Probe Feed Research Articles

The Causal Nexus Between Different Feed Networks and Defected Ground Structures in Multi-Port MIMO Antennas.

Multiple input multiple output (MIMO) antennas have recently received attention for improving wireless communication data rates in rich scattering environments. Despite this, the challenge of isolation persists prominently in compact MIMO-based electronics. Various techniques have recently emerged to address the isolation issues, among which the defected ground structure (DGS) stands out as a cost-effective solution. Additionally, selecting the appropriate feed mechanism is crucial for enhancing the key performance indicators of MIMO antennas. However, there has been minimal focus on how different feed methods impact the operation of MIMO antennas integrated with DGS. This paper begins with a comprehensive review of diverse antenna design, feeding strategies, and DGS architectures. Subsequently, the causal relationships between various feed networks and DGSs has been established through modeling, simulation, fabrication, and measurement of MIMO antennas operating within the sub-6 GHz spectrum. Particularly, dual elements of MIMO antennas grounded by a slotted complementary split ring resonator (SCSRR)-based DGS were excited using four standard feed methods: coaxial probe, microstrip line, proximity coupled, and aperture coupled feed. The influence of each feed network on the performance of MIMO antennas integrated with SCSRR-based DGSs has been thoroughly investigated and compared, leading to guidelines for feed network selection. The coaxial probe feed network provided improved isolation performance, ranging from 16.5 dB to 46 dB in experiments.The aperture and proximity-coupled feed network provided improvements in bandwidth of 38.7% and 15.6%, respectively. Furthermore, reasonable values for envelope correlation coefficient (ECC), diversity gain (DG), channel capacity loss (CCL), and mean effective gain (MEG) have been ascertained.

Design of dual-band filtering patch antenna based on SIR multimode resonator

Abstract With the development of the communication field, more and more communication devices need multiple single-frequency antennas to work simultaneously. However, using multiple single-frequency antennas results in larger sizes. The miniaturized and dual-band communication system has become a new development trend. This paper designs a dual-band filtering patch antenna based on a multimode resonator, which is cascaded. The filter resonator part adopts step impedance resonance for branch shunt design, which can flexibly control the center frequency of two frequency bands. The filtering antenna utilizes a dual-layer substrate structure and achieves an integrated design through coupling probe feeding. This reduces the horizontal dimensions and improves miniaturization. Multiple radiation nulls are introduced outside the two-passband, and roll-off characteristics are evident. In addition, this design realizes high selectivity in the operating band. The antenna has large gains of 1.71 dBi and 6.25 dBi. It has good filtering and radiation characteristics.

Design and feed two models for microstrip antenna in two different feed methods and compare their properties

In any wireless communication, the antenna plays a very important role. The need in this technology is to reduce the size of the antenna, weight, and cost with a low profile, high performance, and low return loss (RL), which is what researchers are striving for. This paper attempts to implement a rectangular microstrip patch antenna and analyze its performance for different types of feeding techniques. In this research, we designed two thin slice antennas fed in two different ways, using FR4 epoxy as an insulating substrate with a dielectric constant of 4.3. Copper was used as a conducting material for the radiating patch and the transmission line, with nearly similar geometrical dimensions. The first antenna has dimensions of (31x 26x1.6) m3 and the second antenna has dimensions of (30x27x1.6) m3. The first antenna operates with a coaxial probe feed technique and the second one operates with a microstrip line feed technique. The return loss for the first antenna we obtained is -26.0113dB with a standing wave voltage ratio of 1.1053 at a frequency of 3.59GHz, and -24.743GHz with a standing wave voltage ratio of 1.8908 at a frequency of 5.529GHz. The return loss for the second antenna is -27.468dB with a standing wave voltage ratio of 1.0884 at a frequency of 3.45GHz. The design, simulation, and inclusion of shapes and graphics for both antennas were done using the CST (Computer Simulation Tool) program

Circularly Polarized Modified Minkowski Metasurface-Based Hybrid Dielectric Resonator Antenna for 5G n79 Wireless Applications

