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The present work introduces a novel low‐profile antenna for UWB applications through the use of a frequency‐selective surface (FSS). The FSS reflector uses a 7 × 7 array with a unit cell of 12.4 × 12.4 mm. By incorporating this periodic structure, the antenna's peak gain reaches 11 dBi, covering a UWB frequency range from 3.01 GHz to 13.5 GHz. Both FSS and UWB antennae are printed on the same type of substrate (FR4‐epoxy). The gap between the FSS layer and antenna is a half wavelength (18 mm) to obtain the best performance. The fabricated optimized antenna prototype shows a reasonable accord between numerical and experimental results. These results are compared to the existing literature designs. Overall, the proposed antenna system has reduced complexity and size, while offering a very wide bandwidth and high gain, making it a good candidate for imminent wideband and high‐gain wireless communication systems. [ABSTRACT FROM AUTHOR]

Assembling polarization conversion metasurface (PCM) and a simple patch antenna to realize a circularly polarized (CP) antenna with over 10% fractional bandwidth (BW) is a challenging task. A kind of PCM composed of S‐ring and grating structure that converts linearly polarized (LP) wave into CP wave in a broadband frequency from 8.74 to 12 GHz can address the challenge. The universality of the PCM in realizing antenna polarization conversion is verified by using a standard LP horn antenna. Then, we design a broadband LP rectangular patch antenna to demonstrate that the present PCM can be integrated with small antenna devices to achieve CP antenna. A broadband CP patch antenna with a 12.4% −10 dB BW and 11.3% 3 dB axial ratioBW is obtained. The antenna gain reaches 8.1 dB with the enhancement gain of 4.1 dB. The findings are very attractive for wireless communication, radar monitoring, and satellite systems because the proposed antenna has excellent broadband CP performances, simple structure, and easy fabrication. [ABSTRACT FROM AUTHOR]

This article proposes a Ka‐band substrate integrated waveguide (SIW) quasi‐Yagi array antenna with the advantages of thinness, compactness, wide bandwidth, and higher gain. Analyzing the microstrip‐to‐SIW transition structure to confirm that the designed structure provides the best performance, the optimum reflectance coefficient bandwidth can be obtained. With the optimized rectangular etched slot structure at the antenna end, the impedance matching can be tuned to improve the bandwidth. The designed array antenna is fabricated and measured for verification. The substrate is based on Al2O3 ceramic and the antenna size is 23.3 mm × $\times $ 13 mm × $\times $ 0.5 mm. The measurement results indicate that the antenna achieves an impedance bandwidth of 13.59% below −10dB, with an average gain of approximately 7 dBi and a peak gain of 7.4 dBi in 28.1–32.2 GHz. Therefore, the 1*2 antenna proposed in this paper has the advantages of compact and planar structure, easy fabrication, and easy integration into RF circuits, which is very suitable for Ka‐Band applications. [ABSTRACT FROM AUTHOR]

A stacked dual‐band antenna system based on frequency selective surface (FSS) is proposed in this paper. The system consists of lower band (LB) and higher band (HB) antenna elements with a frequency ratio of 2.5. FSS is introduced between LB and HB elements, which can fully reflect LB wave and transmit HB wave without reflection. LB and HB antenna arrays can be designed independently and combined with only a few screws, allowing for flexible combination of different arrays according to different needs. The stacked scheme can avoid the generation of grating lobes caused by excessive spacing of HB elements. Two different arrays were analyzed, simulated, and measured to validate the excellent features of the proposed scheme, such as easy to combine, stable radiation patterns, and lower mutual interference for LB and HB elements, respectively. The proposed system can be a promising candidate for dual‐band wireless communication with large frequency ratio. [ABSTRACT FROM AUTHOR]

A novel Quasi‐Yagi‐Uda antenna on a flexible material is designed and demonstrated in this paper. The antenna is developed on an ultra‐thin polyimide substrate to support dual‐frequency bands centered at 3.8 and 5.2 GHz for 5G and WiFi‐enabled wireless communications. The proposed Quasi‐Yagi‐Uda has a twin‐F‐shaped driven element which is excited using a microstrip line feed. The arms of the driven element are suitably designed to meet the frequency specifications of the proposed antenna. The design of the antenna is carried out using Computer Simulation Technology Microwave Studio while the antenna optimization is performed using the Fire‐Fly algorithm. The optimum geometrical details of the proposed antenna are obtained with a higher rate of convergence. The proposed dual‐band antenna provides 205 and 195 MHz bandwidth in both frequency bands guaranteeing high‐speed wireless communications in the 5G domain. The Quasi‐Yagi‐Uda provides a gain greater than 4.5 dBi in both operating bands with an efficiency greater than 80%. The prototype antenna optimized using the Fire‐Fly algorithm is fabricated and the simulation results are validated. [ABSTRACT FROM AUTHOR]

A novel reflect‐transmit‐array antenna is proposed in this paper, in which a single‐layer heteropolarized element with a thickness of 0.1 λ0 ${\lambda }_{0}$ at 11 GHz, consisting of only two layers of metal patches printed on a dielectric substrate and six metal vias, can integrate reflection and transmission modes in the same frequency band by reasonably distributing the positions of the reflection and transmission parts in the element. We designed, fabricated, and measured the reflect‐transmit‐array antenna with an aperture of 501.2 mm2. At 11 GHz, the maximum gain of reflection is 17.7 dB, and the peak gain of transmission is 20.4 dB, indicating that this scheme has good application prospects in bidirectional wireless communication. [ABSTRACT FROM AUTHOR]

