Cavity-backed Slot Antenna Array Research Articles

Contactless Air-Filled Substrate Integrated Cavity-Backed Slot Antenna Array With Improved Printed Ridge Gap Waveguide Feeding Network

Contactless Air-Filled Substrate Integrated Cavity-Backed Slot Antenna Array With Improved Printed Ridge Gap Waveguide Feeding Network

A Substrate-Integrated Cavity-Backed Slot Antenna Array in Y-Band

A Substrate-Integrated Cavity-Backed Slot Antenna Array in <i>Y</i>-Band

Design and Performance Evaluation of Cavity-Backed SIW Antenna for Monopulse Applications

The design of a cavity-backed substrate integrated waveguide (SIW) dual-plane antenna for monopulse application is presented in this publication. The primary objective is to create a four-element circularly polarized cavity-backed slot antenna array that is compact and highly efficient. Two antenna subarrays are utilized to develop a complete analysis, design, and implementation of an antenna, and each antenna element can be used as an independent antenna for monopulse applications. The antenna element is made up of two square ring slot antenna components, a power divider, and a feed point. To produce sum and difference signals, the feed point of each antenna element can be connected to one of the input ports on a monopulse comparator. The antenna's performance at 10 GHz was assessed regarding radiation pattern, gain, return loss, bandwidth, axial ratio, and efficiency. A high-frequency structure simulator (HFSS) simulates a complete planar and compact SIW structure with a footprint of 61.6 mm x 58.1 mm. With a permittivity of 3.55 and a thickness of 1.524 mm, an antenna is manufactured using a photo-lithographic process on a single-layer Rogers RO4003 substrate. As per experimental findings, the antenna has a return loss of -40.17 dB, an RL bandwidth of 395 MHz, a gain of 13.11 dB, an axial ratio of 2.97 dB, and an efficiency of 89.85% at a frequency of 9.92 GHz. Experimental findings reveal exceptional performance parameters for the designed antenna, which can be used for monopulse applications at 10 GHz.

Development of a Broadband and High-Gain Circularly Polarized Array of Multilayer Slot Antennas for X-Band Wireless Communication Networks

This paper presents a wideband cavity-backed slot antenna array designed for X-band wireless communication systems. The antenna element consists of a circular slot combined with a cross-slotted patch; both are fed by an L-shaped microstrip line through proximity coupling to extend the impedance bandwidth and gain. The reduction of beam squint in the radiation patterns, caused by the asymmetric feed line, is achieved through intelligent optimization of the dimensions and position of the cross slot on the patch. Additionally, a back cavity is included to provide unidirectional radiation and enhance gain. The antenna exhibits right-hand circularly polarized (RHCP) radiation patterns with high gain over a wideband frequency range. To further improve the axial ratio (AR) bandwidth and gain, the antenna is utilized in a 2 × 2 array configuration with a sequential rotation feed network. The overall dimensions of the proposed array are 1.42 λ 0 × 1.42 λ 0 × 0.45 λ 0 , where λ 0 represents the wavelength at the center frequency of 10 GHz. The fabricated array is then tested, and the measurements show an impedance bandwidth of 60% (7 GHz-13 GHz) with S 11 &lt; − 10 dB, a 3 dB AR bandwidth of 42% (7.45-11.65 GHz), and a peak gain of 11.14 dB. The simulated and measured results exhibit good agreement, validating the effectiveness of the design.

Reconfigurable Full-Metal Circularly-Polarized Cavity-Backed Slot Antenna and Array With Frequency and Polarization Agility

In this brief, reconfigurable circularly-polarized (CP) cavity-backed slot antenna (CBSA) and antenna array with frequency and polarization agility are proposed. Two degenerate modes TE101 and TE011 are respectively perturbed by the metal posts along y-axis (named as MP-1) and x-axis (named as MP-2), and independent frequency tuning is obtained. Then, two crossed slots are placed on the top wall to radiate the electromagnetic energy of TE101 and TE011 modes, respectively. In this context, circular polarization can be realized by setting different lengths of MP-1 and MP-2. Besides, reconfigurable polarization between left-hand and right-hand circular polarization can be realized by exchanging the lengths of MP-1 and MP-2. Meanwhile, reconfigurable operating frequency can be realized by simultaneously increasing or decreasing the lengths of MP-1 and MP-2. In addition, a reconfigurable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4{\times }4$ </tex-math></inline-formula> CP array without introducing power dividers and without increasing the number of tuning metal posts is further investigated. Finally, the reconfigurable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4{\times }4$ </tex-math></inline-formula> CP array is fabricated and tested. Reconfigurable frequency, reconfigurable polarization, high total efficiency, and stable radiation pattern are simultaneously obtained. Good agreement between measured and simulated results well validates the proposed design concept.

