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A novel windmill‐shaped metasurface (MTS) structure is firstly presented and applied to realise broadband antennas with stable radiation patterns. Different from conventional square MTS structure, the proposed windmill‐shaped MTS structure is formed by etching several triangular sawtooth slots instead of rectangular slots on the radiating square patch. Through the characteristic mode analysis, it can be found that the proposed MTS structure exhibits a much stable broadside radiation within a large bandwidth of 45.9%. Besides, the tapered edges resulted from the sawtooth slots can be regarded as smoother transitions, which would bring a better impedance matching. Based on above analysis, two antennas with different aperture sizes using the proposed windmill‐shaped MTS are well designed accordingly. Both antennas demonstrate the capability to achieve large impedance bandwidths over 40% and stable radiations (2‐dB gain bandwidth >33%). Compared with the conventional MTS‐based antenna, these proposed antennas improve the bandwidth and radiation performances effectively, showing great promises for modern wireless communication systems. [ABSTRACT FROM AUTHOR]

This article introduces a new planar multiband antenna inspired by metamaterials. The design incorporates a split-ring resonator (SRR) on a printed monopole antenna for ultra-wideband (UWB) communication, generating a new resonant frequency within the Industrial, Scientific, and Medical (ISM) frequency band. The effect of SRR-inspired slots was examined using characteristic mode analysis (CMA), revealing that the placement of the SRR on the antenna's radiating structure created multiple resonant modes. To improve impedance matching, the ground plane of the antenna was modified. The antenna was fed using a 50O microstrip line. The proposed antenna was simulated and fabricated on an inexpensive FR4 substrate with a thickness of 1.6 mm, a dielectric constant of 4.4, and dimensions of 38 x 40mm2. To validate the simulation results, the antenna parameters were measured. The results showed that the proposed antenna is capable of covering both the ISM frequency band (2.2{2.5 GHz) and UWB frequency band (3{26 GHz). This makes it suitable for various wireless communication applications requiring UWB and ISM frequencies, offering a promising solution. [ABSTRACT FROM AUTHOR]

We report on the realization of all-optical planar microlensing for exciton–polariton condensates in semiconductor microcavities. We utilize spatial light modulators to structure a nonresonant pumping beam into a plano–concave lens-shape focused onto the microcavity plane. When pumped above condensation threshold, the system effectively becomes a directional polariton antenna, generating an intense focused beam of coherent polaritons away from the pump region. The effects of pump intensity, which regulates the interplay between gain and blueshift of polaritons, as well as the geometry of the lens-shaped pump are studied, and a strategy to optimize the focusing of the condensate is proposed. Our work underpins the feasibility to guide nonlinear light in microcavities using nonresonant excitation schemes, offering perspectives on optically reprogramable on-chip polariton circuitry. [ABSTRACT FROM AUTHOR]

A miniaturized and low-profile planar antenna is a crucial part of any wireless communication system. To cover additional narrowband services and to reduce system complexity, antennas in portable devices should offer several operating bands. In this paper, we propose a coplanar-waveguide-fed (CPW-fed), flexible, and compact slotted patch frequency reconfigurable antenna with a compact size of 20 × 24 mm 2 . The designed antenna employs a low-cost Rogers 5880 substrate with a thickness of 0.127 mm. This choice of substrate ensures cost-effectiveness while preserving the desired performance of the antenna. The antenna radiates through five distinct frequency bands, including 5.58–6.25 GHz, 6.05–8.81 GHz, 8.79–9.7 GHz, 9.7–10.22 GHz, and 10.48–15 GHz, depending on the switch on/off condition, thereby enabling the antenna to span a broader range of frequencies for WLAN, C-UWB, sub-6 GHz, and X-band communications. The designed antenna is fabricated and tested in both the on and off states. The measured results closely match the simulated outcomes. [ABSTRACT FROM AUTHOR]

In this manuscript a stair case shaped planar monopole antenna for LoRa WAN application is proposed. The proposed unit element produces peak resonant at 2.41GHz with the operating bandwidth of 150MHz. The proposed structure has been constructed on FR4 substrate of thickness of 1.6mm with the dimension of 15 x24mm². The equivalent electrical dimension is 0.12 λo x 0.19 λo. A quad element MIMO structure has been constructed using the designed unit cell. The physical dimension of the MIMO array is 39 x 39 mm² and electrical equivalent is 0.31λo x 0.31 λo. The mutual coupling between the adjacent elements are <-18 dB. The measured Envelope Correlation Coefficient (ECC) of the antenna is < 0.05, gain is 1.17dBi and efficiency is 76.4%. [ABSTRACT FROM AUTHOR]

This paper illustrates a single antenna structure that simultaneously satisfies the antenna requirement for 5G cellular and global navigation satellite systems (GNSS). The antenna has a linearly polarised omnidirectional radiation for the newly defined 5G sub‐6 GHz cellular bands in the 617–5000 MHz frequency range. In contrast, a right‐hand circular polarisation (RHCP) with a hemispherical radiation pattern at the GNSS L1 has a frequency range of 1559–1606 MHz. This multi‐function antenna would provide a simplified product design and better space utilisation, particularly suitable for flat antenna modules and automotive. The primary concept involves employing a planar inverted F antenna structure to generate radiation modes for cellular bands and incorporate U‐slot on the top plate to generate the GNSS radiation modes. The design methodology utilises the characteristic mode analysis tool to tune the desired radiation characteristic mode at the intended frequency range for each function. The antenna was fabricated, and the performance was evaluated on a 1‐m ground plane. The GNSS RHCP gain measures 5 dBc at boresight, with an axial ratio below 2 dB across the L1 bands, while the cellular gain maintains an excellent return loss and omnidirectional radiation pattern performance across the cellular bands. [ABSTRACT FROM AUTHOR]

