Cavity Antenna Research Articles

Microwave cavity antenna for automatic detection of chicken breast muscles affected by wooden breast defect

Over the past years, artificial selection for meat-type (broiler) chickens has resulted in improved production efficiency, but also in an increased incidence of skeletal muscle abnormalities. In particular, wooden breast (WB) abnormality causes abrupt changes in meat quality and enormous economic losses. Thus, the poultry processing industry requires a reliable method to detect the abnormality in production lines in a non-destructive and contactless way. The present research aimed to evaluate the effect of WB on dielectric properties to develop a potential online technique to distinguish unaffected from affected breasts. Sixty-five pectoralis major muscles were picked 3 h post-mortem from the same flock (42-day-old broilers, 2.8 kg average live weight) and classified by visual inspection according to their phenotype as normal (N, not showing not any signs of the WB condition; n = 33) or WB (exhibiting extensive hardened areas and stiffness perceived by manual palpation throughout the entire fillet; n = 32). WB muscles exhibited remarkably higher values of dielectric constant and loss factor in a wide range of the explored frequencies (200 MHz–14 GHz), suggesting higher water mobility and a higher solvate capacity; this makes the electromagnetic technique for classification promising. Based on the above evidence, a rapid microwave electric technique in the range 1.5 GHz–3 GHz was developed for the online detection of WB. Indeed, combining the use of a cavity antenna (vector network analyzer instrumental chain with partial least square – discriminant analysis), this technique correctly classified 100% of the validation test set.

Gain improvement of HMSIW Antenna with SRRs

A novel integrated waveguide-backed cavity antenna, optimized for wireless communication systems operating at 5.8 GHz, is presented in this paper. The antenna design process is elaborated upon, emphasizing the incorporation of a high-gain substrate to enhance performance. At the target frequency of 5.8 GHz, the half-mode substrate integrated waveguide cavity antenna achieves a gain of 4.79 dB. Notably, the antenna design integrates two Split Ring Resonators strategically positioned at the periphery of the semi-circular patch to further augment gain. The design and simulation of antenna are done using high frequency software simulation version ANSYSEM17.2. Experimental validation of the simulation results is conducted through the fabrication of a prototype antenna, followed by rigorous performance evaluation using anechoic chamber and network analyser. Results demonstrate a significant enhancement in antenna gain, with the designed antenna exhibiting an analog gain of 11.15 dB at the specified frequency of 5.8 GHz, alongside an appreciable impedance bandwidth of 16 MHz.

Wideband Dual Circularly Polarized Substrate-Integrated Cavity Antenna Array for Millimeter-Wave Applications

Wideband Dual Circularly Polarized Substrate-Integrated Cavity Antenna Array for Millimeter-Wave Applications

Textile Bandwidth-Enhanced Half-Mode Substrate-Integrated Cavity Antenna Based on Embroidered Shorting Vias.

A textile bandwidth-enhanced half-mode substrate-integrated cavity (HMSIC) antenna based on embroidered shorting vias is designed. Based on the simulated results of the basic HMSIC antenna, two embroidered hollow posts with square cross-sections are added as shorting vias at the intersections of the zero-E traces of the TM210HM and TM020HM modes to shift the TM010HM-mode band to merge with the bands of the higher-order modes for bandwidth enhancement. A prototype is practically fabricated based on computerized embroidery techniques. Measurement results show that the prototype is of an expanded -10 dB impedance band of 4.87~6.17 GHz (23.5% fractional bandwidth), which fully covers the 5 GHz wireless local area network (WLAN) band. The simulated radiation efficiency and maximum gain of the proposed antenna are above 97% and 7.6 dBi, respectively. Furthermore, simulations and measurements prove its robust frequency response characteristic in the proximity of the human tissues or in bending conditions, and the simulations of the specific absorption rate (SAR) prove its electromagnetic safety on the human body.

The Leaky-Wave Perspective for Array-Fed Fabry–Perot Cavity and Bull’s-Eye Antennas

Two-dimensional leaky-wave antennas (LWAs) are a class of planar, traveling-wave radiators with attractive features of a low profile, ease of feeding, frequency reconfigurability of the radiation pattern, and polarization agility. Their use in conjunction with array feeders has been the subject of various investigations in recent decades, thanks to the additional degrees of freedom provided by the presence of multiple independent sources. Here, we provide a review of some of the most recent and promising array-fed two-dimensional (2-D) LWAs, selecting a couple of the most significant structures in application, namely Fabry–Perot cavity antennas and bull’s-eye antennas, and discussing some of their recently proposed advanced features.

