Ground Plane Research Articles

Design optimization for microstrip antennas based on polymethyl methacrylate (PMMA) substrate and carbon nanotube (CNT) conductive material in sub-6 Ghz band

Abstract Background The rapid expansion of modern smart applications, demanding faster data transfer and extensive bandwidth, has prompted the development of new-generation networks like 5G and 6G. These networks encompass additional frequency bands such as sub-6 GHz, millimeter waves, and terahertz bands to meet the growing bandwidth requirements. However, despite the substantial bandwidth available in these bands, several challenges must be addressed to overcome unfavorable propagation characteristics. Moreover, numerous applications necessitate wireless devices with antennas that exhibit high flexibility and exceptional radiation responses, particularly when subjected to bending effects. This requirement highlights the importance of polymers-based antennas that can adapt to changing conditions while maintaining optimal performance. The present comprehensive study delves into the performance evaluation of rectangular and circular microstrip antennas utilizing PMMA (polymethyl methacrylate) polymer substrate with varying thicknesses. Results Notably, CNTs (Carbon Nanotubes) are employed as an alternative to traditional copper for the conductive part and ground plane. Both PMMA-based antennas, integrated with CNTs, exhibit a compact footprint of 27.8 × 47.8 × 1.5 mm3 for the circular antenna and 22.8 × 39.5 × 1.5 mm3 for the rectangular antenna. Impressively, the realized gain of both antennas surpasses 5 dBi, demonstrating robust performance in both flat and bending scenarios across different substrate thicknesses. Conclusions The rectangular antenna achieves a bandwidth of approximately 200 MHz, while the circular microstrip antenna showcase annotable bandwidth of 500 MHz. These exceptional outcomes position the two microstrip antennas as highly suitable for a diverse range of emerging applications within the sub-6 GHz band (the frequency range below 6 GHz in the radio spectrum). Thus, the combination of PMMA substrate, CNTs and the compact form factor of the antennas presents a compelling solution for meeting the demands of modern applications requiring efficient wireless communication with enhanced performance and bandwidth.

A broadband dual-polarized antenna for 5G wireless communication systems

This article presents a broadband dual-polarized antenna for the 5G wireless communication technology. A ring resonator is chosen with the purpose of enhancing the axial ratio (AR) and impedance bandwidth. Partial ground plane is chosen with a slot placed beneath the feedline. The dimensions of the antenna are 50 mm × 50 mm × 1.6 mm, and it is fabricated on a dielectric substrate made of FR4 material. The variation of antenna polarization is achieved through the function of PIN diode. When the diode is in the ON state, the antenna functions as a wideband antenna that exhibits right hand circular polarization (RHCP). The frequency range covered by this system spans from 4.5 GHz to 7.5 GHz. Conversely, it provides linear polarization (LP) within a frequency range that spans from 4.3 GHz to 5.3 GHz. The metrics of the prototype antenna are measured and tested. The CST full wave simulator is utilized for conducting simulations.

Compact body‐worn MIMO antenna with high port isolation for UWB applications

SummaryThis article investigates the mutual coupling reduction of a compact two elements wearable ultra‐wideband (UWB) multiple‐input multiple‐output (MIMO) antenna. The ground plane of the proposed wearable MIMO antenna structure consists of three connected square ring‐shaped stubs and two rectangular slots of narrow height. These ground stubs and slots minimize the mutual coupling effect between antennas and provide high isolation. The suggested MIMO antenna functions from the 1.87 to 13.82 GHz frequency spectrum covering WLAN (2.4–2.484 GHz), UWB (3.1–10.6 GHz), and X band (8–12 GHz) with 152.32% fractional bandwidth. It sustains port isolation above 27 dB throughout the 2 to 13.82 GHz frequency band. Inside the whole working frequency band, the suggested antenna offers a tiny envelope correlation coefficient (ECC < 0.098), greater diversity gain (DG > 9.93 dB), minimum channel capacity loss (CCL < 0.32 bits/s/Hz), and slight magnitude variation in mean effective gain of antenna ports (< 0.1 dB). The recommended antenna yields a SAR level below the designated threshold (<1.6 W/kg), affirming its suitability for body‐worn applications. The designed MIMO antenna structure has an overall volume of 32 × 48 × 1.5 mm3.