In this paper, a new planar printed quasi-Yagi antenna with compact size and wide bandwidth is presented for a multiple-input-multiple-output (MIMO) antenna system. Antenna element consists of a rectangular driven monopole, a strip director, and a coplanar ground shorted reflector. A planar rectangular monopole is used for the first time as a driven element instead of a dipole to avoid the implementation complexity of BALUN as it can be fed directly by an unbalanced coaxial feed. It has been shown that the antenna element has an impedance bandwidth (|S11| < −10 dB) of 60.5% ranging from 1.59 to 2.97 GHz. Based on this element, a four-element pattern diversity MIMO antenna is proposed. By utilizing the ground of one element as a reflector for the successive element, a compact size of 109 mm × 109 mm (0.54λ0 × 0.54λ0 at 1.5 GHz) has been obtained. Measured bandwidth of 65.9% (1.5–2.97 GHz) with minimum isolation of 13 dB has been achieved. The measured directional patterns and an average gain of 4 dBi, remain stable in the operating band with cross-polarization levels less than −25 dB. The envelope correlation coefficient and channel capacity loss show good diversity performance. [ABSTRACT FROM AUTHOR]

In this paper, a high gain circularly-polarized antenna array with a flat panel structure for low Earth orbit (LEO) satellite communication systems is proposed. This new CP structure can efficiently achieve high directivity and can easily be integrated with beamforming ICs (BFIC) when designing an antenna module, resulting in a good candidate for Ka-band satellite communications. Furthermore, the proposed FPAA can easily be extended to a larger scale array from a base unit in a 2 × 2 sub-array structure. Each sub-array is configured by four high-gain planar segmented antenna (PSA) elements with a sequentially rotating arrangement, where a single 4-channel BFIC can drive CP radiation. Unlike previously reported PSA elements that have limited CP performance, the proposed PSA-CP configuration adopts additional conductors and ground-via structures to further improve the CP gain, axial-ratio (AR), and cross-polarization (XPD) characteristics. To verify the performance of the proposed PSA-CP, a 2 × 2 left-hand circular polarization (LHCP) sub-array was fabricated at 28 GHz and tested with a BFIC. The measured 10-dB impedance and 3-dB AR bandwidths of the proposed 2 × 2 array were 13.92% and 12.5%, respectively. In addition, the measured peak gain was 15.2 dBic at 28.5 GHz with an XPD level of less than 15 dB. [ABSTRACT FROM AUTHOR]

A novel circularly polarised (CP) antenna design, termed differential mode (DM) and common mode (CM) design, is presented with equal‐amplitude in‐phase feed (EAIPF) in this article. At first, the CM and DM of the antenna are excited separately using the dual ports. Then, the CP antenna is obtained with EAIPF by adjusting the radiation amplitude of CM and DM, due to the orthogonality with a 90° phase difference for CM and DM. Finally, the obtained operational bandwidth of the presented antenna is 1.75–2.30 GHz (27.1%), with a reflection coefficient < −10 dB and axial ratio <3 dB. This CP antenna design eliminates the need to design 90° phase shifter as well as reduces the complexity of the feed structure of CP antennas, providing a novel idea for the design of CP antennas. [ABSTRACT FROM AUTHOR]

A broadband dual‐polarised antenna with L‐shaped strips for long‐term evolution (LTE)/5th generation mobile networks (5G) is proposed in this article. Based on the principle of multi‐mode resonance, wide bandwidth is achieved with L‐shaped strips and H‐shaped strips. The metal strips and dipoles are printed on the same substrate, which also contributes to antenna miniaturisation. The short pins are designed for impedance matching and improving isolation. The metal reflector is designed to control beamwidth and increase gain. A prototype was fabricated using an easy Printed Circuit Board technique to verify the proposed design. Low‐profile of 0.2λ0 (λ0 is the free‐space wavelength at the centre frequency) is achieved. The measured results show that the relative bandwidth is 74% (2.3–5.0 GHz) at Voltage Standing Wave Ratio <1.8 while the isolation is more than 24 dB covering the LTE/5G modern band. In addition, the in‐band average gain is 9 dBi. [ABSTRACT FROM AUTHOR]

Main aim behind this study is to utilize 3D printing technique for designing and fabrication of a flexible wideband Vivaldi antenna for the upcoming 5 G systems. Frequency bands starting from 24 up to 65 GHz are receiving particular attention as they have potential for both high data rate communications and high-resolution radar applications. A Vivaldi antenna is used for its very wideband properties and planar design. The radiating structure covers a bandwidth of 25–65 GHz for a match better than −10 dB and demonstrates reasonably high gain and efficiency performance. The simulated radiation efficiency of the antenna remains above 90% for the entire bandwidth. Hence, the main advantage of this approach is that wideband or switched transceivers for future 5 G communications can be integrated using this concept without the need of complex matching networks. [ABSTRACT FROM AUTHOR]

In this communication, a compact flower shaped printed antenna for ultra-wideband communication is proposed. The "flower-shaped" structure is capable of transmitting UWB-band signals. The designed antenna exhibits a return loss ranging from 2.3 to 11 GHz with an 8.7 GHz central frequency and has 130% relative bandwidth. The suggested design includes a patch in the shape of a flower with several slots fed by a microstrip line. Multiple slots have been designed for better resonances at lower modes. The antenna is constructed with an FR4 substrate, and a 50 Ω A-type connector feeds it. The optimum dimensions of the designed antenna are 12 × 16 × 1.6 cubic-millimeters and 0. 092λ ×.12λ × 0.012λ in lambda. The proposed structure also demonstrates stable radiation patterns across the operating bandwidth. The proposed radiator has a high gain of 2.67 dBi, and an efficiency of 85%. It is compact, lightweight, and easy to make. Therefore, it can be used for UWB applications. [ABSTRACT FROM AUTHOR]

In this article, we have performed a comprehensive investigation in the specialty of ultra-high frequency (UHF) printable antennas for partial discharge (PD) diagnostics. Due to the complex characteristics of PD signals in UHF range, selection of printable antenna becomes a major concern for PD diagnostics. The main contribution of this article is that we have provided a complete roadmap of selecting UHF printable antennas through relating antenna parameters with their practical significance on PD diagnostics in high-voltage equipment. We have highlighted 7 intrinsic parameters of UHF antennas and indicated their relationship with 7 extrinsic parameters of PD diagnostics performance. Following the extracted relationship, we have investigated on 8 different designing methods of UHF antennas. Based on the available results of recently reported works and their critical analyses, we have pointed out the existing challenges and indicated the future direction of UHF printable antennas for contactless partial discharge diagnostic systems.

