circular shaped cavity-backed substrate integrated waveguide (SIW) antenna with two-typical intersecting rectangular slots on the ground plane is designed to operate in the dominant TM010 mode at a frequency of 5.19 GHz in U-NII-1 band for wireless applications. The initially designed antenna produces a gain of 4 dBi with a narrow impedance bandwidth extending from 5.17 – 5.22 GHz. The antenna design is further modified by insertion of another shifted two-typical intersecting rectangular slots to finally resemble that of Hash shape; resulting in dual band antenna operation at 4.9 and 5.93 GHz. The gains obtained are 3.7 dBi and 1.4 dBi for 4.9 and 5.93 GHz respectively with an impedance bandwidth covering 4.88 - 4.92 GHz and 5.92 – 5.94 GHz respectively. The antenna prototype is fabricated using Arlon AD270 substrate material. Parametric studies are performed in terms of return loss and gain of the antenna. All simulations are carried out using HFSS v19.0 and show similar behavior to their experimentally measured counterparts.

Gain Enhancement and Cross-Polarization Suppression of Cavity-Backed Antennas Using a Flared Ground Cavity and Iris.

Herein, we present new design principles for gain enhancement and cross-polarization suppression in dual-polarized cavity-backed antennas and demonstrate the capability in an octagonal cavity-backed open prism antenna (OCROP). In our approach, the gain is enhanced through an optimal flaring procedure and a novel metallic iris is used to control the electromagnetic fields and thereby reduce the cross-polarization. Previously, we investigated a dual-polarized OCROP antenna configuration and were able to simultaneously achieve 50% impedance bandwidth, 40% cross-polarization bandwidth (≤25 dB), and 10.2 dBi peak gain. In this study, we investigated gain enhancement by flaring an upper section of the ground cavity sidewalls, while maintaining a constant cavity height. Two cases were investigated: (1) the flare angle was modified, while the ratio of the non-flared to flared sidewall heights was kept constant, and (2) the ratio of the non-flared to flared sidewall heights was varied. In case 1, we established that, while increasing the flare angle results in a gain increase, there is a limit, as cross-polarization at the upper operating frequencies increases. In case 2, we were able to reduce the aperture phase error and achieve a higher peak gain of 12.8 dBi. To address the increased cross-polarization at the high frequency end when a large flare was used, we added a metallic iris at the junction of non-flared and flared sidewalls. We showed that increasing the iris width generally decreases the cross-polarization at high frequencies, without compromising the gain and impedance bandwidth. At an optimal width, it provides a nearly constant, low cross-polarization (below -25.8 dB) and a peak gain of 13.3 dBi, across the entire 50.7% impedance bandwidth of the antenna. We fabricated and successfully tested a prototype to verify the design and simulation approach. These results prove that incorporating an aperture flare with a metallic iris can significantly improve the gain and cross-polarization performance of cavity-backed antennas.

Circular polarization-agile and beam switching enabled reconfigurable cavity-backed antenna

In this paper, a circular polarization-agile and beam switching enabled reconfigurable cavity-backed antenna having the ability to steer its radiation beam in different directions is presented. The antenna consists of two E-shaped driven patches, a tunable phase shifter integrated with PIN diodes for pattern switching and four switchable feeding probes for implementing polarization agility. The proposed antenna can simultaneously change its polarization and pattern. Beam switching and polarization agility are independently controlled by altering the OFF-ON states of diodes loaded on the feed network and switchable feeding probes. For validity of the proposed concept, the antenna prototype is fabricated and tested. The proposed antenna has measured impedance bandwidth (S11 < -10 dB) and 3 dB axial ratio bandwidths of 23% and 17.4% respectively for all states over the frequency range 4.7–5.6 GHz. The measured and simulation results show that the antenna can scan up to ± 30° with five reconfigurable beams and two polarizations states for each reconfigurable beam.