This study describes an array antenna that allows for reconfiguration of the three significant antenna properties, that is, radiation pattern, half‐power beamwidth (HPBW), and single and bi‐directional beam. A reconfigurable reflecting surface (RRS) has been designed and incorporated with the array antenna on the top and bottom. The RRS works to reflect or pass the incident electromagnetic wave. It enables us to reconfigure from single to multibeam radiation in the ±z direction. It also provides two levels of HPBW, that is, 49.6° and 95°. Eventually, the same three sets of antennae have been stacked and rotated with a 60° angle to achieve the radiation pattern reconfiguration in the entire azimuth plane. It conforms to reconfigure all three antenna properties in six directions at an equal interval of 60° angle. The achieved maximum gain in a narrow beam is 9.56 dBi. The proposed reconfigurable antenna array can be used in modern wireless communication applications. [ABSTRACT FROM AUTHOR]

This paper presents a novel wideband circularly polarized antenna that is fed by substrate‐integrated waveguide. Based on the design of placing a pair of chamfered semicircular patches above a slot, a π ${\rm{\pi }}$‐shaped radiator is introduced between the semicircular patches. Multiple resonance points are generated by the combination of the entire radiating structure and a dumbbell‐shaped slot, resulting in improved impedance bandwidth and axial ratio (AR) bandwidth. The proposed element exhibits a wide impedance bandwidth of 50.5% (24.5–41.1 GHz) and an AR bandwidth of 44.2% (25.1–39.3 GHz) with a 44.2% overlapped bandwidth. Then, a 4 × 4 antenna array adopting the sequential rotation technique is constructed. The measured results demonstrate that a 40.6% overlapped bandwidth and a peak gain of 19.1 dBic are achieved. The proposed antenna array shows excellent performance, making it a good candidate for applications in millimeter‐wave wireless communication systems. [ABSTRACT FROM AUTHOR]

This paper proposes a high aperture efficiency (AE) small size tensor holographic impedance metasurface (THIMS), which has the ability to create circular polarized (CP) high purity orbital angular momentum (OAM) multi‐beams with flexibly independent control of the individual beam direction, polarization and OAM mode. The tensor unit cell is a cross‐slotted circular patch. We design a THIMS at 14.6 GHz for dual CP OAM beams: Beam‐I (LHCP, l = 1, θ1 = 30°, φ1 = 0°), Beam‐II (RHCP, l = −1, θ2 = 30°, φ2 = 180°). The developed tensor dual CP THIMS has the following advantages: high purity in xoy plane at z = 9.73 λ (λ wavelength, measured purity 88.4% for Beam‐I, and 93.5% for Beam‐II), high AE 25.1%, and small size 5.986 λ × 5.986 λ × 0.0618 λ. The calculated, simulated and measured results agree well. The generated dual CP OAM beams have potential applications for high‐capacity wireless communication, radar high resolution imaging, and rotation velocity measurement. [ABSTRACT FROM AUTHOR]

In the advancing field of 5G technologies, particularly at the 60 GHz band, dielectric resonator antennas (DRAs) stand out for their low conduction loss and high radiation efficiency. However, the traditional design process for DRAs, predominantly reliant on intuitive reasoning and trial‐and‐error methods, is notably inefficient and resource‐intensive. Addressing this critical challenge, our research introduces a pioneering approach: a generative adversarial network (GAN)‐based model specifically tailored for automating DRA structure design. This novel model represents the first of its kind in the domain, marking a significant departure from conventional methods. Our GAN model uniquely integrates a simulator for DRA modeling and a generator for DRA structure design, streamlining the design process. To effectively train this model, we created a simulated data set comprising pattern–annotation pairs of geometric shapes and S11 parameters. This data set enabled the GAN to capture the intrinsic principles underlying DRA design. The practical impact of our model is profound; it significantly expedites the DRA design process, aligning it more closely with specific user requirements while conserving valuable time and resources. This breakthrough approach not only enhances the efficiency of DRA design but also sets a new standard in antenna technology development for future wireless communications. [ABSTRACT FROM AUTHOR]

Securing internal wireless communication of a corporate network from external eavesdropping requires electromagnetic (EM) shielding of the whole building, which may also block useful communication bands, such as mobile phone, radio, security, and television networks. Frequency selective surfaces provide selective spatial filtering of EM signals. A dual concentric modified square loop of unit‐cell dimension 26.16×26.16 mm2 $26.16\times 26.16 {\mathrm{mm}}^{2}$, fabricated on a window blinds material with dielectric constant 1.63 is presented for shielding indoor wireless network. The design resonates at WiFi and Bluetooth frequencies of 2.4 and 5 GHz and offers a measured suppression of at least −45 dB at both the frequency bands. Simulation and experimental results have been presented which exhibit stable and polarization insensitive responses in both, transverse electric and transverse magnetic modes, as well as angular stability for oblique incident angles up to 60°. The proposed Frequency Selective Window Blinds provide on‐demand, passive EM shielding and are easy to develop, install, and use. [ABSTRACT FROM AUTHOR]

A novel conformal quasi‐yagi antenna and its Multiple Input Multiple Output (MIMO) implementations for wireless body area networks (WBAN) application is reported in this letter. The antenna is developed on a 0.05 mm thin polyimide substrate making the antenna more flexible and conformal. The footprint of the proposed antenna is 35 × 35 mm with a dual dipole arm‐like structure making it resonant at 2.45 and 3.5 GHz covering the industrial scientific and medical and 5G bands for WBAN communications. The antenna is excited using a microstrip‐to‐slotline termination suitably terminated by a circular patch to realize the impedance matching. The ground plane is shaped to maintain good isolation between neighboring antennas during the eight‐element MIMO antenna development. The MIMO antennas are arranged circularly to achieve good antenna coverage along the azimuth directions. The antenna generates a tangential radiation pattern to the plane of the human body making it suitable for on‐body wireless communications. The proposed antenna offers a rotatable radiation pattern by appropriately choosing the antenna port of excitation. The proposed MIMO antenna offers an average gain of 4.5 and 5.2 dBi at 2.45 and 3.5 GHz, respectively. The MIMO antenna parameters are evaluated and presented. The calculated MIMO parameters are within the acceptable limits. Thus, the flexible nature with rotatable directional radiation patterns has made this antenna an attractive choice for on‐body communications in WBAN. [ABSTRACT FROM AUTHOR]

