Transverse Slots Research Articles

Comparison of simplex and duplex drum brakes linings with transverse slots in vehicles

In this paper, experimental comparison between Simplex and Duplex drum brake units performance for three different drum lining profile designs is carried out. The three linings profiles are normal (no slot), with one slot and with three slots. In this study, brake test rig has been designed to represent the actual braking process environment. Brake oil pressure and drum speed are the operational parameters that are varied during the experimental work. From the experimental work and mathematical models for brake force, brake factor, and final friction temperature, the comparisons were carried out. The final conclusions indicate that lining with one slot profile is the most suitable, since the percentage improvement of mean brake force and brake factor of duplex drum brake (D) linings versus simplex drum brake (S) linings reaching 84.09% and 82.73% higher than three slots lining profile but lower than lining with normal profile at low pressure 5 bar and low speed 50 rpm. Also, the percentage improvement of mean primary shoe final friction temperature reduction for the one slot profile reaches 30.00% higher than normal lining profile but lower than lining with three slots profile at high pressure 20 bar and drum speed 50 rpm.

Leaky wave antenna loaded complementary elements with dual-stopband suppression

In this paper, a periodic leaky wave antenna (PLWA) using complementary elements is proposed. The complementary elements of the transverse slot (horizontal magnetic current) and the monopole pairs (vertical electric current) in the substrate integrated waveguide (SIW) is employed as the radiation element, which can simultaneously suppress closed stopband β 0 p = π and open stopband (OSB) β −1 p = 0 to enhance the forward scanning of the LWA. Additionally, the gain and cross-polarization of the element are improved due to the loading of the monopole pairs. The LWA achieves forward and backward scanning from −73° to 10° when operating at the n = −1 spatial harmonic (SH), with corresponding gains of 11.5 to 15.4 dBi. When operating at the n = 0 SH, it achieves forward scanning from 58° to 72°, with corresponding gains of 5.2 to 7.5 dBi. Moreovere, due to the element and its symmetrical structure, the cross-polarization within the entire operating frequency range is less than −35 dB. The design concept is validated through processed, fabricated, and tested.

Compact metal‐printed filtering antenna with wideband performance

AbstractIn this letter, a wideband cavity‐backed filtering antenna based on 3‐D printing technology is proposed for millimeter wave applications. This antenna is made up of an air‐filled metal cavity, attached with two transverse slots on its upper surface. By exciting one TE110 cavity mode and two slot modes simultaneously, wideband performance can be obtained. Besides, by properly bending one slot into U‐shape, two radiation nulls appear at two sides of the passband, yet causing the increase of the cross‐polarization in H‐plane. To remedy this, the U‐shaped slot is further bent at its ends, successfully suppressing the cross‐polarization by 7 dB. The final proposed filtering antenna is implemented and measured, showing a wide bandwidth of 37.3%, covering from 21.4 to 31.2 GHz. And the measured maximum gain is 6.6 dBi in band, with two radiation nulls at 14.6 and 40 GHz.

A segmented periodic slot array leaky‐wave antenna for beamforming applications

AbstractA segmented periodic slot array leaky‐wave antenna (LWA) is proposed for beamforming applications. The LWA consists of segments, each with a unique propagation constant achieved through varying periodicity and slot size. By using segments with different propagation constants, the proposed LWA can achieve beamforming such as flat‐top beams and side‐lobe level (SLL) reduction. The LWA is based on a substrate‐integrated waveguide with periodic double transverse slots in the broad wall of the waveguide. The double slots allow for reflection‐canceling to suppress the broadside stopband and hence can achieve beamforming capabilities in the backward, broadside, and forward directions. Full‐wave simulations are used to demonstrate the proposed concept for flat‐top beamforming in the mm‐wave band at 30 GHz. Experimental demonstration is conducted using two prototypes for flat‐top beams and SLL reduction, with good agreement with full‐wave simulations.

