Cross Slot Research Articles

A Cross-Shaped Slotted Patch Sensor Antenna for Ice and Frost Detection

Beyond data transmission, antennas have recently been utilized as sensors, offering the advantage of reducing hardware requirements and power consumption compared to systems where sensors are separate from antennas. Patch antennas, in particular, are widely used across various applications, including sensing, due to their attractive features like compact size and conformability. In addition, they can be easily designed in different ways to sense variations in certain variables. Adding a slot to the patch antenna introduces several advantages, including multiband, wideband operation, and improved impedance bandwidth. Slots also provide a concentrated region of electromagnetic fields, which increases the antenna’s sensitivity for sensing and detection purposes. In this paper, a rectangular patch antenna with a cross slot is designed and proposed for water, ice, and frost detection. Detection is achieved by measuring variations in the resonant frequency in response to water, ice accumulation, and frost. The results indicate that the proposed antenna can detect both water and ice accretion with a frequency shift of up to 1.538, 0.358, and 0.056 GHz, respectively, which reflects good sensitivity levels of the antenna. The effect of the slot on strengthening the near electric field and antenna sensitivity is discussed in this paper. The antenna is fabricated and measured and the indicators of each detection scale have been extracted. The proposed antenna has a simple structure and a small size of (40 × 40 × 1.53 m3). In addition, it can be precisely used to sense different environmental parameters such as frost and ice. Thus, it can serve as a strong candidate for detecting natural disasters like frost damage. Furthermore, the findings in this paper offer valuable insights into how the presence and structure of slots influence the sensitivity response of patch antennas, supporting ongoing research in this field.

Ultrawideband low RCS metasurface based on optimized multielement phase cancellation and diffusion reflection

Abstract A novel metasurface (MTS) based on optimized multielement phase cancellation and diffusion reflection is proposed for ultrawideband radar cross section reduction (RCSR). The unit cell of the MTS consists of a rectangular patch on the top layer, a cross slot in the center layer, and a ground plane on the bottom layer. The periodic array of the unit cells converts the linear polarization wave to its cross-polarization in the band of 5.17–7.74 GHz. To extend the bandwidth of RCSR, the height and the arrangement of the proposed unit cells and their mirror unit cells are optimized through the particle swarm optimization algorithm to achieve optimized multielement phase cancellation and diffusion reflection. The simulation and measurement results show that the proposed MTS achieves 10 dB RCSR from 5.8–70.6 GHz, with high angular stability and polarization insensitivity performance.

Circularly polarized twin port tunable silicon-graphene antenna with beam tilting characteristics for THz based 6G communication system

Abstract This communication explains the design and analyse of a twin port silicon-graphene aerial. The intended aerial has three distinct features: (i) stimulation of ceramics through uneven cross slot produces the circularly polarised waves from 3.45 THz to 3.65 THz; (ii) a mirror arrangement of uneven cross-shaped slot increases separation between ports by almost 25 dB; and (iii) suspension of partial reflecting surface over twin port antenna slants the radiation pattern by ±45°. A sheet of graphene over silicon creates the tunablity in terms of working band and circularly polarized band by altering its chemical potential. The optimized result from HFSS is compared to the CST EM tool, and it is determined that the suggested aerial functions well in the 3.25–3.75 THz range with a peak gain of 3.5 dBi. By including pattern diversity characteristics, the suggested antenna’s multi-port parameters are improved, and it becomes suitable for THz-built 6 G wireless applications.

High-order-mode cavity fed 45° linear polarized antenna for 5G applications

Abstract In this paper, a high-order-mode (HOM) (TE330) cavity-fed 45° linear polarized 6×6 slot array antenna is proposed. The 45° linear polarization is achieved by introducing asymmetric cross slots on the HOM cavity, resulting in low profile and wide bandwidth. The antenna array was verified using standard printed circuit board technology. Measured results show that the impedance bandwidth ( $|S_{11}|\le$ −10 dB) is 13.9% (36.98–42.92 GHz), and the peak gain is 19.3 dBi with a 3-dB gain bandwidth of 13.6%. Attributed to its simple structure, low profile, and wide bandwidth, the presented antenna is a good candidate for 5G applications.

