Band Operation Research Articles

Enhancing isolation performance of tilted Beam MIMO antenna for short-range millimeter wave applications

The research paper discusses the detailed designing of a compact, simple, and low-profile antenna that provides several desirable features. The antenna is engineered by using a substrate material called Roger 6002, and its dimensions are 12 mm × 6 mm × 1.52 mm. The single antenna element achieves a wideband frequency coverage of 24–30.2 GHz and a high gain of 9 dBi. To enhance the antenna's capabilities, a two-port multiple-input multiple-output (MIMO) configuration is employed by adding a second antenna element orthogonal to the first one. Although the operational band remains the same, the isolation between the two elements is found to be unsatisfactory. A C-shaped decoupling structure is established to address this issue, which effectively improves the isolation. Including the parasitic patch enhances the isolation from −18 dB to −29 dB. An antenna hardware sample is built and tested to validate the recommended work, and the outcomes are compared to the predicted results obtained from the software. The experimental and simulated data exhibit close agreement, confirming the accuracy of the design. Additionally, this outstanding performance in bandwidth and isolation compares with existing literature, presented in the form of a table. Various MIMO parameters are also examined, and it is found that they fall within acceptable ranges. The antenna demonstrates an Envelope Correlation Coefficient (ECC) of approximately 0.005 and a Diversity Gain (DG) of around 9.99 dB. The recommended antenna design is highly suitable for future miniature devices used in Internet of Things (IoT) applications.

Miura Type Transform Between Non-Abelian Volterra and Toda Lattices and Inverse Spectral Problem for Band Operators

Miura Type Transform Between Non-Abelian Volterra and Toda Lattices and Inverse Spectral Problem for Band Operators

High isolation frequency-reconfigurable UWB-MIMO antenna with on-demand WiMAX band elimination

Abstract In this article, a planar dual-element frequency reconfigurable multiple-input multiple-output (MIMO) antenna for ultra-wideband (UWB) applications is studied. The frequency band can be switched between UWB operation and single band rejected UWB performance using a pair of PIN diodes in the MIMO configuration. The presented antenna is comprised of two similar slotted circular radiators, having tapered microstrip feedlines and separate partial ground planes. An RT/Duroid 5880 substrate with size 54 × 54 mm2 is used for the design purpose. Rotational symmetry between the radiators and diagonally oriented t-shaped decoupling structure behind the substrate have been utilized for high isolation purpose. The designed MIMO antenna exhibits UWB performance in mode 1. In other mode, the antenna operates in the frequency range 2.46–10.44 GHz with Worldwide Interoperability for Microwave Access (WiMAX) band rejection. Thus, the MIMO antenna exhibits on-demand single band rejection behavior depending on the switching conditions of the diodes. The measured isolation is greater than −20 dB in both the modes. The presented MIMO configuration possesses compact and planar geometry with high gain, good isolation, ultrawideband performance with reconfigurable band elimination, high efficiency and efficient diversity performance parameters. The suggested antenna is a good choice to be utilized for portable UWB MIMO applications.

Design of a Crossed Dielectric Resonator-Loaded, Dual-Band Dual-Polarized Differential Patch Antenna with Improved Port Isolation and Gain

To meet the urgent requirement for more channel capacity in modern wireless communication systems, antennas with more operation bands are demanded. However, large amounts of antennas suffer from low radiation gains and low port isolation levels. In view of this, a differentially fed, dual-wideband, dual-polarized patch antenna is proposed in this paper. Compared with conventional crossed-feeding structures, the proposed crossed dielectric resonator (CDR) can provide extra resonances with improved isolation levels and radiation gain. Further, four shorting pins are introduced to the radiating patch to help improve the impedance-matching performance. In addition, the proposed antenna also has a very compact size of 0.46λ × 0.46λ × 0.12λ. Finally, a prototype of the proposed antenna is fabricated to validate the design concept. The measured results show that the proposed antenna generates dual wide bands of 1.86–2.52 GHz and 3.26–3.72 GHz for |S11| < −10 dB. High radiation gains of 8.9 ± 0.9 dBi and 10.8 ± 1.2 dBi are also obtained, as well as high port isolation levels of better than 38.4 dB and 36.2 dB at the two bands. The excellent performance of the proposed antenna makes it a promising candidate for 4G/5G wireless communication systems.