Design and Analysis of Novel Microstrip-Based Dual-Band Compact Terahertz Antenna for Bioinformatics and Healthcare Applications

This paper presents a compact microstrip-based dual-band antenna for terahertz (THz) technology, catering to the increasing demand for high-frequency, high-gain, and wideband THz antennas. THz technology has numerous applications, including its demands in bioinformatics and healthcare. To address this need, the proposed antenna operates in two frequency bands: 3.6 THz to 4.3 THz and 5 THz to 5.7 THz, enabling its use in THz band communication. The antenna design features a microstrip patch with two transverse slots and one longitudinal slot as a radiator, fed with a microstrip line. The transverse slots enable dual-band resonance, while the longitudinal slots enhance bandwidth and efficiency. Using a 10µm thick polyamide material with a dielectric constant of 3.55, the antenna achieves a compact size of 40 × 40 µm2, lightweight construction, high radiation efficiency, and a wide impedance bandwidth. Simulation results confirm good impedance matching characteristics, with minimal voltage standing wave ratio and return loss of -10dB or less. The antenna exhibits an impedance bandwidth of -10dB at 700 GHz, a peak radiation efficiency of 85%, a peak gain of 7.86 dB, and an omnidirectional radiation pattern. These favorable attributes position the proposed antenna as an excellent choice for various THz applications, particularly in bioinformatics and healthcare applications.

Optical trapping based on microring resonators with a transverse slot structure.

Over the past few decades, optical manipulation has emerged as a highly successful tool in various fields such as biology, micro/nanorobotics, and physics. Among the different techniques, the transverse slot optical waveguide has shown remarkable potential in enhancing the field and significantly improving optical trapping capabilities. Additionally, microring resonators have demonstrated the ability to enhance the field at specific resonance wavelengths, enabling the manipulation and capture of particles. In this study, we investigated the impact of the structure on nanoparticle capture by introducing a 50nm transverse slot in a 5µm microring resonator. Through the integration of a transverse slot in the microring resonator, we observed a substantial increase in the maximum bound optical power for a nanosphere with a refractive index of 1.6 and a diameter of 50nm, reaching 3988.8pN/W. This value is 2292 times higher than the maximum optical force in a straight waveguide and 2.266 times higher than the maximum optical force in a microring resonator. The proposed structure significantly enhances the optical trapping capabilities for nanoscale particles, thus paving the way for the development of advanced micro/nanomanipulation techniques.

Experimental and numerical analysis on electrolytic bubble group dynamics in the aluminum electrolysis process using the slotted anode

The CuSO4 aqueous solution electrolysis experiment is conducted to investigate the electrical bubble dynamics using the slotted anode to reveal the gas removal mechanism. A three-dimensional transient mathematical model coupled discrete phase model (DPM) − discrete-continuum transition model (DCTM) − volume of fluid (VOF) method is developed to track the dispersed bubble trajectory, bridge the dispersed bubble to continuous gas, and resolve the deformed bubble surface, respectively. The slotted anode decreases the bubble diameter compared with the traditional anode because the slot shortens the bubble motion distance to decrease the bubble residence time. The slot width smaller than the detached bubble diameter can limit the bubble deformation. Increasing current plays a dual role in bubble motion in the experiment: it accelerates the bubble coalescence process but decreases the bubble collision probability. The longitudinal slot is more conducive to reducing the maximum bubble coverage and increasing the bubble release frequency than the transverse slot.

A novel reconfigurable H-plane Horn leaky wave Substrate Integrated Waveguide MIMO antenna for K band

In this paper a novel reconfigurable H-plane horn Multiple Input Multiple Output (MIMO) leaky wave substrate integrated waveguide (SIW) antenna is proposed. The antenna is operating at two resonant frequencies, 22.8 GHz and 26.32 GHz. The transverse periodic leaky wave slots are radiating power in the broadside direction at 22.8 GHz and pattern diversity is achieved at 26.32 GHz. Dielectric loading and an array of meta-material structures are used, which further improve gain of the antenna. The antenna achieves better matching with a return loss of –33.5 dB at 22.8 GHz and maximum isolation of −38.7 dB at 26.32 GHz is achieved between antenna elements. A 2x2 and 4x4 MIMO SIW antenna is designed and analyzed in this paper. All the MIMO performance measurement parameters have values within limits. The antenna achieves a maximum gain of 7.3 dBi and 8.1 dBi. The proposed antenna operates in the K band (18 GHz–27 GHz) region, making it suitable for automotive radars and short-range applications.