A low-profile 3-D printable metastructure for performance improvement of aperture antennas

In order to increase the radiation performance of aperture-type antennas, this paper demonstrates a low-profile, planar, single-layer, three-dimensional (3-D) printable metastructure. The proposed hybridized metastructure is highly transparent as it is made out of novel hybrid meta-atoms having transmission coefficient magnitudes greater than – 0.72 dB and fully complies with the near-field phase transformation principle. The hybridized design approach makes the metastructure planar, low-profile, light in weight, and compatible with additive printing technology. For the proof-of-concept, such metastructure is developed and numerically verified to enhance the radiation performance of a resonant cavity antenna (RCA). With the proposed metastructure, the peak directivity of the RCA is improved by 8.6 dBi (from 11.4 dBi to 20 dBi) at the operating frequency of 12.4 GHz. The aperture efficiency and 3-dB directivity bandwidth of the RCA with the metastructure are 41.46% and 16.5%, respectively. Using readily accessible thermoplastics or polymers and copper with cost-effective fused deposition modeling (FDM) 3-D printing technology, the proposed planar hybridized metastructure can be prototyped commercially.

A High-Gain Millimeter-Wave Fabry–Perot Cavity Antenna With Phase Correction on a Meta-Ground Reflective Surface

A High-Gain Millimeter-Wave Fabry–Perot Cavity Antenna With Phase Correction on a Meta-Ground Reflective Surface

A tri-band low-profile shared-aperture mesh patch/Fabry-Perot cavity antenna

ABSTRACT A tri-band low-profile shared-aperture antenna is proposed. Based on structural multiplexing, a mesh patch is proposed to function as part of the partial reflective surface (PRS) of the Fabry-Perot cavity antenna (FPCA) in the middle- and high-frequency bands, as well as to function as the radiator of the patch antenna in the low-frequency band. Thus, the FPCA and the mesh patch antenna share the same aperture. A dual-band PRS is proposed, which can adjust its reflection amplitude independently in two frequency bands. By introducing artificial magnetic conductor (AMC) grounding to compensate for the transmission phase of the middle-frequency band, the proposed antenna can realize dual-band FPC resonance in a single cavity while maintaining a low profile. To validate the design concept, an antenna prototype is fabricated and measured. Measured results show that the impedance bandwidths of the proposed antenna are 4.74% (1.03–1.08 GHz), 0.42% (4.79–4.81 GHz), and 3.83% (11.52–11.97 GHz). The peak gain is 7.85 dBi at 1.06 GHz, 12.47 dBi at 4.81 GHz, and 20.6 dBi at 11.7 GHz. The isolation between the three bands is better than 30 dB. The three operating bands of the proposed antenna have a high degree of independence and can be flexibly adjusted.

Design of a low-profile bi-directional radiated Fabry-Perot cavity antenna with independent forward and backward radiation based on metasurface technique.

This paper introduces a novel Fabry-Perot cavity (FPC) antenna design based on metasurface technique to achieve bi-directional radiation with independent forward and backward beam control capability and a low-profile configuration. Two pieces of partially reflective metasurface (PRMS) based on receiver-transmitter architecture with independent control of transmission and reflection phases are designed to serve as the upper and lower layers of the FPC antenna, respectively. By manipulating the transmission phase distribution of the two pieces of PRMS, designable independent multi-beam bi-directional radiation patterns can be achieved. For validation, two FPC antennas based on the proposed configuration are designed with different bi-directional radiation patterns. Proved by simulated results, Antenna 1 can achieve forward dual-beam and backward single-beam radiation simultaneously with a return loss of less than -10 dB at 10.4 GHz. The two beams of forward radiation point in the -45° and 35° directions, respectively, with gains of 7.42 dBi and 7.70 dBi. The gain of the single beam of backward radiation is 10.82 dBi. Antenna 2 can achieve a four-beam radiation pattern with both forward and backward dual beams. The beam directions of the four beams are -153°, -44°, 37°, and 146°, respectively. The gains in each direction are 5.45 dBi, 6.63 dBi, 5.97 dBi, and 5.22 dBi, respectively. The overall profile is 23.72 mm (0.81 λ) for both antennas. The prototype of Antenna 1 is fabricated and measured. The results are in good agreement with the simulated counterparts, which demonstrates the feasibility of the proposed design methodology.