The antennas that share radiators with solar cells are applicable to collect energy and integrate radio frequency functions. In this paper, a solar cell integrated multiband antenna is proposed on the basis of Vivaldi antenna structure. Unlike prior research, it has the capacity to reconfigure working frequencies and radiation performance of the antenna through optical control of the solar cell. The purpose of reconfiguration is achieved by means of two switching diodes placed between the differential Vivaldi radiator and conducted via biasing from the solar cell. The integrated solar cell functions both as part of the radiator and as the biasing source for switching diodes. According to the simulation and measurement results, the antenna performs consistently at around 5 GHz, while the radiation performance can be reconfigured at 1.16 and 3 GHz under illumination. In this way, the proposed antenna can fulfill various functions such as green energy collection, wireless communication, and light detection, which makes it applicable in the Internet of Things for low‐power wireless sensor terminal. [ABSTRACT FROM AUTHOR]

The impressive growth in present‐day wireless communication systems demands compact, low‐power, cost‐effective, planar multiband microwave devices to increase the speed of communication and reduce hardware requirements, which subsequently reduce the power requirement of the system. Accordingly, this article aims to design a multiband microstrip bandpass filter with asymmetric dual‐band response based on metacell. The proposed filter is designed for wide and narrow dual‐band responses with fractional bandwidths of 72% and 2.6%, respectively. For the first time in this article, a new application of metacell in the design of dual‐band filters is discussed. A folded asymmetric step‐impedance resonator and a novel metacell structure—Dual loop split ring resonators are used to obtain wideband and dual‐band responses, respectively. The proposed work discusses the design methodology, and analysis of metacell structure based on a quasistatic model and compares simulation results with experimental results. The proposed dual‐band filter presents an insertion loss (S21) of less than 1 dB and input reflection coefficient (S11) greater than 10 dB in both passbands centered at 3.3 and 5.7 GHz. The designed filter is suitable for wireless communication applications—Wireless Access in the Vehicular Environment. [ABSTRACT FROM AUTHOR]

This letter presents an ×8 frequency multiplier for the W‐band wireless satellite communication in the 65 nm complementary metal‐oxide‐semiconductor process. To reduce the power consumption, the proposed frequency multiplier employs only one driven amplifier and three stages of doublers. All doublers adopt balanced structures to increase their robustness. The output buffer is introduced to ameliorate the impedance matching of output port so that the output power of the proposed ×8 frequency multiplier can achieve 4.63 dBm. Through the special design of the interstage impedance matching circuit, the relative 3‐dB bandwidth of the proposed frequency multiplier is over 25% (from 74.8 to 96.2 GHz). The chip also has a small size and low power consumption, which is 1.37 × 0.51 mm2 and 125 mW, respectively. [ABSTRACT FROM AUTHOR]

Modern wireless communication systems require components that can support microwave and millimeter‐wave bands simultaneously. However, it is difficult for the existing dual‐band crossover configurations to achieve a frequency ratio larger than 5. In this letter, a dual‐band filtering crossover with a frequency ratio larger than 10 is presented for the first time. To implement such a large frequency ratio, a microstrip filtering crossover operating at microwave band and a substrate integrated waveguide filtering crossover operating at millimeter‐wave band are combined through the aperture coupling mechanism. As the two elements almost have no influence on each other, a high degree of design freedom over two bands can be obtained. For demonstration, a dual‐band filtering crossover operating at 2.4 and 28 GHz was designed, fabricated, and measured. Measured results are in good agreement with simulated ones, which validates the proposed structure. [ABSTRACT FROM AUTHOR]

A wide beam miniaturized broadband omnidirectional circularly polarized antenna operating at S‐band is proposed. It is composed of a hub‐shaped circular horizontally polarized radiator, a vertically polarized radiator consisting of a monopole and eight shorting‐circuited pins, and a coupling feed device. The measured results indicate that the impedance matching band of |S11| < −10 dB is from 2.15 to 2.75 GHz (24.4%), and the band of the axial ratio <3 dB is from 2.2 to 2.7 GHz (20.4%). The gain of the antenna is about 1 dB, and the noncircularity in the azimuth plane is <1.2 dB. In addition, the antenna has the characteristics of wide axis ratio beam in the pitch plane with sizes of 0.68 λ0 × 0.68 λ0 × 0.14 λ0. The antenna is very suitable for satellite receiving system and short‐range wireless communication system. [ABSTRACT FROM AUTHOR]

In this letter, a wideband low noise amplifier (LNA) using noise‐canceling topology and gm‐boosting technique is proposed. The noise‐canceling topology is used in the common gate (CG) amplifier to achieved better noise figure (NF) and wideband input matching. Meanwhile, the requirement of the input transconductance can be obviously decreased due to the application of gm‐boosting technique, which effectively alleviate the trade‐off between power consumption and voltage gain. The 3‐dB bandwidth of the LNA is from 2.1 to 4.1 GHz, covering widely used 5 G wireless communication frequency bands (n1, n7, n38, n41, n66, and n78 bands). The proposed LNA shows a flat and low measured NF of 3.3–3.6 dB within the operating bandwidth, while the peak power gain is 18.7 dB. The power consumption of this circuit is 16 mW with 1.2 V supply voltage, and the core area of the circuit is 0.066 mm2 with only one inductor for the whole chip. [ABSTRACT FROM AUTHOR]