Means of Enhancing the Power Output and Widening the Operational Frequency Band of Vibration-Based Electromagnetic Energy Harvester

Means of Enhancing the Power Output and Widening the Operational Frequency Band of Vibration-Based Electromagnetic Energy Harvester

A Multi-Bandwidth Reconfigurable Patch Antenna for Devices in WLAN and UWB Technology Applications

This article introduces a process to design, simulate, and measure a novel multi-band patch antenna with different operation modes, i.e., band centers and bandwidths. Switching between operation modes is possible using a pair of PIN diodes to connect different parts of the antenna with the main antenna patch. Such a reconfigurable design allows for individual control of each frequency range. The main operation mode of the resulting antenna has an impedance bandwidth with two bands, one from 2.4 GHz to 2.73 GHz and another from 3.4 GHz to 5.73 GHz, with a maximum gain of 4.85 dBi and stable radiation patterns. The resulting antenna is suitable for applications using both ultra-wideband technologies and wireless local-area network (WLAN) technologies.

A Tunable Fano Resonator with High Sensitivity Based on Black Phosphorus in the Terahertz Band

A Fano resonator using black phosphorus, capable of tuning the operating band while possessing high sensitivity, is proposed. A ring and a groove are respectively etched above and below the main channel to produce the Fano resonance, resulting in a highly sensitive Fano resonator. Such a sensor can capture slight changes in the surrounding environment. Moreover, adding black phosphorus into the ring above the channel and into the groove below the channel, the electron doping of black phosphorus can be altered to adjust the resonant frequency of the Fano resonator. The shiftable frequency of the Fano resonator designed herein can reach 57 GHz at the second‐order resonance around 1.895 THz, an ability highly attractive in fields that require high sensitivity and adjustability. It is essential in the area of integrated electronics, offers fresh perspectives for innovations in integrated electronic gadgets, and paves the way for flexible terahertz systems.

Design of a quint-band antenna with a hybrid-AMC reflector for internet of vehicle applications

In this paper, a low-profile, high gain enhancement quint-band antenna system backed with a hybrid artificial magnetic conductor (AMC) reflector is proposed. Firstly, a quint-band microstrip antenna was designed. Its radiation patch looks like a Chinese knot composing of many slots and branches, and the ground plane is etched 8-shaped and cross-shaped grooves to form the defected ground structure (DGS). Then, a hybrid-AMC reflector was developed and placed underneath the antenna for improving its radiation performance. This hybrid-AMC reflector consists of a cross-shaped AMC array with twenty one-unit cells and four PEC patches. The AMC unit cell includes five nested rings producing five in-phase reflection bands which are perfectly coincident with the antenna’s five operation bands. On the basis of simulations, the antenna and the hybrid-AMC array were fabricated and tested. The measured results agree well with the simulated data, and show that the hybrid-AMC backed antenna system achieves five working frequency bands resonating at 2.45, 3.36, 4.6, 5.9 and 7.4 GHz with strong directional patterns. Thanks to the hybrid-AMC reflector, the maximum gain enhancement of the antenna reaches 7.3 dBi at 4.6 GHz. The proposed antenna system covers WLAN, WiMAX, 5G and satellite bands, and is suitable for multi-channel communications in Internet of vehicle applications.

