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This paper presents a simple, low-profile rectangular microstrip patch antenna for applications in the 28 GHz band. A regular rectangular microstrip patch antenna is initially designed. The antenna is then modified to perfectly resonate at 28 GHz and improve antenna performance in terms of S 11 , radiation gain, and impedance bandwidth. The antenna is optimized using inset feed to enhance the matching between the radiating patch and the feeding line. Then, a rectangular slit on the front edge of the patch is inserted with altering the antenna's dimensions to reduce its size. The suggested antenna uses a Rogers RT/Duroid-5880 substrate with a dielectric constant of 2.2, a thickness of 0.508 mm, and a loss tangent of 0.0009. The final design is small, measuring 8 × 8.489 × 0.508 mm 3 (≈ 0.75λ × 0.79λ × 0.05λ), having a maximum S 11 value of - 45 dB and an impedance bandwidth of 1.43 GHz, extending from 27.28 GHz to 28.71 GHz. The radiation gain is nearly consistent over the operating band, with above 8 dBi is achieved. Besides, the proposed antenna achieves a radiation efficiency of about 99% across the band. HFSS is employed for the design, simulations, and optimizations, while CST is used to validate the HFSS simulation findings. The simulation results from both simulators indicate a high level of agreement. The pervasive impact of wireless communication technology on daily life is evident in the rising number of users connecting their devices to wireless networks, resulting in a surge in data traffic. The increasing demand for high-speed networks, fueled by this trend, has driven the widespread adoption of fifth-generation (5G) wireless communication technology. With the capability to achieve remarkably high data rates, 5G operates in the millimeter spectrum, characterized by high losses that limit signal propagation distances and coverage. In addressing these challenges, Microstrip Patch Antennas (MSPAs) stand out as an optimal solution for 5G networks, offering advantages like compactness, lightweight design, cost-effectiveness, and ease of construction. MSPAs, recognized for their physical robustness, prove suitable for small wireless devices and high-directional antenna arrays in base stations.

A new design of a multi-resonance small slot antenna with variable band-notched function for ultra-wideband (UWB) applications is proposed. The proposed slot antenna consists of a square radiating stub and a ground plane with a pair of L-shaped parasitic structures and an inverted T-shaped strip protruding inside the rectangular slit, which provides a wide usable fractional bandwidth of more than 135% (2.98–16.73 GHz), while showing the band rejection performance in the frequency band of 5.05–5.9 GHz to avoid any interference from wireless local area network systems. The designed antenna has a small size of 20 × 20 × 0.8 mm3. Simulated and experimental results obtained for this antenna show that it exhibits good radiation behaviour within the UWB frequency range.

This paper presents a rectangular-shaped printed monopole antenna with circular polarization for Wi-Fi (2.4–2.484 GHz) and WiMAX (3.3-3.7 GHz) bands. The antenna relies on asymmetric arrangement of the patch with respect to the microstrip feed, in order to generate circular polarization. Dual-band (Wi-Fi and WiMAX) operation is enabled by inserting a slit in the corner of the ground plane. Simulation results show a bandwidth increase of 15.9% (2.2–2.58 GHz) for Wi-Fi, and of 24.16% (3.13–3.99 GHz) for WiMAX applications. Furthermore, beamwidths at the axial ratio of 3 dB equal 48˚ and 51˚ for the x-z plane and y-z planes, respectively.

In this paper, a tapered slot antenna capable of ultra-wideband communication was designed. In the proposed antenna, rectangular slits were inserted to enhance the bandwidth and reduce the area of the antenna. The rectangular slit-inserted tapered slot antenna operated at a bandwidth of 8.45 GHz, and the bandwidth improved upon the basic tapered slot antenna by 4.72 GHz. The radiation pattern of the antenna was suitable for location recognition in a certain direction owing to an appropriate 3 dB beam width. The antenna gain was analyzed within the proposed bandwidth, and the highest gain characteristic at 7.55 dBi was exhibited at a 5-GHz band. The simulation and measurement results of the proposed tapered slot antenna were similar.

An analytic solution is introduced for the stress field developed in a circular finite disc weakened by a central slit of arbitrary ratio of its edges and slightly rounded corners. The disc is loaded by radial pressure applied along two finite arcs of its periphery, anti-symmetric with respect to the disc’s center. The motive of the study is to consider the stress field in a disc with a mechanically machined slit (finite distance between the two lips) in juxtaposition to the respective field in the same disc with a ‘mathematical’ crack (zero distance between lips), which is the configuration adopted in case the fracture toughness of brittle materials is determined according to the standardized cracked Brazilian-disc test. The solution is obtained using Muskhelishvili’s complex potentials’ technique adopting a suitable conformal mapping function found, also, in Savin’s milestone book. For the task to be accomplished, an auxiliary problem is first solved, namely, the infinite plate with a rectangular slit (in case the resultant force on the slit is zero and also the stresses and rotations at infinity are zero), by mapping conformally the area outside the slit onto the mathematical plane with a unit hole. The formulae obtained for the complex potentials permit the analytic exploration of the stress field along some loci of crucial practical importance. The influence of the slit’s width on the local stress amplification and also on the stress concentration around the crown of the slit is quantitatively described. In addition, the role of the load-application mode (compression along the slit’s longitudinal symmetry axis and tension normal to it) is explored. Results indicate that the two configurations are not equivalent in terms of the stress concentration factor. In addition, depending on the combination of the slit’s width and the load-application mode, the point where the normal stress along the slit’s boundary is maximized ‘oscillates’ between the central point of the slit’s short edge (intersection of the slit’s longitudinal axis with its perimeter) and the slit’s corners.