Wideband and High-Gain Q-Band Substrate Integrated Cavity Antenna and Array

Wideband and High-Gain Q-Band Substrate Integrated Cavity Antenna and Array

Single-fed Ku/Ka dual-band aperture shared planar antenna array for satellite communication

This paper presents a single-fed Ku/Ka dual-band aperture-shared planar antenna array designed for satellite communication. The need to enhance data transmission speeds has driven the exploration of higher frequency bands, such as the Ku-band and Ka-band. Researchers have been investigating the design of multiband antennas to achieve space miniaturization and cost-effectiveness in these higher frequency bands. However, previous works faced challenges, including spatial efficiency limitations, complex radiator structures, band isolation issues, and increased complexity in the feeding network. To address the abovementioned challenges, this paper proposes a single-fed Ku/Ka dual-band shared-aperture planar antenna array. By combining a patch antenna for the Ku-band and a cavity antenna for the Ka-band, a simple and single-fed network is realized. The proposed antenna element is further extended to a linear array antenna and a sequentially rotated array antenna. The implemented sequentially rotated array antenna exhibited a measured impedance bandwidth of 17.4–19.7 GHz (12.4%) and 27.0–29.0 GHz (7.1%). Moreover, the proposed sequentially rotated array antenna demonstrated measured peak gains of 13.7 dBi for right-hand circular polarization in the Ku-band receiver and a measured peak gain of 15.6 dBi for left-hand circular polarization in the Ka-band transmitter, making it highly suitable for satellite communication.

A stable high-gain cavity-stacked antenna array with compact high-order mode fed for W-band applications

This paper presents a W-band stable high gain 2 × 2 cavity-backed slot antenna array fed by compact high-order mode substrate-integrated cavity (SIC) with substrate-integrated waveguide (SIW) technology. The antenna element incorporates a 2 × 2 subarray of cross-shaped slots, excited by a high-order mode (TE220) SIC, ensuring uniform amplitude and balanced phase to achieve stable high-gain and high efficiency. Moreover, an additional SIW cavity is stacked above the 2 × 2 cross-shaped slots, incorporating a rectangular slot etched on the surface of the SIW cavity for radiation to further enhance the gain. This novel architecture yields a gain enhancement of 2.6 dBi compared to the traditional unstacked SIW cavity antenna. A prototype antenna array, consisting of 2 × 2 radiation elements and a low-loss 1-to-4 SIW power divider integrated with waveguide (WG) to SIW transition, is designed and fabricated in standard PCB technology. The measured results exhibit a −10 dB impedance bandwidth range from 91 to 97 GHz, a peak gain of 18.5 dBi, and a peak aperture efficiency of up to 78 %.

A Small-Size, High-Gain, Radiation Pattern-Reconfigurable Fabry–Pérot Cavity Antenna for 5G Communication

A Small-Size, High-Gain, Radiation Pattern-Reconfigurable Fabry–Pérot Cavity Antenna for 5G Communication

Application of Machine Learning-Assisted Global Optimization for Improvement in Design and Performance of Open Resonant Cavity Antenna

Application of Machine Learning-Assisted Global Optimization for Improvement in Design and Performance of Open Resonant Cavity Antenna

Effects of cavity resonance and antenna resonance on mode transitions in helicon plasma

Mechanisms of cavity resonance and antenna resonance and their coupling effects on mode transitions in argon helicon plasma excited by a half-helical antenna (14 cm in length) were investigated in this paper. Cavity length was changed to distinguish the effects of cavity and antenna resonances in experiments. Plasma parameters under various discharge conditions, such as input power (0–2500 W), magnetic field (0–1000 G) and cavity length (10–42 cm) were measured. Characteristics of helicon discharges and mode transitions in cases of fixed and continuously changing cavity lengths were compared. The results show that multiple axial eigenmodes (at least five in the present work) were observed in both cases. In fixed-length cavities, the helicon discharge changes abruptly during mode transitions, while in changeable-length cavities, discharge features can change continuously (e.g. in a large range of density from 1.7 × 1012 to 1.3 × 1013 cm−3) without mode transition. Mode transitions also occur as the cavity length increases at fixed input power and magnetic field with periodical variations of plasma parameters. Cavity resonance plays a dominant role in the formation of standing helicon waves of eigenmodes and mode transitions, while antenna resonance significantly affects the transition from inductively coupled modes to helicon wave modes. Enhanced inter-coupling of cavity resonance and antenna resonance appears at specific axial wavelengths of eigenmodes. The threshold conditions for mode transitions were deduced and the overall transition path of wave modes and the corresponding density were predicted quantitatively, which shows that cavity resonance determines the transition path of wave modes, while antenna resonance gives the lower limit of the transition path. Characteristics of helicon discharge and mode transition are closely related to the axial wavenumber. Cavity and antenna resonances influence the helicon discharge and mode transition by determining the axial wavenumber of eigenmodes.