Effects of Ribbed Crossflow Channel in a Turbine Blade on Film Cooling Performance of Diffusion Slot Holes with Various Cross Section Orientations

Abstract This paper investigates the influence of ribbed crossflow on the film cooling performance of a turbine rotor blade. A pressure-sensitive paint measurement technique was employed to measure the effectiveness of film cooling. The discharge coefficients were also measured to determine the flow resistance. A row of film holes was positioned at the pressure surface or suction surface with a spanwise hole spacing of 7.5D, which is half of the rib spacing. The experiments were carried out at a mainstream Reynolds number of 520,000, a turbulence intensity of 3.6%, and a density ratio of 0.97. The crossflow inlet velocity was 45% of the cascade inlet velocity. A fan-shaped hole with a 14 deg expansion angle (Fans-14), a horizontally oriented slot cross section diffusion hole with a 14 deg expansion angle (H1.7-14), and two vertically oriented slot cross section diffusion holes with 14 deg (V1.7-14) and 20 deg (V1.7-20) expansion angles were tested with/without crossflow. The results indicated that the slot cross-sectional orientation significantly changes the flow patterns inside the holes. H1.7-14 has stronger lateral expansion and better surface adhesion, while V1.7-14 and V1.7-20 yield more uniform lateral velocity distributions. Regardless of crossflow, H1.7-14 produces the highest film effectiveness and discharge coefficient on the pressure surface, while it changes to V1.7-20 on the suction surface. The ribbed crossflow increases the film effectiveness on both the pressure surface and suction surface, except for V1.7-20, as it is almost unaffected by the crossflow.

Substrate-Integrated Cylindrical Cavity Controlled Hexa-Polarization Flexible Cylindrical Dielectric Resonator Antenna for Ku-Band Applications

A substrate-integrated cylindrical cavity (SICC) fed polarization flexible cylindrical dielectric resonator antenna (CDRA) is presented in this literature. To excite the CDRA, a unique and simple feeding approach based on substrate-integrated waveguide (SIW) technology is demonstrated. This SICC is fed by two 50Ω microstrip lines, oriented orthogonally to each other. The SICC with a cross slot on its top metalized surface and the TM110 mode excites inside it act together to couple energy efficiently to the CDRA. Applying different phase combinations signals at the two input ports of the SICC, the CDRA can radiate in four different orientations linear polarization (LP) (along φ = 0°, 45°, −45°, and 90° ), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP). A conventional cylindrical dielectric resonator having relative permittivity ϵd = 10 is preferred. Its diameter, height, and cross-slot dimensions are optimized to operate the CDRA over Ku-band with 12% impedance bandwidth, 2-dB axial ratio (AR) bandwidth of 11%, and 3-dB gain bandwidth of 12%. In this operating band, CDRA resonates at three different higher-order modes (HEM32δ, HEM113, and HEM12δ+2) with 8 ± 1.6 dBi/dBic gain for all the polarization states. The measurements of this antenna are conducted using two external phase shifters and one power divider.

Metasurface loaded dual port circularly polarized dielectric resonator antenna with reduced RADAR cross section and mutual coupling features

The design of dual port radiator with a polarization diversity technique and reduced radar cross section (RCS) is described in this study. Cross slot is used to stimulate cylindrical ceramic for generating circular polarization features. Mirror orientation of aperture between port-1 and port-2 improves the isolation level by 25 dB. To suppress the antenna’s monostatic RCS, split ring resonator (SRR) based frequency selective surface is positioned between and around the dual ports. Experimental outcomes confirm the designed radiator operates from 4.11–5.24 GHz along with 3-dB axial ratio in between 4.15–4.92 GHz. The value of monostatic RCS is reduced by 15 dBsm in between the operating band. Broadsided radiation characteristics and good value of diversity parameter makes the designed radiator applicable for C-band Radar applications.