We explore complementary cloaked antennas to improve their designs and to increase our understanding of the fundamental concepts of mutual coupling and cloaking effects by metasurface cloaks. We show that a cloaked planar dipole antenna (CPDA) and a cylindrically grounded cloaked slot antenna (CGCSA) placed in close proximity can be decoupled in the near field and cloaked in the far field of using planar metasurface cloaks; the antennas operate as if they were isolated. We perform an intensive parametric study to determine the optimal decoupling and cloaking regimes for both the CPDA and the CGCSA. The structures developed are in good agreement with previous findings regarding the cloaking effects, even when complementary antennas are in close proximity. Such analysis can also be applied to other types of complementary antennas placed close together that operate in neighboring frequency bands.

Interference and multipath are the most common issues in the wireless domain due to the coexistence of a large number of wireless nodes operating within the constraint spectrum. A compact planar antenna with five reconfigurable polarization states in three distinct operating bands is presented in this article. A square patch is enclosed by a square outer ring in the design, and these antennas are coupled-decoupled successively using switching diodes to excite three distinct operating bands. Coplanar microstrip lines are used to feed the orthogonal edges of the antenna. The diagonal corners of the inner and outer ring patches are truncated to realize dual circular polarization (CP) states with proper biasing. Switching diodes are placed at the etched corners to realize vertical (VP) and horizontal (HP) polarization. Both the orthogonal feed lines are activated simultaneously with identical phase and amplitude to realize 45° linear polarization. A low-profile, single-feed, compact prototype reconfigurable microstrip antenna (MSA) is finally designed, fabricated, and measured at 1.8 GHz, 2.4 GHz, and 5.8 GHz bands, respectively. Each operating band shows five distinct operating states. The simulation results for all fifteen states are found to be consistent with the measurement. [ABSTRACT FROM AUTHOR]

Designing modern antenna structures is a challenging endeavor. It is laborious and heavily reliant on engineering insight and experience, especially at the initial stages oriented towards the development of a suitable antenna architecture. Due to its interactive nature and hands-on procedures (mainly parametric studies) for validating the suitability of particular geometric setups, typical antenna development requires many weeks and significant involvement of a human expert. The same reasons only allow the designer to try out a very limited number of options in terms of antenna geometry arrangements. Automated topology development and dimension sizing is therefore of high interest, especially from an industry perspective where time-to-market and expert-related expenses are of paramount importance. This paper discusses a novel approach to unsupervised specification-driven design of planar antennas. The presented methodology capitalizes on a flexible and scalable antenna parameterization, which enables the realization of complex geometries while maintaining reasonably small parameter space dimensionality. A customized nature-inspired algorithm is employed to carry out space exploration and identification of a quasi-optimum antenna topology in a global sense. A fast gradient-based procedure is then incorporated to fine-tune antenna dimensions. The design framework works entirely in a black-box fashion with the only input being design specifications, and optional constraints, e.g., concerning the structure size. Numerous illustration case studies demonstrate the capability of the presented technique to generate unconventional antenna topologies of satisfactory performance using reasonable computational budgets, and with no human expert interaction necessary whatsoever. [ABSTRACT FROM AUTHOR]

This paper presents the study of an H- and dual C-shaped planar dipole antenna by adding and etching technique for the triple-band of drone operating frequencies. Tuning the frequency range was performed to cover the VOR standard of 108-118 MHz, GS standard of 328.6-335.4 MHz, and the DME standard of 962-1,231 MHz. The antenna structure was fabricated on a PCB of FR4 with a dielectric constant (εr) of 4.4 and thickness (h) of 1.6mm (material with low cost, compact size, and easy to use). The re ection coefficient (S11) results of the simulation and measurement were in good agreement, which demonstrated the bandwidth frequencies of resonance frequency at 112 MHz (106-118 MHz), 331.50 MHz (323-401 MHz), and 1,087.50MHz (920-1,301 MHz). The antenna gains were 1.73, 3.43, and 6.31 dBi, respectively, and the antenna radiation pattern was omnidirectional when it was used with H-plane. It was found in experiment that the proposed antenna could be installed in a drone with sending and receiving signals fittingly as desired. Furthermore, the proposed antenna is lightweight at just 0.4 kg, less than the original drone antenna (1.8 kg), and it does not require changing the antenna in each frequency range. [ABSTRACT FROM AUTHOR]

A novel wideband slot antenna with metasurface is presented. In order to achieve broadband, high-gain, and mechanical reconfigurable performance, a metasurface is adopted and combined with a new-type planar slot antenna The antenna and metasurface are designed on F4B substrate, and the overall dimension of the antenna is 1.48λ0×1.48λ0×0.2λ0 (λ0 is the free space wavelength at center frequency). Different from the traditional square metasurface, a structure with different properties in the x and y directions is utilized in the proposed antenna, which can be reconstructed by adjusting the relative position between the slot antenna and the metasurface. By introducing the metasurface, the maximum gain of the whole antenna is improved. The antenna works in two states with respect to the two locations of the metasurface. The impedance bandwidth of the proposed antenna in state A is from 5.49 to 9.40 GHz (52.5%), and the impedance bandwidth of the proposed antenna in state B is from 5.83 to 6.01 GHz (3%) and 7.05 to 9.62 GHz (30.8%). The gain of the whole antenna in both states is higher than that of the original slot antenna (without metasurface), and the maximum gain is 9.1 dBi. [ABSTRACT FROM AUTHOR]