This paper presents a circularly polarized hybrid cylindrical dielectric resonator antenna (HCDRA) over a modified Minkowski unit-cell-based metasurface for 5G n79 band (4.4–5 GHz) and IEEE 802.11n WLAN (5 GHz) applications. The location of the perturbed probe feed mechanism and the asymmetric nature of the metasurface are the factors that influence the circularly polarized (CP) radiation within the DR element. The magnitude of E-field distribution and parametric study of the antenna to obtain the optimized feed location are the pieces of evidence of CP radiation. The return loss (RL) and axial ratio (AR) bandwidths produced by the proposed antenna are 1.837 GHz and 750 MHz with a peak gain of 7.04 dBic. The gain obtained is more than 5 dBic across the offered bandwidth of the proposed antenna. The proposed antenna is fabricated and tested in an anechoic chamber for measured results, and these results closely match with the simulation results.

Early nasogastric and nasojejunal feeding in patients with predictors of severe acute pancreatitis: а randomized controlled trial

OBJECTIVE: Studying the influence of early nasogastric (NG) and nasojejunal (NJ) probe feeding in patients with predictors of severe acute pancreatitis on the course and outcome of the disease. MATERIALS AND METHODS: An open randomized controlled study was performed in Neftyanik Occupational Healthcare Facility ICU. 64 patients with predictors of severe acute pancreatitis (APACHE II > 8, CRP > 150 mg/l, SOFA > 2) randomized by the envelope method for early (the first 24 hrs.) nasogastic or nasojejunal feeding. The standard polymer feeding formula enriched with dietary fibers was administered during the first 5 (five) days taking into account its tolerability. Raw data were statistically processed using SPSS-26 software. RESULTS: Comparison of the NG (n = 33) vs. NJ (n = 31) groups produced the following results: the duration (days) of treatment in the hospital was 21 (12; 42) vs. 24 (11; 35), p = 0.715; in ICU — 4 (2; 20) vs. 4 (3; 13), p = 0.803; mechanical ventilation (MV) — 1 (1; 3) vs. 1 (1; 1), p = 0.124; mortality — OR 0.830 (95 % CI 0.201–3.422), p = 0.796; severity (moderately severe or severe) — OR 1.29 (95 % CI 0.483–3.448), p = 0.611; number of patients subjected to surgery during the first period of the disease — OR 0.774 (95 % CI 0.243–2.467), p = 0.665; and second period of the disease — OR 1.682 (95 % CI 0.623–4.546), p = 0.305. CONCLUSIONS: No difference has been found between the groups of patients with severe disease predictors, who received early nasogastric or nasojejunal tube feeding using standard polymer formula with dietary fibers during early acute pancreatitis, as regards duration of treatment in the hospital, in ICU, numbers of mechanically ventilated patients, patients operated during the first and second disease periods, disease severity or mortality.

Introduction of the orthogonal mode via the polarization conversion parasitic structure for the isolation enhancement of MIMO patch antennas

Abstract In this study, a high-isolation multiple-input multiple-output (MIMO) microstrip patch antenna (MPA), which utilizes an orthogonal mode cancellation method is proposed. This method employs TM10 and TM01 modes, which are simultaneously excited in the rectangular passive MPA. Initially, a rectangular decoupling structure featuring polarization rotation characteristics is designed. Further studies show that by loading the polarization conversion parasitic structure (PCPS), the electric field of the spatial coupling wave can be transformed from the x-polarized TM10 mode to the y-polarized TM01 mode. Therefore, TM10 and TM01 modes from the excited antenna and decoupling structure are concurrently coupled to the passive antenna, forming an evident weak-field region on the passive antenna. Placing the feeding probe of the passive MPA within the weak-field region prevents signal reception at the port. Consequently, this results in an extremely low mutual coupling of −49 dB at a resonant frequency of 5.8 GHz. Finally, a prototype of the proposed antenna is fabricated and tested, and the measured results closely match the simulated results. Additionally, it is observed that PCPS slightly influences the performance of the MIMO antenna.