Design and optimization of a dual port high gain circularly polarized graphene-ceramic array antenna in a THz regime

In this paper, a dual port high gain hybrid (silicon graphene) antenna is designed and investigated. Some of the important qualities of the proposed radiating structure include the following: (1) XGBoost and Random Forest-based machine learning (ML) techniques are applied to predict the reflection coefficient (|S11|) features of the designed radiator to reduce the simulation time; (2) the use of a cross slot provides the circularly polarized waves between 4.92 and 5.38 THz; (3) a 1∗2 array structure produces the high gain, i.e., 10.0 dBi within the operating frequency range; and (4) the opposite orientation of the aperture provides a polarization diversity concept, which, in turn, improves the isolation level to more than 30 dB. After comparing the results obtained from CST and HFSS, as well as those predicted from the ML algorithm, it is confirmed that the designed radiator operates from 4.71 to 5.85 THz. The good value of far-field and diversity parameters affirms the fitness of the designed radiator for wireless power transfer in the THz regime.

A broadband second-order bandpass frequency selective surface for microwave and millimeter wave application.

This paper presents a frequency selective surface (FSS) with a wideband second-order bandpass response in the dual-band of microwave and millimeter wave. The overall structure consists of three layers of metal pattern and two layers of thin dielectric substrate. The top and bottom metal layers have capacitive patches with integrated curled Jerusalem cross slot resonators, while the intermediate metal layer has an inductive grid structure with cross-shaped slot resonators. The incorporated slot resonators play a pivotal role in achieving the desired transmission poles or zeros, which enable a wideband second-order filtering response in the dual-band and a quick roll-off at the passband edges, increasing the efficacy of electromagnetic shielding. To fully investigate the structure's frequency response, an equivalent circuit model of the structure is created, spanning the complete frequency range of 5-50 GHz. Physical samples are created and measured to confirm the suggested approach's efficacy. The passband center frequencies of the FSS are found at f1 = 19.42 GHz and f2 = 42.78 GHz, and the - 3dB bandwidth is 4.34 GHz (17.25-21.59 GHz) and 8.54 GHz (38.51-47.05 GHz), respectively. The simulation results align well with the experimental data. The transmission response rapidly transitions from the passband to the stopband at the passband boundaries.

Fusion design of six-port waveguide coupler integrating tight and loose coupling

This paper introduces a fusion design method of a six-port waveguide (WG) coupler integrating tight and loose coupling together. The couplers exhibit a compact size due to the stacked configuration of three WGs. A methodology for designing the integrating tight and loose coupler is presented. The tight and loose coupling is achieved by setting a rectangular slot in the common narrow wall along with one or two cross slots in the common broad wall. Inspired by the superposition of TE10 and TE20 modes used to design the short-slot −3-dB coupler. The loose-coupling part of the fusion design is analyzed theoretically utilizing modes superposition. Based on the theoretical analysis, the loose coupling can be precisely designed, meanwhile, low coupling-level fluctuation can be obtained in the operating band. For demonstration, two design examples are designed and a prototype centered at about 3.73 GHz is fabricated. The fractional bandwidth (FBW) (|S11| < −15 dB) is about 28.4 %. Within it, the tight coupling (−3 dB) coupler achieves ± 0.5 dB amplitude imbalance. Meanwhile, the loose coupling (−20 dB) coupler achieves little fluctuation of < 0.56 dB and its isolation is better than 25 dB.

DGS Based CP Antenna for 5G Communication with Harmonic

Higher harmonics in antennas contribute to negative effects on antenna performance such as interference, radiation pattern distortion, impedance mismatch and increased complexity in design, commonly occurring in RF communication systems caused by the non-uniformity of the antenna structure and the presence of parasitic elements. Therefore, a patch antenna operating at 3.65GHz for 5G mobile communication that incorporates techniques to suppress unwanted higher harmonics is presented. The antenna design employs a basic rectangular patch antenna with an inset feed technique to enhance the S11 parameters at the resonant frequency. Additionally, two dumbbell defected ground structures (DGS) are employed to minimize the higher modes of harmonic distortion. To transform the antenna into a circular polarized (CP) antenna, two truncated corners and a cross slot perpendicular to the middle of the patch are introduced. The proposed antenna is able to suppress unwanted harmonics at higher resonances, demonstrating its effectiveness in mitigating harmonic distortion

Design of a Dual-band Wearable Antenna Operating at 2.45 GHz and 5.8 GHz for Medical Communication Applications