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

A broadband high‐efficiency high‐gain empty substrate integrated waveguide cavity‐backed filtenna with dual beams is proposed. The antenna is vertically stacked by three cavities. Two rectangular slots are etched above the uppermost cavity to realize the radiation function. Since the interior of the cavity is covered with metal, the characteristics of the antenna are independent of the used dielectric substrate. The fractional bandwidth of the proposed filtenna is 21.1%, and the efficiency can reach more than 90% in the operational band. The antenna has good frequency selection properties, and the ratio of the −10 dB impedance bandwidth to the −3 dB impedance bandwidth is 0.88. Good gain flatness is obtained, the maximum gain of the filtenna within the operational band is 8 dBi. The proposed dual‐beam filtenna can realize broadband and filtering simultaneously, with low cost and high efficiency. It can be used in wireless communication systems. [ABSTRACT FROM AUTHOR]

The investigation of two half circular patch (HCP) antenna with defected ground structure to operate dual bands is presented in this study for wireless communications. The crescent slots etched on the HCPs are proposed to operate the dual bands of below −10 dB reflection coefficient, with the impedance bandwidth of the first band being 740 MHz (3.01–3.75 GHz) and of the second band being 7120 MHz (6.74–13.86 GHz). The proposed HCP antenna was resonates of 3.36 and 12.17 GHz with −33.9 and −35.47 dB reflection coefficients. This antenna produces a maximum gain of 5.46 and 6.61 dB for these resonating frequencies, respectively. The simulation and measured radiation pattern results are also presented for proposed HCP antenna and it operates for wireless communications and internet of things applications. [ABSTRACT FROM AUTHOR]

A uniquely shaped layout of a wideband circularly polarized (CP) printed monopole antenna is planned in this article. The proposed antenna comprises a 7‐shaped slotted radiating patch, tapered feed line, and modified partial ground plane. Multiple parasitic strips are employed at optimum positions on the ground and radiating planes to improve the axial ratio bandwidth (ARBW). The electrical dimension of the designed antenna is 0.49λ0×0.44λ0×0.03λ0 $0.49{\lambda }_{0}\times 0.44{\lambda }_{0}\times 0.03{\lambda }_{0}$. The confirmed −10 dB impedance bandwidth (IBW) and 3 dB ARBW are 11.86 GHz (3.14–15 GHz), 130% and 6.32 GHz (4.04–10.36 GHz), 87.78% along with 75° $75^\circ $ coverage angle. The proposed antenna is suitable for different applications in communication systems such as WLAN, WiMAX, FM CW altimeter, and satellite for C‐ and X‐ band. [ABSTRACT FROM AUTHOR]

In recent years, there has been a large amount of attention focused on the design of filtering antennas to reduce the front‐end size of modern wireless communication systems. Although numerous design approaches are presented in the literature, they are usually applicable to a certain microwave circuit structure. Additionally, their implementations demand extra matching circuits or a structure which leads to an increase in the filtering antenna size. In this paper, the design of a 3rd‐order filtering antenna operating at the X‐band frequencies is presented utilizing the coupling matrix approach. It is based on 3rd order coupled‐resonators filter without employing any extra structure. For the physical configuration, three inline coupled rectangular waveguide cavity resonators operating at TE101 mode are employed. The output of the last resonator is coupled to free space via a rectangular aperture. The dimensions of the aperture are manipulated to control the radiation quality factor (Qr). To validate the simulated results, the design has been fabricated using the Computer Numerical Control technique. Excellent agreement between the simulation and measurement results has been obtained. The fractional bandwidth (FBW) is more than 10% when the reflection coefficient S11 = −20 dB. The gain response is very flat (7.54 ± $\pm \phantom{\rule{}{0ex}}$0.2 dBi) from 9.5 to 10.5 GHz. The proposed filtering antenna is compact and low profile which may be of interest in radar applications. [ABSTRACT FROM AUTHOR]

Radiofrequency noise is one of the challenging problems in the design of high‐performance wireless communication systems, for which microstrip band‐pass filters are one of the most commonly used design solutions for this challenge. However, for having high‐performance designs. usage of a 3D Electromagnetic simulation tool is a must in which the computation efficiency of the whole design optimization process might not be acceptable or even feasible. An efficient solution is utilization of AI‐based algorithms to create data‐driven surrogate models of the handled problem. In this paper, for achieving design optimization of an edge‐coupled band‐pass filter AI‐based algorithms have been used to create a data‐driven surrogate model. To achieve this, by using a 3D full‐wave simulator a data set for the aimed bandpass filter is generated. Then a series of state‐of‐the‐art regression algorithms, Support Vector Regression Machine, MultiLayer Perceptron, Ensemble Learning, Gaussian Process Regression, and Convolutional Neural Network have been used to create a data‐driven surrogate model for the aimed filter design. In the third step, the obtained data‐driven surrogate model is used to assist an optimization process directed by the Bayesian optimization technique to optimally determine geometrical design parameters of the desired band‐pass filter for sub‐5G applications at frequency of 3.4 GHz. The obtained results of the surrogate model are compared with experimental results and found to be in high agreement level. Furthermore, the performance of the optimally designed filter is compared with the counterpart designs in literature. Thus, based on the obtained results, it can be said that the proposed surrogate‐assisted optimization process is not only an efficient method in terms of computational costs but also is an efficient method to obtain high‐performance microwave filter designs. [ABSTRACT FROM AUTHOR]