Design and fabrication of multi-material broadband electromagnetic absorbers for use in cavity-backed antennas

We investigated the feasibility of designing and fabricating novel broadband radiofrequency (RF) absorbers for use in cavity-backed antennas. Fabricating the absorber involved a multi-material additive manufacturing (AM) approach that combined two polymer filaments: a low-loss dielectric filament and a lossy carbon-loaded filament. An iterative optimization algorithm was developed to deploy these filaments and create gradient distributions of material properties that minimize reflectance over a desired frequency band and a range of incident angles to achieve wideband electromagnetic absorption. The chosen material profiles were effectively realized using a spatially varying subwavelength lattice structure printed via fused filament fabrication. Experimentally, validation results demonstrated low reflectance over a wide frequency band, 10 to 40 GHz, and a range of incident angles, 0°–50°. Finally, this printed multi-material absorber was integrated within a cavity-backed spiral antenna and used to suppress backlobe radiation while maintaining an acceptable radiation pattern in the forward direction. While this study investigated cavity-backed antennas, these computational and experimental methods are potentially useful for a wide range of other applications.

Dual-band SIW cavity backed antenna loaded with CSRR metameterial

Dual-band SIW cavity backed antenna loaded with CSRR metameterial

Millimeter-Wave Phased Array Antenna Integrated With the Industry Design in 5G/B5G Smartphones

In this communication, a dual-polarized millimeter-wave (mmWave) phased array antenna is proposed for the fifth-generation (5G)/B5G smartphones. The configuration of the antenna array is highly integrated with the up-to-date industry design (ID) of ultranarrow side frame, 3-D curved display, and covers, which are widely adopted in flagship smartphones and popular among consumers. The proposed antenna contains a minor portion of slotted metal frame and a cavity-backed antenna module. The air cavity and the multiple slots are employed to enhance the bandwidth. A strip bump is established on the metal frame to meet the ID requirement, which also improves the impedance matching simultaneously. A prototype of the proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times $ </tex-math></inline-formula> 4 phased array assembled in a smartphone’s metal frame is fabricated and measured. The antenna array achieves a −10 dB impedance bandwidth from 23.2 to 29.7 GHz. At 27.0 GHz, the measured peak gain is greater than 11.2 dBi and the 3 dB scanning angle is larger than 77° for the two polarizations. Finally, the blockage issue of the curved cover is studied. In virtue of high integration with ID, compact size, wide bandwidth, good spatial coverage, and easy assembling, the proposed antenna scheme is promising for 5G/B5G smartphone designs.

Wideband Dual-Polarized Octagonal Cavity-Backed Antenna with Low Cross-Polarization and High Aperture Efficiency

Simultaneously enhancing multiple antenna performance parameters is a demanding task, especially with a challenging set of design goals. In this paper, by carefully deriving a compatible set of enhancement techniques, we propose a compact/lightweight/low-cost high-performance L-band octagonal cavity-backed hybrid antenna with multiple attractive features: dual-polarization, wide impedance bandwidth, low cross-polarization, high gain, and high aperture efficiency. The ground cavity is octagonal, which allows the antenna to have a small footprint, and, more importantly, low cross-polarization and high aperture efficiencies when compared to a commonly-used square design. The hybrid design relies on the resonance merging of two radiating elements, i.e., radiating feedlines and a conductive open prism, to form a wide impedance bandwidth. To permit polarization diversity and low cross-polarization, it is differentially and orthogonally fed. Herein, a series of parametric simulation studies on antenna configurations provide information on how to improve the impedance bandwidth and cross-polarization performance. To verify the simulation studies, an antenna prototype was fabricated and tested. Excellent agreement between the simulated and measured results was reached.

A Half-Mode Cavity Backed Hybrid Array Antenna Using Substrate Integrated Waveguide (SIW) Technology

This article proposes a hybrid array antenna where a cavity-backed antenna is used jointly with a patch antenna using half-mode substrate integrated waveguide technology (HMSIW) to reduce antenna size. This hybrid structure consists of a flexible Rogers RO4003C substrate ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\epsilon_{{r}} =3.55$ </tex-math></inline-formula> ) showing linearly polarized TE101 mode where the cross-polarization level (XPL) is less than −12 dBi. An inset feed has been utilized to excite the main cavity resonator, and later by proximity coupling, the parasitic patch is also excited in TE101 mode. By further dividing the outer patch, four new cases of antenna have emerged, and comprehensive investigations on their parameters based on simulation have been presented. It paints an upgrade of the antenna’s performance. As per simulations, further dividing of the patch helps to bring out positive changes in the antenna’s performance by escalating gain, bandwidth (BW), and efficiencies while also lessening XPL, sidelobe levels (SLLs), and associated loss up to a satisfying level. The proposed antenna is then fabricated and experimentally validated in its theoretical analysis. A couple of experimentally validated parameters make this fabricated sample suitable for wireless application and maintain good agreement with numerical simulation. CST Microwave Studio and HFSS carried out the associated numerical simulation.