Indonesia's natural demographic which consists of 16,771 islands makes it has many challenges in infrastructure development, especially in the health sector. According to data, Indonesia currently has 10,203 Puskesmas and 2,449 hospitals. In terms of the number of medical personnel, currently in Indonesia there are 124,449 medical personnel. However, of the large number of medical personnel, 61.12% are concentrated in Java and Bali. This inequality causes the need for a technology that makes it easier for medical personnel to provide services to the community. Wireless Body Area Network (WBAN) is one of developed technology that supports telemedical services. In WBAN, wearable antenna is needed as a transmitter to transmit data. In this paper, a compact wearable dual band antenna was designed in ISM frequency band of 2.45 GHz and 5.8 GHz. A combination of rectangular shape radiating structure and cross slot is constructed to achieve dual band frequency. Jeans Textile material with permitivity of 1.7 and thickness of 1 mm is used for fabricating the proposed antenna. The size of antenna is 52.3mm x 58.69mm. The proposed antenna is simulated with and without human body panthom using cst software. The simulations result indicates that antenna resonates at frequency 2.45 GHz and 5.8 GHz with peak gains of 6.92 dBi and 6.5 dBi. SAR values when the proposed antenna simulated at wrist phantom ​​are 0.326W/kg and 1.024W/kg. When simulated at chest phantom, the SAR values ​​are 0.554W/kg and 0.394W/kg. Therefore, The proposed wearable antenna design is well suited for telemedical services.

Switchable visible and near-infrared light bifocal lens based on hybrid graphene-metasurface structures

We propose a wideband visible (VIS) and near infrared (NIR) light reflective flat lens with switching capability base on hybrid graphene-metasurface structure. This tunable flat lens structure consists of a slotted gold reflector substrate, a graphene monolayer and TiO2 nanofins that provide excellent focusing performance and tunability in the VIS and NIR range. In order to achieve the switching feature, a bi-functional device capable of switching reflection/absorption modes is required. To this end, the gold substrate with two cross slots has been used to create absorption properties and a graphene layer has been used to change the intensity of absorption and reflection. The switching property for incident light with circular polarization arises from uniformly changing the chemical potential of the graphene layer. By setting the chemical potential of graphene, μc, equal to 1.1 eV, we obtained the reflection property. The reflection mode exhibits a broadband (715–800 nm) optical response with high polarization conversion efficiency (more than 70 %). On the other hand, by choosing μc = 0.75 eV, the absorption feature is created at the wavelength of 700–780 nm. The reflected light can be focused on an arbitrary position above the structure by rotating the TiO2 nanofins with the help of Pancharatnam-Berry (PB) phase theory. In addition to obtaining the single and dual focus tunable flat lenses, we have also presented a multifunction configuration that can switch between different modes, such as non-focus, single and dual focus modes. Such switchable flat lenses can have various applications in imaging and sensing systems.

Multi band multi polarised fractal antenna for white space TV band

ABSTRACT Designing a fractal antenna for white space TV band frequencies is the main goal of the suggested work. In this design 4 iteration Koch snowflakes patch is used to get multiband. As the number of iterations increased size of the antenna is going to reduce. Further 4th iteration Koch snowflakes slots have been created in the patch. By introducing a fourth iteration cross slot into the ground plane, three bands have been created. Circular polarisation is attained through the incorporation of cross slots in the ground plane, inducing a phase shift between vertically and horizontally polarised electromagnetic waves. The antenna primarily operates within the last frequency bands (686–806 MHz) with linear polarisation. However, it can also function in the initial frequency band (487–540 MHz) with left-hand circular polarisation. The physical size if antenna is reduced by 38 mm with a gain of 4.5dBi. Axial ratio bandwidth (481–552 MHz) is 71 MHz. Axial ratio bandwidth is 18 MHz more as compared to impedance bandwidth. The same antenna can work in linear polarisation as well as circular polarisation. Multi-polarised, multiband antenna with impedance bandwidth of 10.3% (1st band) and 16.08% (last band) is designed for white space TV band frequencies.