An Eight-Element MIMO Antenna Array for NR Application

We propose an eight-element multiple-input multiple-output (MIMO) antenna array for 5G (fifth generation) New Radio (NR) applications in the n78 (3.3–3.8 GHz) band to achieve a high data rate. In the proposed work antenna elements have rectangular slots on the ground. Microstrip lines directly feed an open slot in this design. The dimensions of the open slot are 21.5 × 4 mm (0.24 λ × 0.046 λ at 3.5 GHz) and the slot covers 19.18% of the bandwidth in the frequency band 3.3–4 GHz. The eight antenna elements are arranged in such a way that they are coupled and also achieve an excellent degree of polarization. The proposed eight-element MIMO antenna array is fabricated and measured. Across the operation band, the measured isolation of the proposed antenna is −35 dB, −18 dB, −11 dB, −50 dB, −18 dB, −30db, −11 dB, and −35 dB for S12, S15, S26, S34, S53, S56, S64, and S78 respectively. The proposed antenna design can achieve desired antenna parameters, i.e. Isolation >11 dB, total efficiency >68%, and several MIMO performance characteristics are evaluated, including envelope correlation coefficient (ECC) < 0.03, the total active reflection coefficient (TARC) is −7 dB, the diversity gain (DG) is 9.96 dB and the channel capacity losses (CCL) is less than 0.02 were measured at desired bandwidth. The radiation pattern and antenna gain are also shown in this paper. The design is suitable for 5G communication networks.

A compact 4 × 4 reconfigurable MIMO antenna design with adjustable suppression of certain frequency bands within the UWB frequency range

This paper introduces a novel 4 × 4 multiple-input multiple-output (MIMO) antenna design with a reconfigurable operating band within the Ultra-Wideband (UWB) range. The antenna consists of four rectangular radiating elements arranged symmetrically and orthogonally on a defected ground plane. The design incorporates switching elements that allow adjustable and reversible suppression of specific bands within the UWB range, enabling the antenna to operate in three different modes: UWB, X-band, and dual-band with sub-6GHz and X-band. Thus, a single UWB antenna can serve as three different antennas, suppressing certain frequencies as required. To mitigate mutual coupling between adjacent antenna elements, four thin stubs are strategically placed at the center of the ground plane, forming a square with open corners. When one of the antenna elements is excited, this structure acts as an insulator, ensuring that the surface current is confined solely to that element and not induced in others. Experimental verification of the proposed design was performed by fabricating and testing the antenna. The results indicated good agreement between simulation and measurement data for various parameters, including S-parameters, radiation patterns, gains, and MIMO parameters such as envelope correlation coefficients (ECC), diversity gain (DG), mean effective gain (MEG), and total active reflection coefficient (TARC).

Frequency-Selective Surface-Based MIMO Antenna Array for 5G Millimeter-Wave Applications.

In this paper, a radiating element consisting of a modified circular patch is proposed for MIMO arrays for 5G millimeter-wave applications. The radiating elements in the proposed 2 × 2 MIMO antenna array are orthogonally configured relative to each other to mitigate mutual coupling that would otherwise degrade the performance of the MIMO system. The MIMO array was fabricated on Rogers RT/Duroid high-frequency substrate with a dielectric constant of 2.2, a thickness of 0.8 mm, and a loss tangent of 0.0009. The individual antenna in the array has a measured impedance bandwidth of 1.6 GHz from 27.25 to 28.85 GHz for S11 ≤ -10 dB, and the MIMO array has a gain of 7.2 dBi at 28 GHz with inter radiator isolation greater than 26 dB. The gain of the MIMO array was increased by introducing frequency-selective surface (FSS) consisting of 7 × 7 array of unit cells comprising rectangular C-shaped resonators, with one embedded inside the other with a central crisscross slotted patch. With the FSS, the gain of the MIMO array increased to 8.6 dBi at 28 GHz. The radiation from the array is directional and perpendicular to the plain of the MIMO array. Owing to the low coupling between the radiating elements in the MIMO array, its Envelope Correlation Coefficient (ECC) is less than 0.002, and its diversity gain (DG) is better than 9.99 dB in the 5G operating band centered at 28 GHz between 26.5 GHz and 29.5 GHz.