In this article, the proposed antenna structure is designed for modern wireless communication systems. The antenna structure is consistent with 11‐unit cells of composite right–left‐hand (CRLH) inclusions mounted on an FR4 substrate. Therefore, the antenna size is miniaturized effectively to 30 × 20 mm2 to cover the frequency bands around 2.45 GHz, for Wi‐Fi, and 4.2–6 GHz, for sub‐6 5G, networks. The design process is conducted on a circuit model and numerical simulations by evaluating the unit cell transmission phase spectra. For this, a comparison between the circuit model and the numerical simulations is invoked for validation. Such an antenna is found to provide a maximum gain of 6.2 dBi at 4.6 GHz. Next, 11 PIN diodes control the current motion between the antenna patch and the CRLH array. Therefore, PIN arrays are connected to the patch and the ground plane to maintain the surface current motion that realizes main lobe beam steering. The proposed antenna performance is simulated numerically using the CSTMWS software package. Then, it is fabricated and tested experimentally for validation. An excellent agreement is achieved between the simulated and measured results. Finally, it is found this antenna provides excellent beam steering −92° to 92° to suit many modern networks. [ABSTRACT FROM AUTHOR]

Multiband bandpass filter is a key component in multistandard wireless communication system. This paper proposes a novel tri‐band bandpass filter (TB‐BPF) which consists of two mesh‐type multimode resonators (MT‐MMR) and two stub‐loaded U‐type feedlines. The MT‐MMR is formed by parallel connecting two open‐end stubs and one mesh‐type structure. Such specific configuration is featured by four inherent transmission zeros. The in‐depth analysis on the generation mechanism of the transmission zeros is made, and then a fast hybrid approach is developed for design procedure. Some explicit design equations are presented for fast determining initial values of some key parameters, and then further optimized by using a constraint condition, which effectively accelerate design process. For verification, an example of the TB‐BPF was designed fabricated and measured. Its center frequencies are at 3.16, 4.27, and 5.70 GHz, respectively. Six transmission zeros are generated for sharp frequency selectivity, and are at 1.46, 3.58, 3.86, 4.73, 5.51, and 7.18 GHz, respectively. Its size is about 0.59 × 0.19 λg2. [ABSTRACT FROM AUTHOR]

A multiband quasi‐Yagi antenna using a stepped driver and slotted ground for the applications of 2.4/3.5/5.2 GHz bands is presented. The ground plane modifications match impedance and help form the resonances, while the stepped driver parameters allow independent control of resonance frequencies. The antenna shows multiband characteristics and has achieved S11<−10 ${S}_{11}\lt -10$ dB in three different frequency bands of 2.15–2.65, 3.4–4, and 5–5.3 GHz. Furthermore, the antenna shows a stable gain of around 3.9–4.9 dBi and retains its general radiation characteristics for all frequency bands. The simulation and measurement results agree well with each other. The proposed antenna is suitable for applications requiring general quasi‐Yagi antenna characteristics for wireless communications applications for WLAN, WiMAX, ISM, and Bluetooth frequency bands. [ABSTRACT FROM AUTHOR]

A monopole rectangular shape patch antenna (RSPA) with trapezoidal shape complementary split ring resonator (CSRR) is designed for wireless communication application is presented in this paper. The trapezoidal shape CSRR is considered to obtain circular polarization and rectangular slit is considered to operate antenna for triple frequencies at 1.88, 4.17, and 6.73 GHz, respectively. The axial ratio of 1.25, 1.05, 1.28 dB is observed and a maximum gain of 6.29 dBi at 1.88 GHz frequency is produced. The RSPA model is designed for mobile and fixed satellite application. [ABSTRACT FROM AUTHOR]

This article proposes a high‐gain quasi‐Yagi antenna using nested metaresonator structures with a systematic design approach. The nested metaresonators are used as a director element instead of conventional strip directors. The gain enhancement of the proposed antenna is based on strong electromagnetic coupling between the driver and metaresonator director elements. The proposed antenna has a gain of 7.6–9 dBi with a bandwidth of 8.6% between 2.43 and 2.65 GHz (S11≤−10 ${S}_{11}\le -10$ dB). It achieves a maximum gain increase of 4 dBi compared to the conventional quasi‐Yagi antenna and 2 dBi compared to the four‐director quasi‐Yagi antenna. The proposed antenna can be used for wireless communication applications that require high gain. [ABSTRACT FROM AUTHOR]

A technique is proposed that improves wireless communication channels in fading environments. The device creates a map of channel measurements. The device then moves its antenna to positions of the previously measured maximum within its reach. Proof‐of‐concept measurements were performed for smartphone‐sized devices in an office environment. A quarter‐wavelength monopole antenna for the 2.4 GHz frequency band successfully kept the channel at local maxima. The results show that small antenna movements over half of a wavelength are sufficient to keep the channel in local maxima, to avoid deep fading notches, and to improve channels over state‐of‐the‐art antennas that move with their devices. A channel model for the wireless communication channel of mobile devices with channel maximum antennas is proposed based on the measurement results. [ABSTRACT FROM AUTHOR]

This paper presents an ultraminiaturized bandstop closed‐loop 2.5D frequency‐selective surface (FSS) for sub‐6 GHz 5G wireless communication. Four metallic vertical vias interconnect metallic elements present on both sides of the substrate to form a modified closed‐loop design. The proposed structure band stops the entire sub‐6 GHz 5G band (C‐band/NR N78 band/LTE 42/43 band) ranging from 3.2 to 3.9 GHz with a resonant notch at 3.62 GHz. This design supports polarization insensitivity and procures maximum relative deviation of 0.5% and 0.2% at 80°incident transverse electric (TE) and transverse magnetic (TM) polarized waves, respectively. The proposed FSS prototype has been fabricated and tested. Experimentally, the resonant notch is obtained at 3.55 and 3.68 GHz under TE and TM normal incident polarized waves, respectively. Moreover, good agreement in the frequency response curves is observed between simulated and measured results. The proposed unit cell is 3.6 × 3.6 mm2 in dimensions, which is 0.04λ × 0.04λ, where λ is the resonant wavelength. [ABSTRACT FROM AUTHOR]