In this letter, a compact magneto‐electric (ME) dipole antenna is designed and analyzed without compromising too much good performance of the ME dipole. In particular, the second‐order Minkowski‐like fractal structure is loaded on the planar electric dipole to effectively miniaturize the aperture size of the antenna. A prototype was fabricated and measured. The antenna volume is reduced by 24.6% when compared with the counterpart before the fractal. Meanwhile, the proposed antenna can achieve a bandwidth of 56% in terms of −10 dB ranging from 1.58 to 2.81 GHz. The radiation pattern of E‐ and H‐planes are basically identical. The cross‐polarization level is less than −25 dB, and the front‐to‐back ratio is larger than 14 dB. The maximum antenna gain can be up to 10.1 dBi. The measured results are in good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

In today's medicine, the celerity of the bio-assays analysis is crucial for the timely selection of the appropriate therapy and hence its effectiveness, especially in case of diseases characterized by the late onset of symptoms. In this paper, a lens-less fiber optics-based fluorescence sensor designed for the measurement of labeled bio-assays is presented and its potential for the early diagnosis of sepsis via C-reactive protein (CRP) detection is demonstrated. The sensor performance results from the combination of two key elements: a planar antenna that redirects fluorescence the marker emission and an automated fiber-based optical system for multi-spot analysis. First, the working principle of the device is demonstrated with a well-established antibody–antigen format (immunoglobulin IgG/anti-IgG assay), reporting more than one order of magnitude enhanced limit of detection (LOD) and limit of quantification (LOQ) for the planar antenna with respect to a standard glass substrate. The prototype is then tested against a sample mimicking a realistic case, prepared with commercially available human serum, showing a LOD and LOQ in the clinical range of interest (0.0015 μg/mL and 0.005 μg/mL, respectively) for the investigation of the sepsis biomarker CRP. These results validate the developed prototype as a simple and easy-to-operate device, compatible with standardized micro-well arrays, and potentially suitable for POC applications. [ABSTRACT FROM AUTHOR]

A distinctive low-profile 2 × 2 MIMO antenna system for Wi-Fi 7 applications is presented in this paper that is compact, easily manufactured and with excellent performance. Because of its compact size and good RF performance, the design can be placed in hidden locations for various applications such as the automotive field in the front side mirrors or front dashboard, and consumer products in laptops and internet wireless routers. The proposed design can cover the entire tri-bands of Wi-Fi 7 (2400-2495 MHz, 5150-5895 MHz, 5945-7125 MHz) using a loaded low-profile Planar Inverted-F Antenna (PIFA) with distinct dimensions and slots across its geometry. The element design and the MIMO system is simulated and a properly made prototype was fabricated to present the results in terms of reflection coefficients, current distribution, combined radiation patterns, passive isolation, ports efficiencies, and Envelope Correlation Coefficient (ECC). The design shows relatively good RF properties across the entire three bands, hence making it an attractive solution to be used for Wi-Fi 7 technology to satisfy the needs of larger omnidirectional coverage area, wider channel bandwidth, and better transmission rates with low interference. [ABSTRACT FROM AUTHOR]

An elliptical monopole planar antenna for ultra-wideband (UWB) with penta-band-notched characteristics is presented. The frequency band rejection at 3.7 GHz to 4.2 GHz for C-band satellite communication and 5.15 GHz to 5.35 GHz for lower wireless local area network (WLAN) is achieved by etching two elliptical split ring resonators (ESRRs) in the radiating patch. Dual notches at INSAT (4.5 GHz-4.7 GHz) and upper WLAN band (5.725 GHz-5.825 GHz) are created by special type of metamaterial, i.e., a two via double slot type EBG structure. Then, ITU band (7.95 GHz-8.55 GHz) is suppressed by adding a step impedance resonator (SIR) near the feed line. The proposed antenna is designed over a low cost FR4 material substrate, has a miniaturized size of 0.317×0.317×0.007?, and possesses the impedance bandwidth from 2.5 GHz to 11 GHz. The band notch behaviour of antenna at specific frequencies is explained by mathematical model and justified with numerically simulated surface current distribution and impedance plot. Constant gain with the peak value of 3 dB is measured for UWB except notch bands. Also, this antenna has application in S (1.97-2.69 GHz), LTE (450 MHz-3.8 GHz), C (3.4-7.025 GHz), X (7.25-8.44 GHz), Ku (10.7-14.5 GHz) bands. The proposed antenna structure is a promising candidate for wireless technology. [ABSTRACT FROM AUTHOR]

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 ( 1.036 λ o   × 1.001 λ o × 0.043 λ o where λ o 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. [ABSTRACT FROM AUTHOR]

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Spectrum sensing is an important aspect in cognitive radio (CR) networks as it involves the identification of unused frequency spectra, which saves both bandwidth and energy. The design of a compact super-wideband (SWB) multi-input multi-output (MIMO)/diversity antenna with triple-band-notched features is presented for spectrum sensing in CR systems. The MIMO antenna comprises four identical semi-elliptical-shaped monopole resonators, which are orthogonally positioned and excited individually via tapered coplanar waveguide feed lines. Also, a mirror-slot analogous to the radiator is etched in the ground conductor of each antenna element to achieve SWB characteristics. In order to avoid interference with the SWB, the antenna radiator is loaded with a staircase-shaped slit and a pair of concentric slits, arranged like a complementary split-ring resonator. The antenna resonates from 1.2 to 43 GHz, exhibiting a bandwidth ratio of 36:1. In the MIMO antenna, the antenna elements are located orthogonally, and the isolation > 18 dB and envelope correlation coefficient < 0.01 are realized in the resonating band. The antenna offers a peak gain of 4 dBi, and a sharp reduction in gain at notch frequencies (3.5 GHz, 5.5 GHz, and 8.5 GHz) is achieved. The size of the MIMO antenna is 52 mm × 52 mm. The proposed compact-size antenna features a high bandwidth ratio and straightforward design procedure, and can be simply integrated into contemporary RF equipment. The presented SWB MIMO antenna outperforms SWB antenna designs reported in the open literature, which featured one or two notched bands, whereas it has three notched bands. Also, the three notches in the SWB are achieved without the use of any filters, which simplifies the antenna development process. [ABSTRACT FROM AUTHOR]