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.

Ultra-Wideband, Compact, and High-Gain Two-Port Antenna System for Full-Duplex Applications

A broadband, dual-polarized, and common-aperture <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> cavity-backed slot antenna (CBSA) array for enabling full-duplex wireless communication is presented. The antenna consists of a thin rectangular cavity appropriately loaded with metallic septa to excite multiple resonances of similar desired field distribution to achieve consistent radiation characteristics over a wide bandwidth. Four pairs of concentric orthogonal radiating slots are cut out on one of the broad walls of the cavity all of which are fed by two concentric orthogonal slots on the opposite broad wall of the cavity. The cavity is fed by an end-launch coaxial-to-waveguide transition to excite one of the channels. The other channel is excited by a two-pronged microstrip line symmetrically crossing over the other cavity feeding slot. Due to the out-of-phase coupling from the two prongs of the microstrip line to the other port, this type of excitation is shown to provide an unprecedented level of isolation between the two channels over a wide bandwidth. To achieve a high-efficiency and fabrication accuracy of this complex architecture, the antenna is 3-D printed out of HP PA12 Nylon and is then metalized by the silver spraying technology. The fabricated antenna provides a minimum of 55 dB of isolation and 8 dB of return loss over 44% fractional bandwidth from 4.8 to 7.5 GHz. Keeping its size smaller than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.3 \lambda _{L} \times 1.3\lambda _{L} \times 0.27\lambda L$ </tex-math></inline-formula> (where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{L}$ </tex-math></inline-formula> is the free space wavelength at the lowest frequency), and its weight less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$70g$ </tex-math></inline-formula> , the antenna provides a minimum gain of 10 dB for both polarizations and exhibits more than 20 dB polarization discrimination within the main beam over the entire band.

Low-Sidelobe Cavity-Backed Slot Antenna Array With Simplified Feeding Structure for Vehicular Communications

In this article, low-sidelobe cavity-backed slot antenna array with simplified feeding structure for vehicular communication is proposed. Conventional low-sidelobe antennas were realized using power dividing network to obtain the in-phase and nonuniform-amplitude excitation, which causes complicated antenna's structure and design. To tackle these challenges, a simplified feeding method without using power dividing network is introduced to design the low-sidelobe slot antenna array. The slots at the top walls serve as the radiation elements, and the slots are directly fed by the electric field of the cavity mode. Nonuniform amplitude is obtained by simply modifying the slots' sizes and positions, while the in-phase excitation of the elements is remained. The nonuse of power dividers brings out a simpler antenna structure than conventional full-metal waveguide-based antennas. Besides, the full-metal structure introduces a high power-handling capacity. Then, two linear arrays with 1 × 4, 1 × 7 elements and a planar array with 5×4 elements are presented to show the design feasibility. Finally, the 5 × 4 antenna array is fabricated and measured, which can achieve 18.2 dBi gain, -20 dB sidelobe level, 94% radiation efficiency, and -42 dB cross-polarization. Good agreement between measurement and simulation verifies the feasibility of the proposed design concept.

High-Efficiency and Wideband Dual-Resonance Full-Metal Cavity-Backed Slot Antenna Array

A dual-resonance wideband full-metal cavity-backed slot antenna array (CBSA) with high efficiency is proposed. A cavity mode and a resonant-iris mode are used to produce a wide impedance bandwidth. Radiation slots (elements) placed on the top wall are directly fed by electric fields of the modes using a single feeding slot without extra structures. This simplified feeding structure can reduce the antenna complexity, and can also improve the radiation efficiency by reducing power loss along with the conventional feeding power dividers. Thereafter, two wideband and high-efficiency slot arrays with 2 × 2 and 4 × 4 elements are designed based on these two cavity modes and proposed a simplified feeding structure. The measurement of 2 × 2 slot array shows that the proposed 2 × 2 slot antenna array can achieve 15% bandwidth, 13.4 dBi peak gain, and 95% total efficiency.