Optical intelligent reflecting surface (IRS) is regarded as a forward‐looking technology to deal with line‐of‐sight limitations in optical wireless communications. This paper proposes an iterative photon counting nonorthogonal multiple access‐multiple‐input–multiple‐output (NOMA‐MIMO) system based on optical IRS. By analyzing the geometric and misalignment losses under turbulence effect in the optical IRS‐based atmospheric channel, we construct the channel fading coefficient matrix of the NOMA‐MIMO system. At the receiver, a novel iterative parallel interference cancellation algorithm based on logarithmic likelihood ratio is developed for signal detection. Through the simulation of bit error rate (BER), the reliability of the proposed system is proved. Quantitatively, the BER performance can achieve 2×10−5 $2\times {10}^{-5}$ at the −165 $-165$ dBJ per bit for the scenario of 3×5 $3\times 5$ MIMO system. Furthermore, the numerical results of the external information transfer process indicated that the proposed system has a rapid convergence performance. [ABSTRACT FROM AUTHOR]

The choice of modulation and waveform is a crucial step for generating a radio signal and designing a wireless communication system. Toward this end, a compromise between low‐complexity and high‐data rate had to be considered when selecting the appropriate transmission technique. Indeed, pulse‐based modulation can be a good candidate for THz system due to its simplicity and it supports very high data over short distance. In this work, we proposed a solution based on multiband on–off keying (MB‐OOK) modulation using a noncoherent receiver. A deferential MB‐OOK transceiver has been evaluated over a THz channel model. A data rate of 54.24 Gbps is achieved with a BER of 10–3 when the distance between transmitter and receiver less than 35 m. Furthermore, the proposed system offers a good compromise between throughput, consumption, and complexity, which allow it to be a good candidate for THz applications. [ABSTRACT FROM AUTHOR]

Recently, the technology buzz on utilization of terahertz (THz) technology in beyond 5G and 6G communication is growing due to the demands for large network capacity, bandwidth, and ultrahigh data rates. The THz frequencies are prudent for short‐range future wireless communication systems as they provide extraordinary channel capacity with data rates from few Gb/s to Tb/s due to its ultra‐wide spectrum bandwidth. However, there exists many challenges in designing devices that operate under THz frequencies. The photo‐conductive antenna (PCA) is one of the crucial components that support realization of ultrafast wireless THz communications. In this paper, investigations on photoconductive antennas with interdigitated electrodes (IDEs) have been presented for THz communications with an equivalent circuit model for IPCA with corresponding solved expressions. The results show that the maximum THz field strength of 4.41 × 105 V/m is achievable by a 10 μm interdigitated teeth length IPCA with larger spectrum bandwidth of about ~8 THz. The antenna module makes the possibility of miniaturization of the THz sources and detectors for the emerging variety of wireless THz applications. [ABSTRACT FROM AUTHOR]

A wideband and wide beam‐width dual‐polarization with a low‐profile and simple structure is presented in this letter. The proposed antenna comprises two pairs of bending plates, the feed part that includes the probe and the copper disk, and two series of feeding networks. A couple of the bending plates can be used to form the horizontal and vertical currents to broaden the antenna's beam width. To radiate a symmetrical wide beam pattern, a series feeding network is applied to guarantee a symmetrical current distribution on the bending plates. Therefore, the proposed wide beam capability has been analyzed and verified with a dual‐polarization antenna. A low‐profile dual‐polarization antenna is demonstrated, which can realize the half‐power beam‐width more than 180° and 100° in the E‐ and H‐plane in the whole operating frequency band (22.3%), respectively. Furthermore, the port isolation is lower than −35 dB in the most frequency band. The prototype is fabricated and characterized, yielding good performance within the overall operational bandwidth. The measured results align very well with the simulated results. The proposed wideband antenna is a promising candidate for wireless communication systems because of the dual‐polarization and wide beam‐width. [ABSTRACT FROM AUTHOR]

In this paper, a novel compact patch antenna is presented for wireless communication applications. The proposed antenna has three T‐shaped patches (TSP) connected to the feed line and crossed I‐slots are etched on the ground plane to operate a single resonating band with low interference. The TSP antenna operating frequency is 10.98 GHz with an impedance bandwidth of 850 MHz, a reflection coefficient of −38.11 dB, and a gain of 6.44 dBi. The radiation patterns are also presented for E‐plane and H‐plane. The proposed TSP antenna model is fabricated and tested. Good agreement is achieved with simulated and measured results. [ABSTRACT FROM AUTHOR]

A wideband dual‐polarized antenna with high isolation is proposed for full‐duplex applications. It consists of a radiating patch, two E‐shaped strips, a parasitic patch, a metal reflector, and a 180° power divider. Two hook‐shaped strips and a pair of E‐shaped strips are used to excite the radiating patch realize ±45° polarization. The impedance matching is significantly enhanced by the attendance of the parasitic patch and 180° power divider. Multiple decoupling techniques, including polarization diversity, radiation mechanism diversity, shunt effect of a shorting pin, and differential feeding, are simultaneously used to achieve high isolation. An antenna prototype is measured with an impedance bandwidth of 52.2% (1.7–2.9 GHz) for |S11|, |S22| < −10 dB, and high isolation of better than 55 dB. These characteristics make it a promising candidate for in‐band full‐duplex wireless communication systems. [ABSTRACT FROM AUTHOR]