Multiband circularly-polarized stacked elliptical patch antenna with eye-shaped slot for GNSS applications

Abstract This paper introduces a tri-band stacked elliptical patch antenna featuring a right-handed circular polarized, designed to operate at the L2, L5, and L1 Global Navigation Satellite System bands. Initially, an elliptic patch is constructed and fed by a probe feed to generate TM110 and TM210 modes at resonance frequencies calculated using Mathieu functions. The probe position is precisely adjusted to excite the quasi-orthogonal mode of TM110 to generate circularly polarized (CP) waves at the L2 and L5 bands. Subsequently, an eye-shaped aperture is engraved into the elliptical patch to enhance the axial ratio (AR) beamwidth in the L2 and L5 bands and stimulate the orthogonal mode of TM210 to produce CP waves at the L1 band. Lastly, a stacked partially elliptical parasitic element is placed beneath the upper slotted elliptical patch to enhance the orthogonality of TM210 surface current versions and thus improve the AR beamwidth at the L1 band. The proposed antenna shows low reflection coefficient values at 1.12–1.33 (L2/L5), and 1.5–1.66 GHz (L1). The AR beamwidths are 133/213∘, 167/163∘, and 36/103∘ at two orthogonal cutplanes at L5, L2, and L1 bands, respectively. The antenna also has decent gains of 6–6.9 dBic across the three bands.

Design of dual circular polarized stacked patch antenna for BeiDou navigation satellite systems

In this article, a design of two-layered, dual circular-polarization (CP) and dual-band path antenna is presented for BeiDou navigation satellite (BDS) system applications. A single 50-Ω Co-axial probe feeding arrangement is employed to achieve dual-band operation and it feeds both the antennas simultaneously. This mode introduces the CP radiation on both upper (RHCP) and lower (LHCP) operation bands. The impedance bandwidth is further widened by accommodating two semi-circular stubs on the top patch. The fabricated and experimentally validated prototype radiates at 1.82 and 3.45 GHz (center frequency). The upper and lower operating band exhibits right and left-handed CP radiations, which constructs dual-band operation. The fabricated prototype has a physical size of πr2 × 0.024 λg with an antenna profile of 2.38 mm (0.024 λg). The experimentally validated upper and lower bands impedance bandwidth with |S11| < −10 dB are 21.1% and 11.1%, respectively. The fabricated prototype is a good candidate to use in BDS applications. [Q2

Mitigating mutual coupling effects on circular polarization for improved bandwidth in MIMO systems: A novel approach

An improved mutual coupling compensation in circularly polarized (CP) multi-input multi-output (MIMO) dielectric resonator antenna (DRA) is presented in this paper. Using trimming approach, the mutual coupling (MC) between closely spaced DRA units at 0.3λ has been significantly reduced while axial ratio performance has been maintained. Mutual coupling reduction is obtained by trimming the DRA to ensure low mutual coupling below −20dB. The exclusive features of the proposed MIMO DRA include wide impedance matching bandwidth (BW), triple band circular polarization, and suppressed MC between the radiating elements. The impedance bandwidth matches perfectly with a triple band's 3 dB axial ratio (AR). It is designed with characteristic mode analysis with good agreement of the measurement that has been obtained. Using the probe feed method, the DRA and patch strip are coupled together to allow bandwidth widening of the pro-posed DRA. An impedance bandwidth of 34% at a lower frequency to around 2% at a higher frequency was achieved in all resonance frequencies. Thus, we refer to our newly designed DRA as a proposed method for effectively reducing the mutual coupling between DRAs. Additionally, the 3 dB AR bandwidth matched at 3.3 GHz, 4.6 GHz, and 6.3 GHz with a percentage of 11.66%, 3.04%, and 2.22% obtained at the three different frequencies. Note that the proposed DRA exhibits low mutual coupling (below −20 dB) at the targeted frequencies, which is suitable for better signal reception for MIMO applications. By computing, the metrics envelop correlation coefficient, diversity gain, channel capacity loss, and total active reflection coefficient, the MIMO performance of the proposed antenna is verified. The experiments show a close result between simulated and computed validation of the proposed DRA.