A 20-Element Cavity-Backed Slot Electronically Steerable Parasitic Array Radiator (ESPAR) With 2-D Beamsteering and Minimized Beam Squint

A 20-element cavity-backed slot antenna array is presented herein based on an electronically steerable parasitic array radiator (ESPAR) cross subarray. This ESPAR array is able to steer the main beam within ±45° in the E-plane and ±40° in the H-plane without grating lobes. Inside each subarray, the beamsteering is realized by tuning the reactance of the loads at the four parasitic elements. Therefore, only four phase shifters are needed for this 20-element array to achieve 2-D beamsteering, corresponding to an 80% reduction on the number of phase shifters compared to a classic phased array. The measured impedance matching is maintained below -10 dB from 6.0 to 6.4 GHz (6.4% fractional bandwidth) at all scan angles. The radiation patterns are measured at five different scan angles in E- and H-planes. At each scan angle, the measured radiation patterns at five frequencies across the impedance-matching bandwidth exhibit very small beam squint. The measured peak gain is found to be 14.0 dBi at the boresight direction.

Active Phased Array of Cavity-Backed Slot Antennas With Modified Feeding Structure for the Applications of Direction-of-Arrival Estimation

This communication presents a cavity-backed slot antenna (CBSA) array for the estimation of direction of arrival (DOA). This new CBSA employs an alternative feeding structure to excite the radiation of cavity-backed slots and transfer the area for RF module implementation from the front surface of the array aperture to the bottom behind the cavity. This backfeeding design allows the accommodation of active RF modules inserted from the bottom behind the antenna aperture, and avoids interfering with the antenna radiation. The new feeding structure may also reduce the depth of the metal cavity and, in turn, decrease the thickness and weight of antennas in the phased array composition to make a compact array with a low profile. The bandwidth is found to be larger than that of a conventional CBSA. The antenna array for the DOA estimation has been prototyped with 32 elements. Experimental data and numerical simulation results are presented to validate the proposed antenna design concepts.

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.

A 16‐element corporate‐feed multilayer SIW cavity‐backed slot antenna array

In this study, a 16-element multilayer substrate integrated waveguide (SIW) cavity-backed slot antenna array is investigated. In order to broaden the operating bandwidth of SIW slot antenna, multilayer cavities with gradually decreased permittivity and expanded aperture sizes are loaded above the slot, which realises a smooth transition between SIW slot and free space. A corporate-feed method using slot coupling is designed to excite the array elements. Measured results indicate that the fabricated array operates with 26.5% bandwidth ranging from 22.9 to 29.8 GHz. Besides, stable broadside radiation patterns are obtained across the operating band. Moreover, the proposed array can be easily expanded to a large-scale array, which will greatly satisfy the requirements of sufficient bandwidth and high radiation performance in modern communication systems.

A microfabricated low-profile wideband antenna array for terahertz communications

While terahertz communications are considered to be the future solutions for the increasing demands on bandwidth, terahertz equivalents of radio frequency front-end components have not been realized. It remains challenging to achieve wideband, low profile antenna arrays with highly directive beams of radiation. Here, based on the complementary antenna approach, a wideband 2 × 2 cavity-backed slot antenna array with a corrugated surface is proposed. The approach is based on a unidirectional antenna with a cardiac radiation pattern and stable frequency characteristics that is achieved by integrating a series-resonant electric dipole with a parallel-resonant magnetic dipole. In this design, the slots work as magnetic dipoles while the corrugated surface radiates as an array of electric dipoles. The proposed antenna is realized at 1 THz operating frequency by stacking multiple metallized layers using the microfabrication technology. S-parameter measurements of this terahertz low-profile metallic antenna array demonstrate high efficiency at terahertz frequencies. Fractional bandwidth and gain are measured to be 26% and 14 dBi which are consistent with the simulated results. The proposed antenna can be used as the building block for larger antenna arrays with more directive beams, paving the way to develop high gain low-profile antennas for future communication needs.

Design and Fabrication of a High-Gain 60-GHz Cavity-Backed Slot Antenna Array Fed by Inverted Microstrip Gap Waveguide

This communication deals with the design of a $16\times 16$ slot array antenna fed by inverted microstrip gap waveguide (IMGW). The whole structure designed in this communication consists of radiating slots, a groove gap cavity layer, a distribution feeding network, and a transition from standard WR-15 waveguide to the IMGW. First, a $2\times 2$ cavity-backed slot subarray is designed with periodic boundary condition to achieve good performances of radiation pattern and directivity. Then, a complete IMGW feeding network with a transition from WR-15 rectangular waveguide to the IMGW has been realized to excite the radiating slots. The complete antenna array is designed at 60-GHz frequency band and fabricated using Electrical Discharging Machining Technology. The measurements show that the antenna has a 16.95% bandwidth covering 54–64-GHz frequency range. The measured gain of the antenna is more than 28 dBi with the efficiency higher than 40% covering 54–64-GHz frequency range.