A pentagon-shaped ultra-wideband (UWB) antenna with a high selective notch at the wireless local area network (WLAN) band is presented. An inverted L-shaped stub is incorporated with a pentagon-shaped metallic patch fabricated on an FR4 substrate. Also, a partial ground plane with a slot has been used to achieve UWB operation. Two structures are embedded into a patch to realize a rectangular notch. An electromagnetic band gap (EBG) structure is placed on the opposite side of the patch, and a rectangular complementary split ring resonator (RCSRR) is embedded in the patch. With the coupling of two structures, their notch bands are adjusted to achieve a rectangular notch. The bandwidth, upper and lower frequencies of the notch can be adjusted by varying dimensions of RCSRR and EBG. The measured and simulated results show S11 ≤ -10 dB for 3.1 GHz-12.5 GHz with a notch at the WLAN band from 5 GHz to 5.91 GHz. Also, the proposed design has a stable radiation pattern and gain with a peak value of 3.5 dB at 9.5 GHz and -6 dB at 5.1 GHz. The miniaturized size of the proposed design (21:5mm×27:5mm×1:6mm) with ultra-wide bandwidth makes it suitable for wireless applications. [ABSTRACT FROM AUTHOR]

A flexible, planar electrically small antenna (ESA) with omnidirectional radiation pattern is designed and fabricated for GPS and WLAN applications resonating at 1.5 GHz and 3.7 GHz. The design consists of a circular loop attached with 3 rectangular bars, and it is fed by a 50 feed line. The circular loop in the antenna provides impedance matching. Generally, these electrically small antennas have narrow bandwidth. Here the antenna is fabricated on a polyimide substrate having a thickness of 0.1 mm, r of 3.4 mm, and it occupies a size of 38mm × 34 mm. Electrically small antenna is designed at 1.5 GHz, 3.7 GHz, and the parameters that are measured are S11, VSWR, Ka values, quality factor, and radiation patterns. [ABSTRACT FROM AUTHOR]

In this paper, a noninvasive bone fracture monitoring system is developed using a planar monopole antenna. The proposed antenna provides an ultra-wideband response, and its overall size is 18 × 19 × 0.8 mm3. The proposed ultra-wideband monopole (UWM) antenna has a maximum measured gain of 3.77 dBi, and the maximum SAR value for an input power of 18 dBm is less than 1.6 (W/kg) (1 g). A bovine tibia is experimentally tested using a proposed UWM antenna to monitor the fracture recovery process and then further analysed using principle component and linear regression analysis. In addition, a microcontroller with a wireless communication module is developed to monitor the data in an Android application. The proposed system could be a promising approach for developing a portable, noninvasive monitoring device. [ABSTRACT FROM AUTHOR]

Higher performance, lower cost, and compact size antennas are important in today's wireless communication system where everything is connected. Many approaches are developed over the past twenty years to sustain suitable compact broadband antennas with efficient performance in many applications for easy integration and connection of devices, especially in the internet of things (IoT) technology and cognitive radio networks (CRNs). Broadband planar antennas, such as the Vivaldi tapered slot antenna (VTSA), are suitable for these applications due to their wide bandwidth, high gain, simple planner structure, low profile, lightweight, low fabrication cost, and easy integration with circuits. Although many approaches proposed for TSAs' compactness and performance enhancement, this work for the first time presents a comprehensive review of different types of ultrawide band (UWB) TSA designs focusing on the compactness and performance enhancement strategies pointing out to pros, cons, and practical applications for the last twenty years which are also addressed using extensive comparison tables. This comparison seeks to help both researchers and RF designers grasp the fundamentals of establishing effective steps for Vivaldi antenna design with high resilience by combining multiple strategies and exploiting their benefits while avoiding or mitigating their drawbacks. [ABSTRACT FROM AUTHOR]

The 5G communication system requires an antenna as a receiving device that has high performance including wide bandwidth and high gain. Microstrip antennas have advantages such as low cost, suitable for high frequencies and easy to integrate with other devices. One of the disadvantages of microstrip antennas is their narrow bandwidth and low gain. Therefore, microstrip antennas with wide bandwidth and high gain are especially needed to support 5G communication systems. This paper provides a solution by proposed a wide bandwidth and high gain microstrip antenna operating at a resonant frequency of 3.5 GHz for a 5G communication system. The proposed antenna was developed in four stages starting from a single element, a two-element series array, a 4-element series array and a 4×2-element planar series array. A series planar array technique is proposed to increase the gain and bandwidth of the microstrip antenna simultaneously. In this paper, simulations and measurements from the proposed antenna are displayed and compared comprehensively to show the performance improvement from each stage of the development of the proposed model. Based on the measurement results, the designed antenna has an impedance bandwidth (IBW) of 0.6 GHz and fractional bandwidth (FBW) of 17.14 % with a frequency range of 3.11–3.71 GHz and maximum gain of 12.2 dB at a resonant frequency of 3.5 GHz. The bandwidth and gain of the antennas increased by 205 % and 99.03 % compared to single element antennas, respectively. Therefore, the proposed antenna can be recommended to be used as a receiving antenna for 5G communication systems. [ABSTRACT FROM AUTHOR]

This work presents the design, fabrication, and measured results of a fully integrated miniature rectenna using a novel tunnel diode known as the Asymmetrical Spacer Layer Tunnel (ASPAT). The term rectenna is an abbreviation for a rectifying antenna, a device with a rectifier and antenna coexisting as a single design. The ASPAT is the centrepiece of the rectifier used for its strong temperature independence, zero bias, and high dynamic range. The antenna is designed to be impedance matched with the rectifier, eliminating the need for a matching network and saving valuable real estate on the gallium arsenide (GaAs) substrate. The antenna is fully integrated with the rectifier on a single chip, thus enabling antenna miniaturisation due to the high dielectric constant of GaAs and spiral design. This miniaturisation enables the design to be fabricated economically on a GaAs substrate whilst being comparable in size to a 15-gauge needle, thus unlocking applications in medical implants. The design presented here has a total die size of 4 × 1.2 mm2, with a maximum measured output voltage of 0.97 V and a 20 dBm single-tone 2.35 GHz signal transmitted 5 cm away from the rectenna. [ABSTRACT FROM AUTHOR]