Substrate integrated waveguide cavity‐backed slot antenna with low cross‐polarization over the full bandwidth

AbstractHere, a single‐layered single‐fed slot antenna is realized with low cross‐polarization over the full operating bandwidth. This design consists of a circular‐shaped cavity resonator, employed by using substrate integrated waveguide (SIW) technique and a square‐ring slot on the upper metal cladding of the cavity. The antenna is fed using a probe feed which excites the design in dual mode, that is, slot mode and inset patch mode. Due to the proximity of these dual resonances, the antenna operates over a relatively wider bandwidth than previously suggested designs with the claim of low cross‐polarization. The proposed design helps to realize more than 35 dB of co‐to cross‐pol isolation in both E and H planes. Overall experimental results demonstrate a good radiation performance, it is confirming up to 15–20 dB improvement in cross‐polarization level with enhanced enhancement bandwidth which makes it appropriate for a modern wireless application.

Cylindrical conformation and miniaturization of cavity-backed magnetoelectric antenna with an outer Γ-shaped probe

Abstract In this article, the cylindrical conformation of a linearly polarized cavity-backed magnetoelectric (ME) antenna is studied. Starting from a planar ME antenna presenting a wide bandwidth due to a specific design of its feeding probe, the impact of conformation is shown; the coupling between the ME dipole and the cavity walls is demonstrated to be the key element to keep a wideband behavior. Conformal antennas offering the same impedance bandwidth as the planar antenna are presented operating at Global Navigation Satellite System frequencies (1.164–1.61 GHz). As a result of the conformation, the antenna size has to be reduced to maintain the coupling and a wideband behavior. A prototype conformed to a 44-mm radius cylinder was built using low-cost additive manufacturing. External dimensions of 62 × 62 × 35 mm3 (0.285 × 0.285 × 0.16λ03, where λ0 is the wavelength at 1.38 GHz) were obtained, showing a ground plane area reduction of 46% compared to the planar antenna with the same materials. The conformal antenna also exhibits very steady radiation properties with a gain of around 4.5 dBi and a very similar and stable 3 dB beamwidth around 113° in E- and H-planes. A relatively good agreement is found between measurements and simulation.

Smallest form-factor multi-stacked ceramic patch antenna on package for 5G millimeter-wave mobile applications

A new design for a 5G millimeter-wave array antenna that is only 2.8 mm wide, using multi-stacked high-temperature ceramic substrates, is proposed in this paper. The antenna is designed to meet the requirements for esthetically pleasing and ergonomic smartphone designs and efficient component installations. To overcome challenges posed by the high relative permittivity and dielectric loss tangent of the ceramic substrates, the authors use a polymer adhesion layer with an air cavity and U-shaped probe feeding structures. The resulting 1 × 5 ceramic array antenna has a −10 dB impedance bandwidth in the low-band range of 24.25–28.35 GHz and the high-band range of 37–40 GHz, which covers the 5G New Radio frequency ranges n258, n260, and n261.

ANALYSIS OF THE EFFECTIVENESS OF PATHOGENETIC PHARMACOTHERAPY FOR SPINAL MUSCULAR ATROPHY IN CHILDREN IN THE CHUVASH REPUBLIC

Since 2020, pathogenetic pharmacotherapy of spinal muscular atrophy in children has been introduced into use in the Chuvash Republic. To date, the results of more than two years of using Nusinersen and Risdiplam have been accumulated. The aim of the study was to generalize the experience of pathogenetic pharmacotherapy for spinal muscular atrophy with an assessment of the factors determining its effectiveness in children in the Chuvash Republic. Materials and methods. A retrospective analysis of medical records of 15 inpatient patients with spinal muscular atrophy who were treated in the settings of the neuropsychiatric department of the Republican Children's Clinical Hospital under the Health Ministry of Chuvashia for the period from 2020 to May 2023 was carried out. The effectiveness of therapy was evaluated using clinical scales for assessing motor functions recommended for patients with spinal muscular atrophy. Study results. In the group of patients with severe manifestations (type I spinal muscular atrophy), clinical improvements in motor functions during treatment were observed in 50%, there was no positive dynamics in 30%, deterioration was registered in 20%. Attention should be paid to the fact that at the early start of therapy (up to 6 months after the disease manifestation), at least a slight increase in motor functions was observed in 100% of patients. On the other hand, the effectiveness of Nusinersen and/ or Risdiplam was observed in none of the patients with type I or II spinal muscular atrophy at late therapy, but these patients also repeatedly observed deterioration of motor functions. During the period of observing the children, even when the facts of improvement in motor function in points were established, swallowing disorders and respiratory failure often progressed, which required probe feeding and continued artificial pulmonary ventilation. At this, no facts of developing undesirable adverse reactions to medications were noted. Conclusions. The analysis of pharmacotherapy with Nusinersen and Risdiplam in children with spinal muscular atrophy in the Chuvash Republic indicates a better effect of pathogenetic therapy at its early onset and a lower initial severity of the disease. It should be noted that there was no significant improvement in the quality of life in any of the cases. In addition, in order to effectively use these drugs, objective methods should be developed to assess the survival of motor neurons and the quality of life, as well as to recommend the timing of pathogenetic therapy initiation.