Threefold Rotationally Symmetric SIW Antenna Array for Ultra-Short-Range MIMO Communication

A high-performance, three-element substrate-integrated-waveguide (SIW) cavity-backed slot antenna array that covers the (5.15-5.85) GHz band is designed for integration inside or underneath the worktop of a desk, to set up a stable, high data-rate ultra-short-range 3 × 3 multiple-input multiple-output (MIMO) wireless communication link with a mobile user (MU) positioned on top of that worktop. The antenna topology and array geometry are carefully selected to maximally exploit the multiplexing capabilities of the ultra-short-range 3 × 3 MIMO channel over a wide bandwidth, yielding an increased channel capacity and/or reduced power consumption. In addition, special care was taken to guarantee a channel capacity that is less dependent on the relative orientation of the MU. Furthermore, the SIW implementation technology is combined with innovative antenna materials to guarantee a low-profile, low-cost, stable, and high-performance broadband array design that maintains its excellent performance after integration. A prototype of the antenna array was fabricated, integrated according to two different integration scenarios, and validated. Measurements prove that the antenna array allows integration into a worktop with only a minor influence on its return loss and mutual coupling, guaranteeing a bandwidth of at least 1.078 GHz and a minimum isolation between antenna elements of 30 dB within the entire (5.15-5.85) GHz band.

A Design of Wide Band and Wide Beam Cavity-Backed Slot Antenna Array with Slant Polarization

Design of antenna array under the limitation of restricted size is a challenging problem. Cavity-backed slot antenna is widely used because of its advantages of small size, wide band, and wide beam. In this paper, a design of wide band and wide beam cavity-backed slot antenna array with the slant polarization is proposed. To obtain wide band and wide beam with limited size, the inverted microstrip-fed cavity-backed slot antenna (IMF-CBSA) is adopted as the element of 1 × 4 antenna array. The slant polarized antennas and their feeding networks are adopted because of their simple structures. The performance of the proposed antenna array is verified by the simulations and experiments. The measured VSWR &lt; 2 bandwidth is 55% at the center frequency 21.8 GHz, and the gain is larger than 12.2 dB. Experimental results demonstrate that the proposed design achieves wide band and beam with the size of 68 mm × 56 mm × 14.5 mm.

An SIW filtering antenna array with quasi-elliptic gain response based on intercavity bypass coupling

In this article, a filtering antenna array based on substrate integrated waveguide (SIW) is proposed with quasi-elliptic gain responses for the first time. Two radiation nulls in the gain responses at two sides of the frequency band edges are designed by applying a novel intercavity bypass coupling scheme. First, by carefully analyzing the bypass coupling between the in-band and out-of-band modes in a single oversized TE103 mode cavity resonator, quasi-elliptic filtering responses are achieved for a two-output filter. Afterward, those cavity resonators coupled with the two outputs are replaced by cavity-backed slot antennas to achieve the proposed filtering cavity-backed slot antenna array. Only one cavity is required in our design to achieve the two transmission zeros and the function of power divider. As a result, the complexity of the proposed filtering antenna array is reduced. A prototype operating at Ka band is designed, fabricated and measured with a center frequency of 28.5 GHz and fractional bandwidth of 1.25%. Similar characteristics can be observed between the gain response of the proposed filtering antenna and the transmission responses of the two-output filter. The proposed SIW filtering antenna array has great potential to be integrated into millimeter-wave transceiver modules. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:191–198, 2016.

Broadband Circularly Polarized Cavity Backed Slot Antenna Array with Broadband Sequential Rotation Feed

Broadband Circularly Polarized Cavity Backed Slot Antenna Array with Broadband Sequential Rotation Feed

Broadband Circularly Polarized Cavity-Backed Slot Antenna Array With Four Linearly Polarized Disks Located in a Single Circular Slot

A novel cavity-backed slot antenna array with broadband circularly polarized (CP) property is presented in this letter. A corporate feed network composed of three Wilkinson power dividers is applied to sequentially rotated feed four linearly polarized disks that are located in a cavity-backed circular slot. The measured 3-dB axial-ratio (AR) bandwidth of the array is 54.5%, and the 10-dB return loss bandwidth is 92.1%. The 3-dB gain bandwidth is about 50.8% with the peak gain 9.9 dBic.