A wideband quasi-Yagi antenna with symmetrical rectangular slots in the ground plane is studied. The feeding structure of the antenna is simplified, consisting of a microstrip transmission line and a short strip. The driver and director arms are designed as half on both sides of the substrate to improve pattern stability. The antenna's bandwidth is improved by symmetrically adding rectangular slots to the ground. The antenna works between 3 and 7.7 GHz with a gain that varies between 4.7 to 7.4 dBi, a bandwidth of 87.8 % , and an efficiency of more than 90 %. The antenna has a very compact size of 0.42 λ L × 0.42 λ L ( λ L is the wavelength for the lowest operating frequency). The simulation and measurement results are in good agreement. The antenna has highly stable end-fire radiation within its operating frequency and can be used for wideband wireless communication systems. [ABSTRACT FROM AUTHOR]

In this paper, a miniaturized quarter‐mode substrate integrated waveguide (QMSIW)‐based self‐multiplexing antenna is designed to achieve high isolation in terms of small‐frequency ratios. First, the cross‐shaped slot is introduced to split the antenna into four parts with different dimensions, equivalent to four QMSIWs with different frequencies. By adjusting the slot position parameters, the QMSIW can be adjusted independently. Second, the antenna placement is optimized by adjusting the position of the slot and applying the frequency spacing technique. The designed antenna operates in four similar frequency bands (4.8, 5.15, 5.5, and 5.8 GHz). The isolation of adjacent units is more remarkable than 35.1 dB, while the isolation of relative units is more excellent than 22.7 dB. The structure of the proposed planar antenna is simple and suitable for handheld microwave devices. [ABSTRACT FROM AUTHOR]

In this paper, a novel low profile planar inverted-F antenna (PIFA) with high gain and low specific absorption rate (SAR) using a miniaturized artificial magnetic conductor (AMC) is investigated. The performance of the PIFA antenna is analyzed with AMC to understand the contribution of AMC. The gain enhancement of the PIFA antenna is achieved by applying AMC below the antenna. Furthermore, the placement of AMC also reduces the SAR of the antenna and improves the antenna front-to-back ratio (FBR). The proposed antenna when measured has an impedance bandwidth of 4.8–6.7 GHz (33% with center frequency at 5.75 GHz) which is suitable for Wireless Local Area Network (WLAN), satellite uplink C-band, and sub-6 5G applications with the maximum gain of 7.6 dBi. The performance of the proposed antenna is analyzed by full-wave commercial electromagnetic software and verified by measurements. [ABSTRACT FROM AUTHOR]

The aim of this experimental research is to present the advantages of advanced methods for digital transformation of objects in order to create accurate engineering models of aerospace objects and radio engineering devices. One of the scientifically applied contributions is expressed in the proposed algorithm for engineering design of a pyramidal horn antenna based on simulation data, realized by 3D modeling techniques for digitalization. The generated results illustrate the correct selection of software products due to their compatibility and capabilities. [ABSTRACT FROM AUTHOR]

High gains with highly efficient Circularly Polarized (CP) microstrip planar and conformal cylindrical patch antennas are designed for the Industrial Scientific Medical (ISM) band. A dumbbell-shaped slot is incorporated in the centre of an irregular hexagonal radiator to produce circular polarisation with high gain. The simulation results yielded the impedance mismatch loss (S11) bandwidth of 78.8 MHz and axial ratio bandwidth (AR) of 10.3 MHz for the planar patch. In this study, the values of the impedance mismatch loss and AR bandwidths of the conformal cylindrical patch antenna were obtained as 46.2 MHz and 10.6 MHz, respectively, indicating that the return loss bandwidth in this case decreased by almost 42% while the axial ratio bandwidth remained almost the same. The axial ratio of the beam-width for Phi = 0° was 83° and for planar patch and conformal patch, it was 61°. Consequently, in the planar patch, the gain was obtained as 8.79 dBic with 96.33% efficiency while in the conformal patch, the gain was measured as 4.16 dBic with 95% efficiency. [ABSTRACT FROM AUTHOR]

A directional monopole antenna using a planar lossy magnetic (PLM) surface is proposed in this paper. When a monopole antenna is designed vertically on the ground plane composed of a perfect electric conductor (PEC) and a perfect magnetic conductor (PMC), the surface current on the ground plane cannot flow on the PMC and only flows in one direction on the PEC. Therefore, the electromagnetic (EM) wave of such a monopole antenna can radiate in the direction perpendicular to the ground. Alternatively, a PLM surface such as a ferrite sheet with a high relative permeability was employed to achieve EM properties similar to the PMC. To verify the feasibility of the proposed antenna, a ferrite sheet with a relative permeability of 20 and a magnetic loss tangent of 10 at 2 GHz was utilized to implement the half PMC ground plane, and the monopole antenna was bent for miniaturization. The measured peak gain and the -10 dB bandwidth was about 1.3 dBi and 23% at the resonant frequency, respectively. [ABSTRACT FROM AUTHOR]