Millimeter-Wave Conformal Directional Leaky-Wave Antenna Based on Substrate-Integrated Waveguide

Conformal antennas have been widely used in many fields due to their advantages of low air resistance and better visual appearance. In this paper, an arced conformal leaky-wave antenna (LWA) for a designable directional beam is proposed. The antenna is achieved based on a substrate-integrated waveguide (SIW). On the upper surface, a series of non-uniform transverse slots are etched. In order to guide the design of the antenna, as another key contribution of this work, a theoretical model for the traveling-wave structure is established. Using the model, the radiation property of the LWA is analyzed. In addition, by inputting the desired beam direction, the structural parameters of the LWA can be generated through the model. To verify the performance of the antenna and the model, an LWA prototype working at 28 GHz was fabricated and tested in a microwave anechoic chamber. The experimental results are in good agreement with the simulation results. The antenna achieved a gain of 9.96 dBi with cambered surface area of 1.89 λ02. The proposed method may be a promising candidate for conformal wireless communication applications.

Active control of pressure fluctuations in an incompressible turbulent cavity flow

Large-eddy simulations of incompressible turbulent boundary layer flows over an open cavity are conducted to investigate the effects of wall-normal steady blowing on the suppression of pressure fluctuations on the cavity walls. The length (L) to depth (D) ratio (L/D) of the cavity is 2 and the Reynolds number based on the cavity depth (ReD) is 12,000. Wall-normal steady blowing is imposed through a limited transverse slot in an upstream region of the cavity leading edge while varying the momentum coefficient (Cμ). As the value of Cμ increases, the pressure fluctuations on the cavity walls decrease mostly due to weakened impingement of turbulent vortical structures residing in the shear layer on the aft wall by lifting effects, reaching a maximum reduction of −7.61% compared to a baseline when Cμ=0.015. However, as the value of Cμ increases further, the pressure fluctuations increase gradually, exceeding that of a baseline when Cμ>0.05. Because intensified turbulent vortical structures in the shear layer with an increase of Cμ lead to strong interactions of small-scale vortices with the cavity walls with an accompanying large motion of the primary recirculation zone within the cavity, additional pressure fluctuations generated on the cavity walls deteriorate the control performance due to the blowing.

Miniaturization of ultra‐wideband Vivaldi antenna by utilizing double‐layer structure with slots

AbstractIn a Vivaldi antenna, a symmetrical double‐sided structure is introduced to reduce the lower‐side frequency. Multiple transverse and longitudinal slots loaded into the redundant conductor layer of the Vivaldi structure can stimulate resonant modes at the higher frequency end, further broadening the antenna bandwidth towards high frequencies. Meanwhile, impedance matching slots are introduced into the conductor layer on the feed side to achieve ultra‐wideband (UWB) antenna. The overall size of the final antenna is 23.5 mm × 30.0 mm × 2.4 mm, while the relative bandwidth (S11 < –10 dB) reaches 142% (2.49–14.78 GHz). This miniaturized UWB antenna has similar directional patterns in the operating band, with an average gain of 4.82 dB.

Design of Leaky-Wave Antenna With Wide-Angle Backfire-to-Forward Beam Scanning Based on Generalized Pattern Synthesis

Frequency-scanning antenna has been extensively explored in radar and vehicle communication systems, but it is a challenge to provide methodological guidance to achieve a wide scanning angle. Here, a generalized pattern synthesis method is proposed and a leaky-wave antenna with wide scanning range is designed to verify the technique. First, a generalized antenna element (GAE) is presented, whose main beam can steer continuously with frequency. Meanwhile, the phase constant of the leaky wave determines the beam direction of the array factor. Then, a leaky-wave antenna can steer with a large beam scanning angle and stable gain as patterns of the array factor and the GAE are manipulated simultaneously. To verify, a prototype SIW LWA with double-layer transverse slots is fabricated and measured. Experimental results show this antenna achieves continuous dual-beam scanning from backfire (-90∘) to forward (±20∘) from 12.4 GHz to 19.9 GHz with a total coverage range of 220∘ and the realized gain varying from 8.3 dBi to 12.8 dBi.