Tunable VO2 metasurface for reflective terahertz linear and circular polarization wavefront manipulation at two frequencies independently

In this work, a tunable VO2 metasurface (MS) is proposed and numerically demonstrated in the terahertz (THz) region, which can independently manipulate reflected linearly polarized (LP) and circularly polarized (CP) wavefronts at two frequencies independently. The unit-cell of the proposed VO2 MS consists of a metallic circular ring (CR) structure, rectangular-shaped-patch (RSP) and circular-double-split-ring (CDSR) structure VO2 adhered on a dielectric substrate by a bottom metallic ground plane. The proposed MS structure enables the reflected cross-polarization conversion of LP waves at lower frequencies (fL = 1.34 THz) and CP waves at higher frequencies (fH = 2.53 THz), respectively. By changing the external temperature, the conductivity of the VO2 RSP and CDSR structures can be adjusted dynamically. By varying the conductivity of the VO2, the proposed MS can achieve a reflected LP conversion with efficiency from 0% to 98.86% at lower frequency of 1.34 THz and the reflected CP conversion with efficiency from 0% to 81.86% at higher frequency of 2.53 THz. Moreover, the corresponding modulation depths of this MS are as high as 98.86% and 81.86% at two different frequencies, respectively. Moreover, a 2π phase shift can be realized by the transmission phase and geometric phase principles at lower and higher frequencies, respectively. Finally, two VO2 MSs have been constructed to achieve the reflection deflection for both CP and LP waves, and reflective CP focusing and LP vortex beam generation, respectively. These findings are favorable for expanding the range of temperature-controlled VO2 MS for wavefront manipulation, thereby opening up new possibilities for the development of advanced, tunable, and multifunctional THz devices that can handle both LP and CP waves.

Dual-Notched UWB Orthogonal MIMO Antenna with Improved Gain Characteristics Using Frequency Selective Surfaces for Wireless Communication Applications

In this paper, a complementary split ring resonator (CSRR) loaded compact CPW-fed circular shaped monopole UWB antenna with dual band notch characteristics is designed on an FR-4 substrate. The propounded band-notched UWB antenna is integrated with two frequency selective surface layers referred as bandpass frequency selective surface (FSS-1) and reflector (FSS-2) to offer enhanced radiation performance. Bandpass FSS-1 enhances the gain of the antenna by improving directivity and reflector FSS-2 reflects back the backside radiation of the proposed antenna towards the forward direction thereby increasing gain and directivity of the proposed antenna. Furthermore, a two-element orthogonal MIMO antenna is proposed with improved gain using two FSS layers. The complete configuration of the proposed two-element MIMO antenna consists of CSRR-based radiating patches, monopole ground planes and two integrated FSS layers. The proposed MIMO antenna operates in UWB range from 3.46[Formula: see text]GHz to 16.02[Formula: see text]GHz with dual notches at 3.9[Formula: see text]GHz and 7.2[Formula: see text]GHz. Isolation between MIMO elements is greater than 23 dB. Both antennas are fabricated and investigated at 5.9[Formula: see text]GHz for vehicular communications. Maximum gain improvements of 8 dB and 6.4 dB are observed in case of the presented single element and MIMO antenna within the entire operating band due to the integration of dual FSS layers. The diversity performance of the suggested MIMO antenna is investigated by analyzing mean effective gain, envelope correlation coefficient, channel capacity loss and diversity gain parameters. The proposed MIMO antenna is a suitable candidate for vehicular and UWB wireless communication applications.

Aerodynamic characteristics of a delta wing aircraft under ground effect

The main objective of this study is to investigate the impact of ground effects on the aerodynamic coefficients of a delta wing aircraft model. Since the flow on the delta wing exhibits vortical flow inherently, it is crucial to examine the influence of ground effects under these conditions. An experimental study was conducted to enhance understanding of the aerodynamic behavior of an aircraft model incorporating a delta wing-body-vertical tail. Experiments were conducted in a subsonic wind tunnel with a test section measuring 2.8 m × 2.2 m. Measurements were taken using a sting type balance to determine the aerodynamic forces and moments. All experimental tests were performed at a Reynolds number of 1.5 × 106, with the specific aim of examining and identifying the influence of the ground on aerodynamic coefficients. To investigate how ground effect affects the aerodynamic performance of the model, a fixed plate with an adjustable height was placed underneath it. The distance between the model and the ground was varied, and resulting data indicated that increased proximity to the ground improved longitudinal static stability. The results revealed that the presence of the ground plane resulted in a 6% increase in the maximum lift coefficient. Meanwhile, the lift increases around 25% due to ground effects at an angle of attack of 14° as it approaches the ground. The lift coefficient was enhanced across all angles of attack, while the induced drag coefficient decreased, resulting in an overall increase in aerodynamic efficiency. The lift curve slope saw a 16.9% increase when the model’s height from the ground plane was less than half of the wing span. As the height decreased further, the aerodynamic center shifted backward, leading to an increase in longitudinal static stability. The rolling moment and yawing moment coefficients becomes unstable at angles of attack above 30°.