Spatial-Temporal Pattern and Driving Forces of Fractional Vegetation Coverage in Xiong’an New Area of China from 2005 to 2019

The Xiong’an New Area was officially established in 2018 to construct a new, intelligent, and efficient urban area to alleviate Beijing’s non-capital functions. Using Landsat satellite images, we employed the dimidiate pixel model, band operation, and transition matrix to analyze the temporal and spatial variations in FVC (Fractional Vegetation Coverage) within the Xiong’an New Area in 2005, 2013, and 2019, respectively. Urbanization rate, precipitation, temperature, and population were considered potential driving forces, which we analyzed using grey relational analysis and linear regression to explore the correlation between FVC and these factors. The findings are as follows: from 2005 to 2019, overall improvement and significant degradation have been observed. In Baiyangdian, a part of the national key ecological area, water bodies and FVC have increased. Grey relational analysis revealed that precipitation had the highest grey relational value of 0.76. The average correlation among natural factors was 0.67, while that among human factors was 0.60. Generally, the Xiong’an New Area vegetation exhibited instability, while Baiyangdian demonstrated relatively stable FVC. Grey relational analysis indicates a strong potential for social and economic development in the Xiong’an New Area.

Abstract P2044: Silencing The LncRNA Vesper During Right Ventricle Pressure Overload Worsens Hypertrophic Remodeling And Function

Pulmonary arterial hypertension (PAH) is a rare disease that includes familiar and idiopathic forms. Increased pressure in the pulmonary artery leads to pressure overload of the right ventricle (RV) and subsequent hypertrophic remodeling to maintain cardiac output (CO). While many therapies are available for the hypertrophic left ventricle (LV), the RV is known to involve distinct remodeling pathways and unfortunately, these are poorly understood, and no cure is available. To identify new regulatory mechanisms, total RNA sequencing was performed on hypertrophied mouse RV tissue. Focusing at differentially expressed long non-coding RNAs (lncRNAs), one specifically, Gm38399 , was observed to be consistently upregulated in the diseased RV compared to healthy controls. Compared to LV tissue, there was a similar expression at baseline, but interestingly, no increase in expression during LV hypertrophy. Therefore, we named this lncRNA right VE ntricular S pecific P ressure ov ER load ( Vesper ). To elucidate the mechanism, we determined the subcellular localization of Vesper , by subcellular fractioning followed by qPCR. Using Xist as nuclear, and Gapdh as cytoplasmic control, we found Vesper to be entirely nuclear. Furthermore, we were able to silence Vesper in vitro by using a specific GapmeR. Not only Vesper was silenced, but we also found two neighboring genes to be affected, namely Nav1 and Phlda3 . Interestingly, these genes were also differentially expressed in the diseased RVs. To determine the mechanism in vitro , chromatin isolation by RNA purification (ChIRP) was performed and the crosslinked RNA, DNA, proteins stored for further analysis. We also treated mice that underwent pulmonary artery banding (PAB) or sham surgery, with a weekly intraperitoneal injection of 10 mg/kg bodyweight GapmeR or a vehicle control. After 4 weeks, the mice underwent hemodynamic analysis before the RV tissue was isolated for histology and molecular analysis. Surprisingly, silencing of Vesper exacerbated pathologic RV remodeling, also in mice that received sham surgery. While further investigation is needed to understand the role of Vesper in PAH, our results so far suggest that expression of Vesper is necessary to maintain RV function during pressure overload.

Computer-aided design of quadra-ridged waveguide transformers for full-band matching of half-height rectangular waveguides

A quadra-ridged waveguide transformer (QRWT) is proposed for full-band matching between a standard waveguide and a half-height waveguide, which meets the need for compact waveguide components and the need for multiple sections of irregular transmission lines for better matching in wider operation bands. Unlike conventional matching circuits with monotonically changing impedances, QRWTs form abrupt cross-section changes between transmission line steps. The initial configuration of QRWT is built by CST MICROWAVE STUDIO, a system-level electromagnetic compatibility and general high frequency passive device simulation software, according to the basic electromagnetic (EM) concept and then is optimized by optimization functions from an advanced EM simulator, during the optimization, releasing restrictions as many as possible. To explain the concept, a sample QRWT is designed to match a standard rectangular waveguide WR34 to a half-height waveguide. The reflection coefficient is less than −24 dB in the full operation bandwidth, from 21.7 to 33 GHz. The optimized QRWT has a length of 3.088 mm, 0.218 times the waveguide wavelength at its center operation frequency of 27.35 GHz. For comparison, a two-stage quarter-wave transformer matching circuit is optimized. For similar reflection coefficients in the same bandwidth, the QRWT has a length 57% shorter than the conventional one, and it has an easier manufacturing method using wire-electrode cutting. To verify the design, a back-to-back matching circuit was fabricated using brass material without extra dielectric material. Its measured reflections are less than −16.6 dB, and the insertion loss is less than 0.2 dB.