Broad Stopband, Low-Loss, and Ultra-Compact Dual-Mode Bandpass Filter Based on HMSIRC

In this investigation, an ultra-compact dual-mode bandpass filter (BPF) with a wide stopband response is realized by using a half-mode substrate-integrated rectangular cavity (HMSIRC). The HMSIRC resonator is designed with a cavity that is rectangular in shape and has metallic vias along three of the sides. The fourth side is open-ended and contains microstrip feed lines. For the purpose of constructing a magnetic wall, a rectangular slot is cut into each of the HMSIRC’s three edges. In order to produce an electrical wall that may generate a variety of resonances, the side with the open edges is provided with a single metallic via in the center. After that, a second-order BPF is generated by loading a transverse slot in the middle of the BPF, which enables independent frequency regulation of the mode frequencies. The eigen-mode analysis; field distributions; coupling matrix; and full-wave simulation of the proposed HMSIRC filter topology are used to develop the working principle of the filter. A second-order BPF is realized, constructed, and experimentally validated in order to provide evidence that the theory is correct. The BPF prototype achieves satisfactory performance thanks to its compact footprint of 0.028 λg2; its broad passband of 15.9%; its low insertion loss of 0.41 dB; and its wide stopband of 4.36 f0 with a rejection level greater than 20 dB. Both the measured and EM-simulated responses of the BPF are very consistent with one another.

A Circular-Polarization-Reconfigurable Holographic Leaky-Wave Antenna With Fixed-Frequency Beam-Scanning Property

A fixed-frequency beam-scanning leaky-wave antenna (LWA) with circular-polarization (CP) reconfigurable property operating in Ka band is developed in this letter. A groove gap waveguide (GGW) structure is adopted for feeding and transmission, and 64 CP patches are excited through the cross-shaped slots etched over the GGW. By switching the conditions between “ON” and “OFF” of the PIN diodes, these exciting slots can act as either transverse slots or longitudinal slots, and hence to realize the transition between left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP). Meanwhile, the fixed-frequency beam-scanning characteristic is achieved by manipulating the hologram, which is controlled by the activation states of diodes. Finally, the presented fabrication is taken into experiment to verify its performance, and an agreement can be observed in the simulated and experimental results. The eventual peak gains reach 13.4 dBic in the LHCP state and 12.1 dBic in the RHCP state, respectively. In addition, a beam-scanning range up to 100° between -50° and 50°is realized with desirable CP reconfigurable performance between LHCP and RHCP.

A Circular-Polarized Vortex Beams Generation With Orbital Angular Momentum Based on a Leaky-Wave Antenna

A circular-polarized vortex beams generation with orbital angular momentum (OAM) based on a leaky-wave antenna with substrate integrated waveguide (SIW) is proposed in this letter. The loop leaky-wave antenna is designed to transmit vortex beams with various OAM modes controlled by the operating frequency. With the frequency change from 11GHz to 12GHz, the OAM modes change accordingly. The OAM antenna realizes a low profile by use of the leaky-wave structure. Meanwhile, two transverse slots and one longitudinal slot are utilized to realize circular polarization to improve the mode purity of OAM. Notably, the measured results demonstrate that the gain reaches 7.18 dBi with vortex beams generated by four OAM modes (+2, +1, 0, -1). And the axial ratio (AR) is good from 11GHz to 12GHz, indicating that circular polarization is achieved.