A miniaturized airplane blade antenna for radio navigation and communication systems

Blade antennas are preferred antenna structures for airborne applications due to their compact size, lightweight and drag-reducing aerodynamic shape. In this paper, we present the design, simulation and realization of a miniaturized blade antenna requiring a small ground plane and covering the frequency band 0.8–1.1 GHz. To reduce air drag, the proposed antenna is placed inside an aerodynamically optimized airborne radome. The return loss, the radiation patterns and the realized gain of the proposed antenna are studied using HFSS simulations. The comparison of the simulated return loss and radiation patterns to their measured counterpart demonstrates a good agreement. A minimum realized gain of 3.6 dB was achieved at the frequency of 0.9 GHz.

Modified pentagonal fractal antenna for ultra-wideband applications in communication systems

ABSTRACT Due to the recent expansion in the generations of the communications systems, it is utmost priority to transmit a large amount of data over a wideband frequency spectrum. For this single ultra-wideband (UWB) antennas are the prime choice as compared to the multiple narrow band antennas. A modified pentagonal fractal patch antenna with a modified ground plane covering ultra-wideband has been proposed. The antenna has a compact size of 25 mm × 25 mm × 1.6 mm with peak gain of 2.2 dB. The UWB coverage of the design is achieved by implementing modified co-planar ground, modified fractal geometry and coplanar feed. The proposed design possesses the significant resonance and radiation performance with very compact size on low-cost substrate while covering the whole UWB. Finally, the simulated resonating and radiation characteristics have been validated with the measured characteristics of the fabricated prototype and the results are quite promising.

Contactless current measurement for suspended overhead lines using a magnetic field sensor array

AbstractIn this study, a long‐distance non‐contact current measurement method is proposed based on the non‐contact sensor array measurement technology, combined with a new current algorithm. The sensor array is a vertical array composed of three three‐axis magnetic field (MF) sensors that is placed on the ground plane below the measured overhead line. The proposed current algorithm can optimize the geometry of the overhead line using the spatial MF values measured by the sensor array and then the three‐phase currents can be calculated. To improve the accuracy of current measurement, the spatial MF model in the algorithm considers the influence of cable sag. It enables a more accurate coupling matrix between the measured overhead line and the sensor array to be established. Additionally, the current algorithm architecture is designed using a composite algorithm to more optimally obtain the best three‐phase current values. A scale‐down overhead‐line measurement system is developed to test the proposed current measurement method. The results show whether a cable sag exists when the three‐phase currents are approximately balanced, with errors less than 2.0%. Moreover, it can be determined whether cable sag exists when the three‐phase currents are unbalanced, with less than 3.4% errors.

Two-Layer Inkjet-Printed Microwave Split-Ring Resonators for Detecting Analyte Binding to the Gold Surface.

This work focuses on demonstrating the working principle of inkjet-printed Au nanoparticle (NP) two-layer Gigahertz (2.6 GHz) microwave split-ring resonators (SRRs) as a novel platform for the detection of analytes on flexible substrates. In contrast to the standard fabrication of split-ring resonator biosensors using printed circuit board technology, which results in a seven-layer system, the resonators in this work were fabricated using a two-layer system. A ground plane is embedded in the SRR measurement setup. In this method, a microwave electromagnetic wave is coupled into the Au SRR via an inkjet-printed Cu-NP stripline that is photonically sintered. This coupling mechanism facilitates the detection of analytes by inducing resonance shifts in the SRR. In this study, the functionality of the printed sensors was demonstrated using two different Au functionalization processes, firstly, with HS-PEG7500-COOH, and, secondly, with protein G with an N-terminal cysteine residue. The sensing capabilities of the printed structures are shown by the attachment of biomolecules to the SRR and the measurement of the resulting resonance shift. The experiments show a clear shift of the resonance frequency in the range of 20-30 MHz for both approaches. These results demonstrate the functionality of the simplified printed two-layer microwave split-ring resonator for use as a biosensor.