A Novel High-Isolation Dual-Polarized Patch Antenna with Two In-Band Transmission Zeros.

In this study, we present a novel dual-polarized patch antenna that exhibits high isolation and two in-band transmission zeros (TZs). The design consists of a suspended metal patch, two feeding probes connected to an internal neutralization line (I-NL), and a T-shaped decoupling network (T-DN). The I-NL is responsible for generating the first TZ, and its decoupling principles are explained through an equivalent circuit model. Rigorous design formulas are also derived to aid in the construction of the feeding structure. The T-DN realizes the second TZ, resulting in further improvement of the decoupling bandwidth. Simulation and experimental results show that the proposed antenna has a wide operating bandwidth (2.5-2.7 GHz), high port isolation (>30 dB), and excellent efficiency (>85%).

All‐dielectric circularly polarised loop antenna made of high‐permittivity ceramic/water

AbstractA kind of all‐dielectric circularly polarised (CP) loop antenna made of high‐permittivity material is proposed. The leaky‐wave radiation from a high‐permittivity dielectric waveguide is utilised here to support the operation of the proposed antenna. A non‐closed dielectric loop covering a three‐quarter circle is adopted to generate CP radiation and it is connected with the dielectric ground via one of bending ends to form an all‐in‐one structure of the antenna. The other end is also bent and vertical to the ground, but hanging in the air for probe feed. As two kinds of typical high‐permittivity dielectric materials, zirconia ceramic and pure water are used to implement the proposed design respectively. On one hand, an all‐ceramic CP loop antenna made of zirconia is proposed. And benefiting from the low loss and high melting point of zirconia, the proposed ceramic antenna has superiority in radiation efficiency and could adapt to a harsh environment. On the other hand, by using pure water and transparent container, a fully‐transparent CP water loop antenna can be obtained. Finally, a 3‐D printing technology is adopted in the manufacturing of ceramic structure and resin container. Measured results of both antennas demonstrate the validity of the proposed design.

A 2-D Beam Scanning Array Antenna Fed by a Compact 16-Way 2-D Beamforming Network in Broadside Coupled Stripline

A 2-D beam scanning array antenna fed by a compact 16-way 2-D beamforming network (BFN) designed in Broadside Coupled Stripline (BCS) is addressed. The proposed 16-way 2-D BFN is formed by interconnecting two groups of 4x4 Butler Matrix (BM). Each group is composed of four compact 4x4 BMs. The critical point of the design is to propose a simple and compact 4x4 BM without crossover in BCS to achieve a better transmission coefficient of the 16-way 2-D BFN with reduced size of merely 0.8λ0 × 0.8λ0 × 0.04λ0. Moreover, the complexity of the interface connection between the 2-D BFN and the 4x4 patch array antenna is reduced by using probe feeding. The 16-way 2-D BFN is able to produce the phase shift of ±45°, and ±135° in x- and y- directions. The 2-D BFN is easily integrated under the 4x4 patch array to form a 2-D phased array capable of switching 16 beams in both elevation and azimuth directions. The area of the proposed 2-D beam scanning array antenna module has been significantly reduced to 2λ0 × 2λ0 × 0.04λ0. A prototype operating in the frequency range of 4-6GHz is fabricated and measured to validate the concept. The measurement results agree well with the simulations.