Reconfigurable dielectric liquid‐assisted antennas provide a solution to the need for multifunctional antennas that can service the multiple frequency bands required for modern wireless communications. However, fabricating these reconfigurable antennas requires complex processes that lack the potential for more compact designs. In this study, a novel continuously reconfigurable dielectric liquid‐assisted microstrip patch antenna fabricated with a Shrinky‐Dink millifluidics‐based substrate is designed, fabricated, and characterized. Shrinky‐Dinks are prestretched polystyrene sheets that can have patterns cut into them before shrinking under heat to form a millifluidic channel. By filling the millifluidic channel with differing amounts of water, a microstrip patch antenna fabricated on top of the rigid polystyrene substrate can be continuously reconfigured from 4.70 to 5.16 GHz with a bandwidth of 660 MHz. The fabrication process demonstrated in this study provides a path forward to produce reconfigurable dielectric liquid‐assisted antennas with smaller footprints, as well as other reconfigurable radiofrequency and electronic devices and components. [ABSTRACT FROM AUTHOR]

This paper proposes a novel decoupling and matching technique to enhance port isolation and broaden their common operating bandwidth for asymmetric antenna arrays. The original antennas have strong mutual coupling and a large inconsistency of bandwidths. After adding the proposed network, the coupling has been suppressed and their operating bandwidths have been equalized. To verify this technique, a reference and proposed antenna arrays with element spacing of 0.1506 λ0 ${\lambda }_{0}$ (λ0 ${\lambda }_{0}$ is the wavelength in free space at the center frequency point) are simulated and fabricated. In the experiment, the port isolation is improved by about 23.7 dB at the center frequency. Their bandwidths with a reflection coefficient of −15 dB are also equalized. The common bandwidth is enhanced by about 110.63%. The proposed antenna array has potential application value in modern wireless communication. [ABSTRACT FROM AUTHOR]

Antennas applied in wireless communications are required to have omnidirectional radiation in horizontal plane and low profile. But, the low profile make the antenna challenging to obtain high horizontal gain. In this paper, we proposed a novel high gain antenna with near‐zero‐index metamaterial (NZIM). The horizontal gain of antenna with omnidirectional radiation is improved by 1.30 dBi. In addition, the increment of horizontal gain increases as the refractive index of NZIM unit approaches zero. It can be applied to further optimize the horizontal gain. This novel antenna has low profile (about 0.034λ) with high horizontal gain and omnidirectional radiation, which is suitable for wireless communications. [ABSTRACT FROM AUTHOR]

After the deployment of 5th generation (5G), the beyond 5G (B5G) and 6th generation (6G) communication grabs the critical attention of academia and researchers. In ongoing cellular generation, the selected radio spectrum (i.e., millimeter waves [mm‐Wave]) is unable to achieve the required data rates. Future cellular generations need more data rate and link reliability to serve emerging intelligent applications of B5G and 6G (e.g., autonomous driving, virtual reality, etc.). To handle these limitations of ongoing cellular generation, the researchers are working on key factors to have a smart, high capacity and ultra‐reliable propagation environment. To increase the data rate of the B5G and 6G network systems, the terahertz (THz) band is selected. However, to increase link reliability, the intelligent reflecting surfaces (IRSs) have a crucial impact on wireless network environments. Immense work has been done on the performance analysis of IRS‐assisted wireless communication networks. This treatise imposes a comparison of such IRS‐assisted THz communication systems, and future promising applications. [ABSTRACT FROM AUTHOR]

A novel wideband Doherty power amplifier with high‐drain efficiency is proposed in this paper. The triode CGH40010F is adopted in carrier amplifier and peak amplifier to realize the power amplification, respectively. The wide bandwidth is achieved by using the two‐point impedance matching circuit, which can be applied to achieve good matching of peak output power point and power back‐off point at the same time. The drain efficiency at peak output power point is greater than 55.8% and the maximum drain efficiency is 71.3%, while the peak output power is greater than 43.2 dBm (with an error of ±0.7 dBm) from 1.8 to 2.8 GHz. The drain efficiency at 6 dB power back‐off point is greater than 45.1% and the maximum drain efficiency is 63.2%. [ABSTRACT FROM AUTHOR]

In today's pandemic environment where most of the work is managed from the premises of home, high bandwidth internet connectivity with superior signal quality is essential. Hybrid technologies based on optical wireless communication (OWC) are a better candidate for such requirements of next‐generation communication networks. Such systems, also suffer from transmission impairments like crosstalk and dispersion affect the quality of the transmitted signals. In this article, the impact of crosstalk in the presence of higher‐order dispersion (HOD) on a hybrid OWC access network is assessed. Coupled expressions have been employed for estimating crosstalk due to HOD in hybrid access systems. The mathematical model for XPM induced crosstalk has been introduced. Further, the impact of different system parameters on SRS and XPM induced crosstalk has been observed, so that the quality of communicated signals may be improved. [ABSTRACT FROM AUTHOR]

A rapid growth in 4G and 5G in wireless communication applications demand compact and reconfigurable microstrip filters structures. However, meeting these requirements comes with many challenges, namely the increased design complexity, system size, fabrication process, and cost‐effectiveness. Accordingly, the paper aims to design a reconfigurable microstrip filter in terms of its geometrical structures of compactness and its operational performances. A reconfigured compact parallel‐coupled microstrip bandpass filter is a modified Minkowski fractal geometrical shape of inverted alphabet C structure and the first iteration of Minkowski is proposed. The proposed work shows the design technique, parametric analysis, and simulated results of a compact parallel‐coupled microstrip Minkowski fractal bandpass filter for dielectric constant 4.4 and thickness 0.8 mm, operating at 5.1 GHz and bandwidth of 1.5 GHz. A good agreement between simulated results and designed values is achieved, the filter is compact with good bandwidth, less loss, and is dedicated to wireless communication applications. [ABSTRACT FROM AUTHOR]