Filtering wideband omnidirectional patch antenna with four operation states

A filtering wideband omnidirectional patch antenna with switchable dual bands is proposed to fulfil four operation states in this paper. Firstly, five resonant modes of the antenna are simultaneously and simply excited to enable the dual-band operation. Radiation nulls are generated beyond the bands, which improves the frequency selectivity and out-of-band suppression for the antenna. Furthermore, each of the bands could be easily and independently shut off to introduce three additional operating states by etching slots on the ground plane or/and inserting metallic rods at appropriate positions, with rejections of the suppressed bands larger than 10 dB. The radiation states show the characteristics of wide operation bands and broad stopbands. For verification, the prototypes are designed and fabricated. The simulated and measured results show good agreement.

DESIGN AND ANALYSIS OF MICROSTRIP ANTENNA FOR 5G APPLICATIONS

A new proposed antenna is presented in this article for 5G applications. The dimensions of this antenna are (32×32×0.8) mm³. The antenna that is suggested is built upon FR-4 epoxy dielectric substrate, with a loss tangent of 0.025 and relative permittivity of dielectric is 4.3 and, on the top layer of this substrate a polygon patch is etched with specific dimensions, also a ground plane on the bottom layer of the substrate is built. The patch of the antenna is fed from a microstrip feed line with a 50Ω characteristic impedance. The proposed antenna operates at 3.6 GHz as a resonance frequency with a bandwidth of (3.15 - 4.3) GHz, and gain (3.3) dBi at the operating frequency, these characteristics are suitable for 5G applications. To attain the targeted bandwidth and gain, distinct slots are carved onto both the patch and ground plane. The simulation outcomes are gathered using CST-MW 2020.

Design of a fractal triple-band reconfigurable filtering antenna for multiband applications

This letter constitutes a novel triple-band reconfigurable filtering antenna used for Bluetooth, WiMAX and WLAN applications. First, a compact triple-band reconfigurable filter is instigated which is composed of two pairs of Stepped Impedance Resonators (SIRs) and a pair of Uniform Impedance Resonators (UIRs). The SIRs are entrenched at the upper and lower half of feed lines operating at 2.4 and 5.4 GHz, respectively. A pair of UIRs operating at 3.5 GHz is folded and enclosed near the upper SIR. A shunt stub is tapped at the source-load feeding lines to upgrade the selectivity of the filter. The proposed filter uses four PIN diodes to initiate different reconfigurable multiband operations. A fractal antenna is implemented with a modified binary tree topology. The ground plane of the proposed antenna is reformed with a stub. The improved antenna structure enables three radiating bands with enhanced performance. Later, the designed filter is integrated into the antenna to implement the intended triple-band reconfigurable filtering antenna.

Spatially uncorrelated two port MIMO DRA using phase gradient PRS for dual directional pattern diversity

This study presents a system utilizing a cylindrical shape ceramic along with a suspended frequency selective surface (FSS), designed for multiple input multiple output (MIMO) applications with dual ports. The proposed antenna system showcases dual pattern diversity properties introducing spatially uncorrelated pattern. Key features of the structured radiator include the arrangement of cylindrical ceramic and the incorporation of an FSS. The alumina ceramic is purposefully placed on the upper part of the dielectric with a joint ground plane. These ceramics are stimulated using circular aperture. To reduce the far-field correlation, FSS with similar phase gradients are placed at the top of DRA at a certain distance. This arrangement yields two distinct radiation patterns from the two ports, ensuring a diverse radiation pattern for the antenna. The proposed technique yields significant improvements, surpassing 10 dB in isolation and achieving a 70% improvement in correlation values. The measured results validate the applicability of this antenna structure for WLAN access point applications within the 5.15–5.35 GHz frequency range.