Ultrawideband Dual Circularly Polarized Waveguide Array Antenna for K- and Ka-Bands Satellite Communications

In the letter, a wideband dual circularly polarized (CP) waveguide antenna array is designed for K and Ka dual-band satellite communications. A multi-stage square waveguide structure is exploited into the radiating part to facilitate the excitation of a dual polarization response. A ridge waveguide polarizer is integrated to form the left-hand circular polarization (LHCP) and the right-hand circular polarization (RHCP). For a better arrangement of the feeding network, a transition structure with E-plane waveguides to double-ridge waveguides reduces the cross-sectional area of the feeding network. An 8 x 8 array antenna prototype was designed, fabricated and measured for demonstration purposes. The axial ratio (AR) and impedance bandwidth of the array antenna are more than 45%, according to simulation and measurement results. Input reflection coefficient and isolation lower than -15 dB for the dual CP from 19 to 30 GHz, the total antenna efficiency for the entire operating band exceeded 72%. For both polarizations, the peak gain ranges between 24.6 and 28.8 dBi from 19 to 30 GHz.

Decoupling and Wide-Angle Scanning Design of a Millimeter-Wave Phased Array Using Square-Ring Metasurface

A wide-angle scanning millimeter-wave (mm-wave) phased array using square-ring metasurface (SRMS) is presented in this letter. SRMS not only improves the element gain owing to enhancing the radiation efficiency and directivity of the antenna element, but also decreases the mutual coupling between elements as a partially reflective surface. Due to the reduced mutual coupling, both the active impedance matching and the total efficiency of the proposed array are significantly improved. Further, thanks to the improved active impedance matching and the small element spacing of 0.43 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 27 GHz in free space), the 3-dB scanning angle of the proposed array is significantly extended. Measured results show that the phased array achieves a wide 3-dB scanning angle greater than ±68° over a wide operating band of 24. 11-29.68 GHz (20.7%), which is very suitable for 5G mm-wave terminal applications.

Design and Analysis of Modified U-Shaped Four Element MIMO Antenna for Dual-Band 5G Millimeter Wave Applications.

A novel compact-slotted four element multiple input multiple output (MIMO) planar monopole antenna is proposed for 5G mmWave N257/N258 and N262 band applications. The antenna, with dimensions of 12 mm × 11.6 mm × 0.508 mm (1.036λo ×1.001λo×0.043λo where λo is computed at lowest cutoff frequency), is fabricated on a Rogers RT/duroid 5880 (tm) substrate with a relative permittivity of 2.2 and a dielectric loss tangent of 0.0009. The suggested antenna consists of four U-shaped radiating elements (patches) on top of the dielectric material and a slotted ground on the bottom. The radiating elements are fed by a 50-ohm microstrip line feed. To improve the impedance performance of the MIMO antenna, a rectangular strip of 1.3 mm × 0.2 mm and a couple of rectangular slots are added to each radiating element. The first operating band at 27.1 GHz, ranging from 25.9 GHz to 27.8 GHz, is achieved by using slotted U-shaped radiating elements. The second operating band at 48.7 GHz, ranging from 47.1 GHz to 49.9 GHz, is obtained by etching hexagonal slots on the ground. The antenna design achieves an isolation of >27 dB through the orthogonal positioning of radiating elements and slots on the ground. The designed antenna operates at 27 GHz (N257/N258) and 48.7 GHz (N262) bands, exhibiting stable radiation patterns, a peak gain of >5.95 dBi, radiation efficiency of >90%, an envelope correlation coefficient of <10-6, a total active reflection coefficient of ≤-10 dB, channel capacity losses of <0.03 bits/s/Hz, and a mean effective gain of ≤-3 dB. The simulated and measured results of the antenna show good agreement, making it well-suited for 5G mmWave communication applications.