A Conical Cavity-Backed Antenna With Embedded Multiple Quarter-Wave Resonators

A Conical Cavity-Backed Antenna With Embedded Multiple Quarter-Wave Resonators

A Dual-Wideband Cavity-Backed Antenna by Using Waveguide Transition and Short-Ended Groove Loading

A novel scheme is presented to control the frequency response on an open-ended waveguide antenna. A groove is loaded in the waveguide that is used to independently control the frequency response of the antenna without affecting the radiation pattern, and a transition is used to provide additional control. A dual-wideband antenna is taken as an example to verify the effectiveness of the scheme. To demonstrate the idea, an antenna element and its <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times2$ </tex-math></inline-formula> array were designed, fabricated, and measured. Reasonable agreement between the measured and simulated results has been observed. The measured 10 dB impedance bandwidths of the lower and upper bands of the proposed element are achieved to be more than 22.2% and 14.2%, respectively, fully covering the 26/28 GHz band (24.25–29.5 GHz) and 39 GHz (37–40 GHz) band.

A W-Band High Radiation Efficiency With BCB-Air Cavity-Backed Antenna Based on Through Silicon Ring Trench

The design of a W-band BCB-air cavity-backed antennas is presented in this letter. The three-dimensional (3-D) capacitance model of the cavity-backed structure is analyzed and the design methodology is illustrated in detail. The proposed antenna is fabricated by using our in-house silicon-based MEMS photosensitive composite film fabrication process by combining localized backside etching technology and through silicon ring trench. The measured impedance bandwidth (−10 dB) of the antenna is from 88.9 to 93.7 GHz with a maximum gain 8.2 dBi and 95% radiation efficiency at 91 GHz, higher the gain and radiation efficiency by 2.2 dB and 35%, respectively, as compared with the case without TSRT. The measured results show close agreement with the simulated results. The proposed antenna can be further 3-D heterogeneously integrated with other components because of low interconnection loss to enhance the high-frequency performance for future millimeter wave radar and communication systems.

A Dual Circularly Polarized SIW-Fed Phased Array Antenna With Wide-Angle Beam Scanning Range

We propose a dual circularly polarized (CP) substrate integrated waveguide (SIW) cavity-backed antenna with wide axial ratio (AR) beamwidth, which can generate the right-hand CP (RHCP) or left-hand CP (LHCP) radiation through exciting different ports. Dual CP radiations are accomplished by an SIW directional coupler (DC) in the bottom layer, which provides the desired amplitude and phase conditions for two orthogonal slots. By superposing phase centers of linearly polarized (LP) electric field elements, the proposed antenna achieves a good performance of 3 dB AR beamwidth of 165° in the desired azimuth cut plane. Furthermore, an eight-element dual CP linear phased array with a wide-angle beam scanning ability is comprised by this antenna prototype. Numerical and measured results show that the array antenna can scan its main lobe from – 59° to 58°. In general, the proposed antenna array fed by the SIW structure satisfies the requirement of a multipolarization wireless communication system for low profile, simple structure, and easy integration with planar circuits.

Derivation of a Universally Valid Array Factor of a Conformal Arrays Based on Phase Compensation and Genetic Learning Particle Swarm Optimization

In this study, we investigated the recent deterioration of the radiation pattern performance of conformal arrays, which are applied to fields such as aircraft and vehicles. We analyzed the radiation pattern of conformal arrays in the array factor stage by combining previous studies on various beam-forming techniques for conformal arrays. To efficiently calculate and utilize the radiation pattern of conformal arrays, we derived an array factor based on phase composition for nonplanar arrays of three-dimensional (3D) coordinate systems. As an amplitude tapering method for controlling the sidelobe level of the derived 3D array factor, we propose a Bernstein polynomial generalization method based on Genetic Learning Particle Swarm Optimization. The proposed 3D array factor was verified using a cavity-backed patch antenna operating at the X-band through EM simulation of conformal arrays as a single element.