Palaeoecological deductions from osteohistology.

Palaeoecological deductions are vital for understanding the evolution and diversification of species within prehistoric environments. This review highlights the multitude of ways in which the microanatomy and microscopic structure of bones enables palaeoecological deductions. The occurrence of growth marks in bones is discussed, and their usefulness in deducing the ontogenetic status and age of individuals is considered, as well as how such marks in bones permit the assessment of the growth dynamics of individuals and species. Here osteohistology is shown to provide insight into the structure of past populations, as well as ecological relationships between individuals. In addition, the response of bones to trauma, disease and moulting is considered. Finally, I explore how osteohistology can give insight into ecomorphological adaptations, such as filter feeding, probe feeding and saltatorial locomotion. Methodological advances in three-dimensional microtomography and synchrotron scanning bodes well for future studies in osteohistology and despite some compromises in terms of tissue identity, circumvents the crucial issue of destructive analyses.

Metamaterial-Based Low-Profile Broadband In-Band Full-Duplex Antenna

A low-profile wideband antenna with extremely high isolation is proposed for in-band full-duplex applications. It is designed in a coplanar structure with a periodic array of non-uniform metamaterial cells, a hook-like feeding probe, and four mushroom-like structures. The non-uniform metamaterial cells are excited by a hook-like feeding probe to achieve horizontal polarization. Meanwhile, two slots at the end of the ground are coupled with microstrip feed lines for vertical polarization. As a result, leakage currents between two symmetrical feed structures are suppressed to realize high isolation in wide operation bandwidth. Furthermore, four mushroom-like structures are embedded in the corners of the metamaterial cells to improve bandwidth and isolation. Measured results demonstrate that the proposed antenna with a low profile of 0.06 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the wavelength at the center frequency of the operating band) achieves a -10 dB impedance bandwidth of 24.5% from 3.20 GHz to 4.09 GHz and a high Rx/Tx isolation of more than 50 dB. The proposed design has the merits of low profile, wideband, high isolation, and simple feeding structure, which makes it a competitive candidate for in-band full-duplex applications.

High-Gain Dual-Band Aperture-Shared CP Patch Antenna With Wide AR Beamwidth for Satellite Navigation System

This paper presents a compact dual-band, high-gain, light-weight, circularly polarized (CP) microstrip patch antenna with wide axial ratio (AR) beamwidth for multiple satellite communication, positioning and navigation systems The antenna consists of a main dual-frequency coplanar metal frame radiator, a circular metal capacity-loaded radiator, and some coaxial feeding probes. Due to the use of air dielectric, the maximum right-hand circularly polarized gain of the antenna is up to 6.2 dBic in the lower bands and 6.3 dBic in the upper bands. By utilization of dual-frequency coplanar patch and metal capacity-loaded technology, the dimensions of the aperture-shared CP antenna are only 0.38 λ × 0.38 λ × 0.04 λ. To increase the 3-dB AR beamwidth, a novel vertically grounded shorting sheet is introduced. The 3-dB AR beamwidth ranges from −120° to 100° at 1.227 GHz and from −90° to 95° at 1.575 GHz. As a result, the proposed antenna is an excellent candidate for high gain, wide AR beamwidth and compact air dielectric antenna.

Self‐decoupling coupled‐fed patch antennas for 5G multiple‐input multiple‐output applications

AbstractSelf‐decoupling coupled‐fed patch antennas are designed in this letter. The self‐decoupling mechanism is based on the weak‐field region formed by the T‐shaped probe feed and the radiating patch of the antenna element itself. When another identical antenna element is placed in the weak‐field region, high isolation between the two elements can be achieved without adding extra decoupling structures. To validate the decoupling mechanism, a dual‐element antenna array is initially built and an isolation level of better than 30 dB is achieved over the impedance band of 3.3–3.66 GHz with an element spacing of 0.53λ0. Next, a four‐element multiple‐input multiple‐output (MIMO) linear antenna array is presented to further verify the decoupling method and good isolation performance is also obtained, which demonstrates that the proposed designs are good candidates for 5G MIMO applications.