Subwavelength grating-based silicon photonic TE mode division multiplexer for C + L band operation

This paper reports a subwavelength grating (SWG) based multiplexer (MUX) on a silicon photonics platform capable of multiplexing three transverse electric modes. The designed MUX is simulated using a commercial 3D finite-difference time-domain solver and shows broadband operation over the whole C and L optical telecom bands from 1530 nm to 1625 nm wavelength range. The effective indices of the Bloch modes in the SWG waveguides are extracted from the band structure plot. The designed MUX consists of two co-directional coupling regions for fundamental to higher-order mode coupling, with each coupling stage consisting of single-mode and multimode SWG waveguides. The transmission characteristics, viz. transmittance, insertion loss, and return loss, are presented and discussed. The coupling lengths without the tapering regions for TE0–TE1 and TE0–TE2 mode couplings are 14μm and 1.48μm, respectively. The transmittance is >78% with the highest insertion loss and return loss of 1.1 dB and –15 dB, respectively. At 1550 nm, the transmission is >88%, insertion loss is <0.6 dB, and return loss is <−15 dB. A uniform under-etch and over-etch of 5 nm are taken for the fabrication tolerance study, which shows a maximum variation of 0.58 dB for the insertion loss with return loss <−14.6 dB at 1550 nm. Over the whole simulated range, the insertion loss is <1.4 dB, and return loss is <−14.6 dB with ±10 nm change in device dimension. A temperature tolerance study with 50 °C and 100 °C rise in temperature has been done, and the device retains its broadband operation over the simulated range. The maximum increase in insertion loss is 0.1 dB for the TE0–TE2 coupling, while the overall return loss of the device decreases to <−20 dB for the TE0–TE1 coupling.

Fully-Metallic Additively Manufactured Monolithic Double-Ridged Waveguide Rotman Lens in the K/Ka-Band.

This paper reports on the design and experimental validation of a fully-metallic double-ridged waveguide 10 × 10 Rotman lens additively manufactured as a single part. The wide band operation of this quasi-optical beamformer enables us to cover the uplink and downlink frequencies allocated to satellite communications in the K/Ka-band, from 17.3 GHz to 30 GHz. The feeding port design was adjusted to enable vertical printing, thus minimizing the use of supporting structures. A prototype was manufactured and tested. The reported results indicate losses in the range of 0.5 dB in the lower-frequency band and 0.8 dB in the upper-frequency band, including the waveguide transitions added for test purposes. The measured reflection and coupling coefficients remain below -11.5 dB over the operating band. The standard deviation of the residual phase error across the array ports is below 5° in simulation and below 10° in measurements. Array factors synthesized using the scattering parameters confirm the good stability of the beamforming functionality over the wide frequency band analyzed. This monolithic design is a promising step toward more integrated antenna systems, such as a compact dual-stack configuration for planar array design.

Low-profile dual-polarized differential-fed filtering antenna and its novel array with low sidelobe level

This paper presents a single-layer dual-polarized filtering antenna with good out-of-band suppression. By using inherent characteristic of the patch’s eigenmode and meanwhile merging four filtering strategies, i.e., parasitic patches, slot on the driving patch, and defected groundstructure (DGS), a low-profile filtering antenna design with five radiation nulls has been realized. With the designed filtering antenna, a conventional 1×2 array with a spacing of 0.91λ is first developed. In order to reduce the sidelobe level of the array, a sharing patching scheme is introduced to decrease the interspace between the elements as 0.44λ, with the same physical size as the conventional array. In addition, a concept to measure total isolation between two kinds of the polarized ports in the array, i.e., SddVH, has been derived for the first time. The prototype of the proposed array is fabricated with a profile of 0.038λ. Measured results indicate that the designed novel array has an operational band of 3.53–4.06 GHz, SddVH better than 41 dB, a sidelobe level below −18 dB, and a suppression level above 20 dB with the stopband up to 0.5 GHz and 5 GHz.