An n‐shaped antenna with multimode for wideband application based on substrate integrated suspended line (SISL) platform is presented using characteristic mode analysis (CMA). By exciting three modes simultaneously, a wideband characteristic is achieved. The size of the proposed antenna is 0.74 λ0 × 1.47 λ0 × 0.11 λ0 (where λ0 is the free‐space operating wavelength at the center frequency of 6.205 GHz). The antenna prototype is fabricated and measured. Experimental results show that in the band of 5.1–7.31 GHz, |S11| <−10 dB, and the realized gain is from 5.2 to 9.8 dBi which can be used for WLAN and 5G wireless communication system. [ABSTRACT FROM AUTHOR]

A miniaturized quasi‐Yagi antenna is presented using a defected ground structure and double dog‐bone driver. The antenna has a simplified feeding structure. With the help of the dog‐bone driver and slotted ground structure antenna's resonance frequency is lowered. Thus, the miniaturization is achieved. Additional angled dog‐bone driver and circular patches in the ground improve impedance matching and bandwidth characteristics. The overall size of the proposed miniaturized quasi‐Yagi antenna is 0.29λL×0.3λL, where λL is the wavelength at the lowest operating frequency(∣S11∣≤−10 dB). The antenna achieves ∣S11∣≤−10 dB between 2.35 and 2.65 GHz in the simulation, 2.36 and 2.63 GHz in the measurement. The antenna has a gain of 3.8–5.4 dBi, over 81% total efficiency, and stable end‐fire radiation characteristics in the frequency range of operation. The proposed antenna is a good candidate for compact portable wireless communication systems. [ABSTRACT FROM AUTHOR]

This letter introduces a wideband circularly polarized (CP) array antenna for wireless communication application. The array consists of 2 × 2 sequentially rotated symmetric antenna elements and a wideband weakly coupled feed network providing stable 90° phase difference. By using the proposed feed network and introducing the slot coupling feed, the CP array antenna can achieve a wideband CP performance with a low profile of 0.03 λ0 (at 5.0 GHz). The proposed antenna exhibits the impedance bandwidth (IMBW) of 73.9%, axial ratio bandwidth (ARBW) of 53.6%, and 3‐dB gain bandwidth (GBW) of 60% with the peak gain of 10.4 dBi and the maximum efficiency of 82%. The measured results are in good agreement with the simulated results, indicating that a promising application in compact wideband C‐band wireless systems. [ABSTRACT FROM AUTHOR]

Design of ultra‐wideband (UWB) dual‐polarized magnetoelectric (ME) dipole antenna with compact size is presented. The proposed antenna consists of a double‐layer ME dipole, a pair of cross‐placed Γ‐shaped probes, and a box‐shaped reflector. Total size of the final design is 95 mm (0.87λ0) × 95 mm (0.87λ0) × 65 mm (0.6λ0). Both simulated and measured results show that the proposed antenna has an operating bandwidth of 127.3% (1–4.5 GHz) with voltage standing‐wave ratio (VSWR) ≤ 2.2 and 5.1 dBic ≤ gain ≤ 9.6 dBic. A stable unidirectional radiation pattern is achieved over the whole band. The cross‐polarization level is less than −15 dB and isolation between two ports exceeds 15 dB. Due to its compact size and good performance, the proposed antenna can be a competitive candidate in most wireless communication application scenarios. [ABSTRACT FROM AUTHOR]

A compact pattern diversity patch antenna working at 5.8 GHz is proposed. The patch antenna has two ports, which are responsible for the broadside radiation and omni‐directional radiation, respectively. The broadside radiation is achieved by inserting a substrate slot‐loaded integrated waveguide (SIW) cavity at the center of the patch antenna, and the omni‐directional pattern is realized by exciting the shorted patch in‐phase from both sides of the SIW cavity. Although the two operating modes share the same radiator, but a high isolation of over 30 dB is achieved, due to the cancellation of current at the inputs. In addition, two approaches are investigated to enhance the operation bandwidths. The pattern diversity antenna is prototyped and measured, showing an impedance bandwidth of 5.69–5.92 GHz for both modes/channels, and a high inter‐channel isolation over 30 dB, making it suitable for indoor wireless communication systems. [ABSTRACT FROM AUTHOR]

In this work, design of a pattern reconfigurable antenna is presented for X‐band applications as a leaky wave antenna (LWA) realization. Due to the advantages of simple design schematic, low profile, and easy impedance matching, LWA designs have been using as an efficient solution for reconfigurable antenna in many wireless communication applications. Optimization and simulation of the proposed LWA is carried out in 3‐D Microwave simulation CST environment and Honey Bee Mating is used as the optimization algorithm. Dimensions of the proposed LWA is 130 × 30 mm, which is fabricated on Rogers 5880 as capacitive loaded eight identical rectangular microstrip patches operating over 9.5‐12 GHz with a fractional bandwidth. The proposed LWA exhibits a measured peak gain of 11.8 dBi at 10 GHz with an overall gain characteristic of between 9.5 and 11.8 dBi over the range of 9.5 to 12 GHz with a steerable pattern characteristics between −45 and 50° as agreed with the theory. Furthermore, the fabricated LWA has been found to have the superior performance as compared with its counterparts. [ABSTRACT FROM AUTHOR]