This work presents an integrated planar five-element antennas system for cognitive radio (CR) applications.The proposed system is composed a UWB antenna for sensing the radio spectrum and four different NB antennas for conducting the communication tasks. The overall antenna system is printed on FR-4 substrate of 50 mm × 50 mm × 1.6 mm dimension. The UWB antenna-coupled at port 5 (P5) is designed for sensing the 3.1 GHz to 10.6 GHz un-licensed UWB band. The first NB antenna attached to port 1(P1) covers 5 GHz to 11.4 GHz wideband frequency, whereas the paired NB antennas located at port 2 and port 3 (P2 & P3) consists of two similar antennas to achieve MIMO operation and provides 3.05 GHz to 3.75 GHz and 4.9 GHz to 6.1 GHz dual-band operation. The last NB antenna accessible at port 4 (P4) operates in dual-band frequencies of 3.7 GHz to 4.92 GHz and 8.3 GHz to 11.3 GHz. These attained resonant bands cover applications, notably Wi-MAX 3.5 GHz, Upper WLAN, sub 6 GHz 5G, and X-bands in the full UWB spectrum. The minimum isolation among all UWB and NB antennas is 16 dB over the working bands. The MIMO performances of the port 2 and port 3 antenna pairs have been computed considering the envelope correlation coefficient and mean effective gain, and found within their practical limits. The measured results are validated and show a good matching with the simulated ones. The low profile and planar features of the suggested antenna make it a possible choice to be assimilated within small wireless devices applicable in CR communication. [ABSTRACT FROM AUTHOR]

In this paper, the fundamental principles of UWB and CRS technologies have been presented, and the approach of these systems in recent research focuses on the efficient use of RF resources. UWB systems are an alternative with great scientific support for identifying spectral gaps and allocating RF dynamics in the CRS. Microstrip planar antennas for UWB and CRS systems have been mentioned as practical alternatives for implementing the radio interfaces of these complex systems, as will be proposed in this work. The need for the most efficient use of available spectral resources is the starting point for understanding the growing interest in emerging mobile communications systems. The coexistence of several wireless systems in a limited frequency band and the increasing demand for applications that require high transmission rates have needed new strategies for managing and allocating RF resources. In this sense, UWB and CRS technologies have been presented as promising improvements in the use of radiofrequency resources. This paper presents the fundamental principles of UWB and CRS technologies, emphasizing microstrip planar antennas, whose application has been successfully proven in recent research over the last few decades, as will be exposed in this work. [ABSTRACT FROM AUTHOR]

We present a specific subwavelength-cavity high-gain circularly polarized ultra-thin antenna made of planar metamaterials. The antenna is designed to operate at 2.80 GHz with a fixed thickness of approximately 1/6 of the operating wavelength in free space. The asymmetric unit cells of the metamaterial antenna exhibit two characteristics, namely, negative permeability and polarization selection. A linear-polarization micro-strip patch, which can realize circular polarization without a complicated feeding network, is embedded in the cavity as a feed. The circular polarization mode of the antenna can be changed by simply rotating the planar metamaterial horizontally. Simulations and experiments conducted on this antenna yielded results that are in good agreement with each other. This new subwavelength planar antenna can have potentially important applications in communication, early warning systems, and radio observation. [ABSTRACT FROM AUTHOR]

This paper proposes a compact planar Wi-Fi antenna with optimized radiation patterns for small uncrewed aerial vehicle (UAV) applications in both urban and open areas. It is suitable for mounting on the outermost side of the non-metallic wing of small UAVs. It has small dimensions of 16.5 mm (L) by 30.3 mm (W) by 1.6 mm (h), and the measured results of its prototype are in agreement with simulated data. Its impedance bandwidths over the two frequency ranges are 2.11 to 2.58 GHz and 5.06 to 7.5 GHz ( S 11 ≤ - 10   d B ). At 5.8 GHz, it has stronger radiation below the small UAV to reduce interference from rare-use directions. Its maximum radiations, the directions of the maximum radiation in each elevation plane, are below the UAV and between 14° and 29° from the horizontal plane. At 2.4 GHz, it has quasi-omnidirectional radiation to ensure a stable link in all directions, and its maximum radiations are near the horizontal plane. The optimized radiation patterns at 5.8 and 2.4 GHz can provide more antenna gain when the small UAV flies farther in urban and open areas, respectively. In addition, it has good vertically polarized radiation for long-distance applications. [ABSTRACT FROM AUTHOR]

This communication offers a low-cost concaveshaped rectangular stub-loaded monopole 2x2 multi input multi output (MIMO) planar antenna for sub6GHz mid-band (N-78) and wideband wireless Wi-MAX applications. Two symmetrical reduced grounds are utilized to enhance the fractional bandwidth (FBW) and isolation factor. MIMO is further parasitically loaded with two rectangular stubs to tune the antenna close to the design frequency at 3.6GHz. The antenna possessed an Omni-directional radiation pattern (Peak gain of 3.38dBi and maximum radiation efficiency 92.82%) with a measured reflection coefficient (S11) value lower than -10dB for a bandwidth 3.285-3.87GHz and excellent measured isolation coefficient (S12) lower than -20dB using parasitic rectangular stubs and spatial distance approximately μg/2. All diversity parameters (CCL, DG, ECC, MEG, TARC, VSWR-MIMO, group delay) of this antenna are well below threshold values. The 2-port MIMO values of CCL<0.4bit/sec/Hz ensure a high data rate and DG close to 10dB confirms better reliability. The measured results show good closeness with simulated parametric graphs. The wideband impedance bandwidth is 14.87% (3.3-3.83GHz) for TARC lower than -10dB. That covers Sub-6GHz (N-78) mid-band (3.3-3.8GHz) and Wi-MAX (3.3-3.6GHz) applications. The RLC electrical equivalent circuit of the MIMO antenna is also discussed in this article. [ABSTRACT FROM AUTHOR]

Millimeter wave antennas have the advantage of high directivity, miniaturization, high resolution and data transfer speed, wide bandwidth, and lower latency. In this work, a millimeter wave planar array antenna (PAA) with the characteristics of wideband and low sidelobes, which consists of eight identical linear array antenna (LAA) based on Ti3C2 MXene, is designed and fabricated. It is the first time that MXene antennas are proposed for a 5G millimeter wave antenna application. MXene PAA has a high realized gain of 22.22 dBi and a −10 dB impedance bandwidth of measurement covering the range from 24 GHz to 28 GHz, including the 5G FR2—n258 frequency band. With Chebyshev current distribution, the MXene PAA has a half-power beam width of 10.2° and 10.8° in the xoz-plane and yoz-plane radiation patterns with the sidelobes levels below −20 dB, respectively. Therefore, MXene PAA is suitable for 5G mobile communication applications. [ABSTRACT FROM AUTHOR]