D-Band Air-Filled Substrate Integrated Waveguide (AFSIW) and Broadband Stripline to AFSIW Launcher Embedded in Multi-Layer PCBs

We report <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$</tex-math> </inline-formula> -band air-filled substrate integrated waveguides (AFSIWs) with solid copper sidewalls fabricated inside a multi-layer printed circuit board (PCB) with broad wall width of 1.6 mm and cavity height of 300 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m. Measurements show a loss of 0.07–0.08 dB/mm across 115–155 GHz. This result is the first demonstration of an AFSIW above 100 GHz in a low-cost mass manufacturable PCB and has the lowest loss compared to reported planar PCB lines or substrate integrated waveguides (SIWs) in PCBs and Interposers. We also introduce a broadband stripline to the AFSIW launcher using a broad wall transverse slot which offers ease of manufacturability over existing transitions having a measured insertion loss of 1.1 dB and 27% bandwidth. The combination of a low-loss AFSIW and wideband launcher allows both striplines and AFSIWs to coexist in the same multi-layer PCB.

A dual‐band dual‐polarized shared‐aperture SIW slot antenna array with beam scanning

AbstractThis letter proposes a low‐profile dual‐band dual‐polarized (DBDP) substrate‐integrated waveguide (SIW) slot antenna array with beam scanning. By stacking the SIW transverse slot array (TSA) above the longitudinal slot array (LSA) in one aperture, two orthogonal polarizations are generated at two bands. To avoid the radiation slots of the LSA and the TSA from overlapping, the LSA is developed based on the proposed LSA unit whose collinear‐slot arrangement is realized by introducing metallized vias. Two planar parabolic reflectors based linear source generators (LSGs) are integrated to feed the shared‐aperture radiation array. By moving two independent SIW horns, the proposed antenna can obtain the steering angles of ±34° and ±27° at the central frequencies of 11.2 and 13 GHz, respectively. Two beams with orthogonal polarizations scan in the same plane. The simulated results have been validated by the experimental ones. The proposed antenna has low profile and is a potential candidate for satellite and wireless communications.

SIW Leaky Wave Antenna for THz Applications

This paper proposes a new design of leaky wave antenna (LWA) based on substrate integrated waveguide (SIW) technology for THz applications. The suggested LWA structure has a combination of longitudinal and transverse slots and makes a 10-element linear array of radiating elements. To address the problem of open-stop-band (OSB), four additional smaller slots were etched on the corners of longitudinal and transversal slots. At the broadside, this LWA provided a gain of 12.33 dBi, and a continuous wide beam scanning range from +78° to −6° via the broadside while exhibiting efficient radiation performance over the operating frequency bands of 105 GHz to 109 GHz with a peak gain of 16.02 dBi.

Miniaturized and optimized half mode SIW bandpass filter design integrating Hilbert cells as DGS

ABSTRACT This paper demonstrates a novel configuration of half mode substrate integrated waveguide HMSIW bandpass selective filter based on Hilbert cells as DGS. Two 50-Ohm conventional micro-strip are used as feed lines. The filter is designed and optimized using CST Software, Where a parametric study is used to optimize its geometric parameters. In our design, six periodic Hilbert cells are used, which are work collectively with three transverse slots to generate the desired resonance frequency. The used dielectric substrate is FR4 with a relative permittivity of 4.3. The proposed filter operates at the frequency of 3.25 GHz with an insertion loss about of −2 dB and a rejection extended from 1 GHz to 3.2 GHz and from 3.4 GHz to 7 GHz respectively for the lower and the higher sides with a level more than −35 dB. The filter is fabricated and measured, where the obtained measurements show a clear crystal similarity with the simulated results. The proposed filter is considered for TD LTE applications.

W-Band Low-Sidelobe Series-Fed Slot Array Antenna Based on Groove Gap Waveguide

In this letter, a low-sidelobe, high-efficiency, series-fed 2 × 24 slot array antenna at 93 GHz is proposed. The antenna can be divided into three separated layers and there is no need of electric contact between layers according to gap waveguide (GW) theory. To control the magnitude of the coupling energy and achieve −30 dB sidelobe quasi-Taylor weighing in radiation slots, transverse coupling slots in the middle layer are placed in a certain distance relative to the bottom gap waveguide center. Measure results agree well with simulation result, which demonstrates that the reflection coefficient of the antenna is lower than −10 dB from 91.6 to 94.4 GHz, with over 23 dB gain in the operating band. The 3 dB beamwidth of the E-plane pattern is lower than 4°, while the sidelobe level is lower than −20 dB. The whole antenna's efficiency is higher than 85%.