A compact triple band-notched printed monopole antenna for ultra-wideband (UWB) application is presented. By inserting two triangular-shaped notches in both sides of the ground plane of microstrip feed line, additional resonances are excited and the bandwidth is increased up to 160%. Three sharp notched frequency bands at 3.8 GHz, 5.5 GHz, and 7.5 GHz are achieved by embedding a pair of rectangularshaped slits in the ground plane and two pairs of modified bow-shaped slits in the patch. This novel monopole antenna has ultra-wide frequency bandwidth for input impedance, compact size (24 mm × 20 mm), low cost fabrication and Omnidirectional H-plane radiation pattern which makes it suitable for ultra-wideband applications. The measured results reveal that the presented triple band-notched monopole antenna is a promising candidate for UWB communication systems to avoid interference with WiMax band (3.3-3.7 GHz), some C-band (3.7-4.2 GHz), WLAN (5.15- 5.825 GHz) bands and some C-band satellite communication systems (7-8 GHz).

We investigated the statistical behaviors of semiflexible polymer chains, which were simultaneously subjected to force stretching and rectangular tube confinement. Based on the wormlike chain model and Odijk deflection theory, we derived a new deflection length, by using which new compact formulas were obtained for the confinement free energy and force–confinement–extension relations. These newly derived formulas were justified by numerical solutions of the eigenvalue problem associated with the Fokker–Planck governing equation and extensive Brownian dynamics simulations based on the so-called generalized bead-rod (GBR) model. We found that, compared to classical deflection theory, these new formulas were valid for a much more extended range of the confinement size/persistence length ratio and had no adjustable fitting parameters for sufficiently long semiflexible chains in the whole deflection regime.

To develop a safer bone-bonding device that promotes early osseointegration with cortical bone perforation, novel subperiosteal device geometries were proposed and evaluated for their ability to facilitate surrounding bone formation and enhance bone-bonding strength. This study used animal experiments and mechanical testing to assess the performance of these designs. The experimental device consisted of two main components: a rounded rectangular plate and a centrally positioned cylinder. To promote the recruitment of bone-marrow-derived factors, slits were incorporated into the cylinder, and a center hole was created directly above it. Four device variations, differing by the presence or absence of the slits and center hole, were fabricated and then subjected to tensile tests for mechanical property evaluation. In the animal experiments, the devices were bilaterally placed on rat tibiae, and after four weeks, bone-bonding strength tests were performed. Additionally, micro-computed tomography and histological analysis of undecalcified sections were conducted. All devices demonstrated early osseointegration, and geometric design differences, specifically the presence or absence of the slits and center hole, significantly affected the mechanical properties and bone induction. However, no significant differences in bone-bonding strength were detected. These findings suggest that the newly formed bone inside the slits and center hole contributes to the reinforcement of the device.

This paper presents a slotted design for ultra-wideband (UWB) antenna. Design of a rectangular UWB antenna covering the frequency range 3.1-10.6 GHz, to achieve notch characteristics in the bands at 3.1-8.4 GHz and 8.6-10.6 GHz. By changing the direction of distribution of current to apply this technique by inserting three C-shaped holes and two pairs of rectangular notches below the antenna. The simulation results reveal that the proposed structure is in good accord with the simulation results. The proposed UWB antenna size is (100x90x1.6 mm)3. This proposed design could provide a solution to eliminating bands that interfere in a UWB band depending on the aperture design. The simulated findings reveal that the UWB antenna operates in the 8.5 GHz center frequency range and rejects all frequency bands utilizing slits. This antenna design can provide a solution to remove UWB bands from 3.1-10.6 except for 8.5 GHz which only works. By using the notch, we got a large increase in the gain. makes to be a suitable candidate for X-band-UWB applications.

A compact design of ultra-wideband (UWB) antenna with dual band-notched characteristics based on split-ring resonators (SRR) are investigated in this paper. The wider impedance bandwidth (from 2.73 to 11.34 GHz) is obtained by using two symmetrical slits in the radiating patch and another slit in the partial ground plane. The dual band-notch rejection at WLAN and X-band downlink satellite communication system are obtained by inserting a modified U-strip on the radiating patch at 5.5 GHz and embedding a pair of rectangular SRRs on both sides of the microstrip feed line at 7.5 GHz, respectively. The proposed antenna is simulated and tested using CST MWS high frequency simulator and exhibits the advantages of compact size, simple design and each notched frequency band can be controlled independently by using the SRR geometrical parameters. Therefore, the parametric study is carried out to understand the mutual coupling between the dual band-notched elements. To validate simulation results of our design, a prototype is fabricated and good agreement is achieved between measurement and simulation. Furthermore, a radiation patterns, satisfactory gain, current distribution and VSWR result at the notched frequencies make the proposed antenna a suitable candidate for practical UWB applications.