A miniaturized enhanced isolation 8-unit MIMO antenna for smartphones is proposed in this paper. The units are planar inverted-F antennas with the same structure, and we use the slotting method and shorted probe to miniaturize them. The size of every unit is 14 × 6 mm2 (0.149 × 0.064λ2). We insert an L-shaped decoupling element into the middle of adjacent radiating elements and connect the decoupling element to the GND. Note that the decoupling elements are on the outer side of the substrate, and the radiating elements are on the inner side of the substrate. Finally, a prototype is fabricated and measured. The measured results show that the bandwidth of the MIMO antenna is from 3.0 GHz to 5.3 GHz (55.4%), which fully supports the n77, n78, and n79 in the 5G nR frequency band and the 4G LTE 42 frequency band (S11 less than −6 dB). The measured isolation of the MIMO antenna is greater than 25 dB by using the decoupling method in this paper. The envelope correlation coefficient of the proposed MIMO antenna is less than 0.08, its radiation efficiency is greater than 50%, and its gain is between 4.2 and 5.3 dBi in the whole operating frequency band. [ABSTRACT FROM AUTHOR]

In this paper, a printed monopole antenna with high-gain and dual-band characteristics for applications in wireless local area networks and the internet of things sensor networks is presented. The proposed antenna consists of a rectangular patch with multiple matching stubs surrounded to improve the impedance bandwidth of the antenna. The antenna incorporates a cross-plate structure which is seated at the base of the monopole antenna. The cross-plate consist of metallic plates aligned perpendicularly which enhances the radiations from the edges of the planar monopole to maintain uniform omnidirectional radiation patterns within the antenna's operating band. Furthermore, a layer of frequency selective surface (FSS) unit cells and a top-hat structure is added to the antenna design. The FSS layer consist of three unit cells printed at the back side of the antenna. The top-hat structure is placed on top of the monopole antenna and comprises of three planar metallic structures arranged in a hat-like configuration. The coupling of both the FSS layer and the top-hat structure presents a large aperture to increase the directivity of the monopole antenna. Thus, the proposed antenna structure realizes a high gain without compromising the omnidirectional radiation patterns within the antenna's operating band. A prototype of the proposed antenna is fabricated where good agreement is achieved between the measured and full-wave simulation results. The antenna achieves an impedance bandwidth |S11| < − 10 dB and VSWR ≤ 2 for the L and S band at 1.6–2.1 GHz and 2.4–2.85 GHz, respectively. Furthermore, a radiation efficiency of 94.2% and 89.7% is realized at 1.7 and 2.5 GHz, respectively. The proposed antenna attains a measured average gain of 5.2 dBi and 6.1 dBi at the L and S band, respectively. [ABSTRACT FROM AUTHOR]

In this work a compact size capacitive load dual band planar inverted-F implant antenna is presented. The suggested antenna is modeled on RO3010 substrate that has a thickness of 2 mm, dielectric constant of 10.2, and tangent loss of 0.0023 to operate at both the Medical Implant Communications Services (MICS) and Industrial, Scientific, and Medical (ISM) bands. A capacitive load is inserted between the patch and the ground plane to get a dual band and compact size implant antenna. The idea behind the capacitive load is to support a simple structure with a dual band and compact size in addition to get a gain enhancement. The antenna size is 20 × 12 × 2 mm3. The antenna designed in this work operates at 402 MHz with a return loss of − 23.23 dB over a frequency band [397.15–409.4 MHz] for MICS band and operates at 2.42 GHz with a return loss of − 20 dB over a frequency band [2.37–3 GHz] for ISM band. The simulated gain is − 27.52dBi at 402 MHz for MICS band and − 1.85dBi at 2.42 GHz for ISM band. The proposed antenna has a good performance inside three-layered tissue model. The Computer Simulation Technologies (CST) Microwave studio is used to model and simulate the proposed antenna. [ABSTRACT FROM AUTHOR]

5G NR (new radio) introduces the concept of massive MIMO (multiple-input multiple-output) technology, in which a larger number of antenna arrays are installed on the transceiver. Due to the increased number of antenna elements allocated close to each other (approximately at a distance of half a wavelength), mutual coupling becomes a serious problem leading to performance degradation of the MIMO communication system. In this communication, two different configurations of closely spaced antenna array elements are studied. In order to reduce the mutual coupling, a combination of a metamaterial-based frequency-selective surface (FSS), a metallic strip, and a slot element in the ground plane is examined. It is found that the proposed technique significantly suppresses mutual coupling from −12 dB to −25 dB. Both designs are fabricated and experimentally validated. The simulation results are in good agreement with the measurements. The proposed mutual coupling reduction technique may be suitable for massive MIMO systems in fifth-generation (5G) new radio applications. [ABSTRACT FROM AUTHOR]

This paper presents a low-profile wideband, dual-polarized patch antenna using differential-paired, multi-mode arms. By employing the arrow-shaped, differential-paired arms, three modes of them are excited simultaneously, leading to a broad bandwidth. The shorting pins are uniquely inserted at the wings of the arms to obtain stable radiation patterns. Then, two pairs of arms are structured like the dipoles and a dual-polarized antenna is designed. In addition, by employing coplanar coupling feeding structures, a good wideband impedance matching is also achieved without increasing the height. For demonstration, a wideband dual-polarized patch antenna is designed and measured. Benefitting from the advantages of the multi-mode patch and symmetrical structure as a dipole antenna, the proposed dual-polarized antenna operates between 2.10–3.95 GHz, possessing a 10-dB impedance bandwidth of 61%, a profile of 0.1λ0, an average gain of 7.31 dBi, and stable radiation patterns. [ABSTRACT FROM AUTHOR]