A Method of Reducing Coupling between PIFAs Using Cross Slot Defected Ground Structure

A Method of Reducing Coupling between PIFAs Using Cross Slot Defected Ground Structure

Design and characterization of a circularly polarized microstrip-line-fed slot array antenna for S-band applications

A 2×2 slot array antenna fed by microstrip line for circular polarization operated in the S band frequency range is designed in this paper. Single cross slot with single port feed as well as dual port feed is taken into consideration for realizing circular polarization and combining these two processes, the slot array is designed with single feed for circular polarization. The antennas are designed on a Teflon glass fiber substrate of thickness 0.8 mm. The slot array dimension is 120×142×1.636 mm&lt;sup&gt;3&lt;/sup&gt;. Smith chart of single cross slot antenna with single feed as well as dual feed has a dip at 2.69 and 2.53 GHz respectively indicate the capability of realizing circular polarization in the S band frequency range. The return loss of the slot array antenna is -58 dB shows good input impedance matching of the antenna. A dip in the smith chart of the slot array shows circular polarization near 2.4 GHz ensuring wireless applications as well. Axial ratio is found to be less than 1 dB in the resonance frequency. The impedance bandwidth percentage of the slot array antenna is 12.24%. The simulation is done by using keysight advanced design system (ADS) software.

Miniaturized quad-band bandpass filter using quad-mode stepped impedance resonator

ABSTRACT A miniaturized quad-band bandpass filter (BPF) using compact quad-mode stepped impedance resonator (IQMSIR) is proposed. Based on the symmetric presented by the resonator, four modes are deduced using even-and odd-mode technique. Design formulas are also derived and they are used to guide the filter design. Multiple coupling circuit technique is employed to realize the four passbands. Independent design for four passbands are achieved due to the physical dimensions and additional cross slots. Upper stopband is performed by adding open loop SIR at I/O ports. Transmission zeros among each passbands are generated, resulting in high isolation and selectivity. A quad-band filter is designed, fabricated and measured. The operating central frequencies of the fabricated filter are at 2.54/3.36/5.24/6.6 GHz. The measured 3-dB fractional bandwidths of the four passbands are about 3.9/6.4/4/4.6% and the minimum insertion losses are about 2.3/0.89/3.2/2.3 dB. Measurements correlate well with the simulation results.

Circularly Polarized Multiple-Input Multiple-Output Dielectric Resonator Antenna for 5G Millimeter-Wave Application

A circularly polarized (CP) multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) is presented in this paper for 5G millimeter-wave (mm-wave) applications. This MIMO antenna consists of two high-order mode CP DRAs, which use the modified cross slots to generate the CP fields. Two complementary split ring resonators (CSRR) are used to isolate the surface current on the metal ground, which can increase the antenna isolation and optimize the axial ratio when each port is excited. The proposed MIMO antenna obtains a simulated impedance bandwidth from 25.41 to 31.18 GHz and an axial ratio (AR) bandwidth (AR &lt; 3 dB) from 25.49 to 29.52 GHz for the 5th generation wireless communication applications. The measured results show that the antenna covers the overlapped bandwidth of 11% and isolation less than −25 dB over the frequency band range. The measured average (peak) gain is 5.84 (6.24) dBic at 26.5 GHz to 29.5 GHz for port 1 and 6.90 (7.27) dBic for port 2.

A Triple-Band Broadband Miniature Antenna Design for Implantable Continuous Glucose Monitoring

This paper presents a miniaturized triband implantable planar antenna that covers the industrial, scientific, and medical (ISM) band and the Wireless Medical Telemetry Service (WMTS) band which can be used in a continuous blood glucose monitoring device. The antenna consists of a slotted radiating patch and a ground plane with a cross slot to miniaturize its size. The overall antenna size is only 51.35 mm3 (7.6 × 7.6 × 0.889 mm3) due to the reduced size by the slotting technique. Compared to other implantable antennas with similar performance, the proposed antenna is smaller in size, simple in construction, and easy to be fabricated. By cutting a cross slot in GND, impedance matching is improved, especially at the two higher frequency bands. We have fabricated the prototype and carried out measurements. The results show its gains are −32.2 dBi, −18.8 dBi, and −19.1 dBi at 0.9 GHz, 1.4 GHz, and 2.45 GHz, respectively. Its radiation patterns have good symmetry in the two lower operating frequency bands. In addition, the maximum SAR values comply with the IEEE standard safety guidelines (IEEE C95.1-2019).

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.