Equivalent Circuit Analysis for Optimization of Ground plane in a Compact Co-axial Probe Fed Rectangular Microstrip Antenna

Equivalent Circuit Analysis for Optimization of Ground plane in a Compact Co-axial Probe Fed Rectangular Microstrip Antenna

Design of compact balanced filters with wide DM upper stopband and CM rejection band based on semi‐circular patch

AbstractA new design approach to achieve compact size and high common‐mode (CM) suppression of balanced filters is proposed with two back‐to‐back microstrip semi‐circular patch resonators. In feeding structures, metalized via holes are adopted to vertically feed patches by differential pairs. Then, TM11 mode is excited and TM31 mode can be rejected, resulting in wideband differential‐mode (DM) harmonic rejection. Besides, with a slotline etched in the common ground plane, desired coupling strength can be achieved for a target bandwidth. Meanwhile, by virtue of the stacked structure, source‐load coupling can be easily introduced to generate transmission zeros close to the passband. With theory guidance, two balanced filter prototypes centered at 2.4 GHz are designed. Simulation and measurement results both indicate that proposed balanced filters exhibit high DM and CM performances as well as a compact size about 0.26λg × 0.53λg.

Design and Performance Evaluation of a 6×6 MIMO Array with Partial Ground Plane for Sub-6 GHz Mobile Applications

Design and Performance Evaluation of a 6×6 MIMO Array with Partial Ground Plane for Sub-6 GHz Mobile Applications

Terahertz Uygulamaları için Grafen Malzemesine Dayalı Mikroşerit Bowtie Anten Tasarımı ve Optimizasyonu

The developments of the wireless communications technology, the Terahertz (THz) frequency band of the electromagnetic spectrum becomes promising and recently has the researchers’ attention to be utilized in several applications such as medical, indoor communications for personal networks, and the military applications. The main issues in this frequency band are the construction of a compact, high-performance antenna design; as in this frequency band, the material properties for conduction decrease as the frequency increases, and therefore the performance of the antenna diminishes. In this paper, we propose a graphene-based bowtie microstrip antenna, the performance of the graphene material in the THz frequency band is analysed based on the finite integration of the Computer Simulation Technology (CST) software. The graphene-based bowtie patch printed on a silicon dioxide substrate with a fully copper ground plane printed on its bottom. The proposed graphene plasmonic bowtie antenna covers a range of 0.1-10 THz band frequency with good gain in the range of 2-19 dBi in the mentioned band.

Linear Phased Metamaterial Incorporated Patch Antenna Array at 28 GHz for 5G Base Stations

This article presents a 1×6 linear phased antenna array implemented with metamaterial incorporated patch antennas for 5G base stations. The single element antenna was modelled on Rogers RT/duroid 5880 substrate in the dimensions of 7.8×7.8×0.254 mm3 with metamaterial incorporated partial ground plane and complementary metamaterial incorporated patch. This metamaterial incorporated antenna structure is resonating in 22.03–33.55 GHz at central frequency of 28 GHz with 40% impedance bandwidth with respect to the –10 dB return losses. With aim to design a radiating structure for 5G base stations and in order to enhance the gain, a six element phased array was developed using the abovementioned single element antenna with inter element spacing 7.8 mm between the adjacent antenna elements. In the analysis of this phased array, we observed acceptable diversity parameters (isolation, ECC, DG, CCL, and MEG) and presented beam steering capabilities by changing the phase difference between the adjacent ports. The proposed six element phased array antenna is capable to steer the beam to ±43.5° and capable to cover 5G NR n-257, n-258 and n-261 bands with significant gain and efficiency.

Electromagnetic radiation estimation at the ground plane near fifth‐generation base stations in China by using machine learning method

AbstractA novel method based on machine learning is proposed to estimate the electromagnetic radiation level at the ground plane near fifth‐generation (5G) base stations. The machine learning model was trained using data from various 5G base stations, enabling it to estimate the electric field intensity at any arbitrary radiation point when the base station provides service to different numbers of 5G terminals which are in different service modes. The inputs required for the model include the transmit power of the antenna, the antenna gain, the distance between the 5G base station and 5G terminals, terminal service modes, the number of 5G terminals and the environmental complexity around the 5G base station. Experimental results demonstrate the feasibility and effectiveness of the estimation method, with the mean absolute percentage error of the machine learning model being approximately 5.98%. This level of accuracy showcases the reliability of the approach. Moreover, the proposed method offers low costs when compared with on‐site measurements. The estimated results can be utilised to reduce test costs and provide valuable guidance for optimal site selection, thereby facilitating radio wave coverage or electromagnetic radiation regulation of 5G base stations.