A high gain and high radiation efficiency optical transparent Fabry–Perot cavity antenna

AbstractThis letter proposes a novel high gain, high efficiency optically transparent Fabry–Perot Cavity antenna operating in millimetre‐wave. The antenna employs dual layers of transparent partially reflective surface and a transparent artificial magnetic conductor structure to enhance the gain and gain bandwidth. The reflection amplitude and phase have a low sensitivity to the sheet resistance of the transparent materials, which greatly reduce the requirement for the conductivity of transparent material and simplify the manufacturing process. The size of the antenna is 3.47λ0 × 3.47λ0 × 0.68λ0. A peak gain of 14.2 dBi, peak radiation efficiency of 67.1% and optical transparency of 81% are achieved.

Wideband Low-Profile Fabry-Perot Cavity Antenna with Metasurface

A novel Fabry-Perot cavity (FPC) antenna with metasurface is presented, which can achieve broad bandwidth and low profile. Traditional FPC antennas, with rectangular microstrip antennas as feeds, have limited impedance bandwidth and struggle to make a compromise in the gain bandwidth and maximum gain value. To obtain wide bandwidth, the FPC antenna proposed in this paper utilizes a feed antenna loaded with parasitic patches. To widen impedance bandwidth and gain bandwidth and reduce the profile, a positive phase gradient partially reflective surface (PRS) and an artificial magnetic conductor (AMC) are located above and below the feed antenna, respectively. The phase property of the PRS and AMC also brings in a more smooth gain value curve. To further increase gain values, four metal reflector plates are located around the proposed antenna. The overall dimension of the antenna is 2.5λ0×2.5λ0×0.25λ0 (λ0 is the free space wavelength at 7.5 GHz). Simulated results show that the resonant cavity antenna proposed in this letter exhibits an impedance bandwidth of 13.3% (7–8 GHz) and a 3 dB gain bandwidth of 14.3% (7.02–8.10 GHz). The maximum gain in the whole operating band is 14.5 dBi. The measured results are in good agreement with the simulated ones.

Axial Ratio Bandwidth Enhancement of DBDCP Fabry–Pérot Cavity Antenna for Vehicular MIMO Communications and Sensing

Axial Ratio Bandwidth Enhancement of DBDCP Fabry–Pérot Cavity Antenna for Vehicular MIMO Communications and Sensing

Terahertz Planar Cavity Antenna Based on Effective Medium for Wireless Communications

Terahertz Planar Cavity Antenna Based on Effective Medium for Wireless Communications

An efficient and accurate semi-analytical matching technique for waveguide-fed antennas

Several RF and microwave radiating devices, such as horn antennas, Fabry–Perot cavity antennas, and aperture-fed focusing devices, are excited through rectangular waveguides. The impedance matching of the overall system (from the waveguide feed to the radiating aperture) is a task of crucial importance that is often addressed by means of brute-force parameter-sweep full-wave analyses or blind optimization algorithms. In both cases, a significant amount of memory and time resources are required. For this purpose, we propose here a simple, yet effective solution, which only requires a single full-wave simulation and a semi-analytical procedure. The former is used to retrieve the antenna input impedance at the end of the waveguide port excitation. The semi-analytical procedure consists in a transmission-line equivalent circuit that models two waveguide discontinuities (namely two capacitive irises) within the waveguide section, whose position and geometric features are finely tuned to obtain a satisfactory impedance matching around the working frequency. The proposed method is shown to be effective in diverse and attractive application-oriented contexts, from the impedance matching of a Fabry–Perot cavity antenna to that of a wireless near-field link between two aperture-fed focusing devices. A remarkable agreement between full-wave simulations and numerical results is found in all cases. Thanks to its versatility, simplicity, and a rather low demand of computational resources, the proposed approach may become an essential tool for the effective design of waveguide-fed antennas.