An elliptical shape patch (ESP) antenna with inverted U-shaped slots is proposed and presented in this paper for on-body communication. A coplanar waveguide (CPW) feed is used as ground to produce impedance matching, and inverted U-shaped slots are used to produce the ultra-wideband (UWB). The proposed ESP antenna model covers UWB characteristics in free space, and it is observed at 3 to 10.7 GHz. When it is implanted on flat tissue model of human body, the bandwidth is 2.2 to 10.8 GHz. The SAR values of 1.26 W/kg and 1.58 W/kg are observed on-body at 4.9 GHz and 7.3 GHz operating frequencies, respectively. The results with respect to radiation pattern, gain, reflection coefficient, surface current distribution are also presented.

Various resonance modes, high transmission, and quality factor with simple design are highly desirable parameters for realizing nano-integrated plasmonic devices. In the context, a plasmonic structure consisting of two straight waveguides MIM coupled one central defective circular nano-disk resonator (CNDR) is proposed in this work. The insulator and metal of the proposed plasmonic filter are air and silver, respectively. The plasmonic filter is designed and investigated numerically by using the finite difference time domain method (FDTD). Our simulation results indicate that the proposed plasmonic filter has two transmission peaks with a maximum transmission equal to 80 and 70 percent. The advantages of the proposed filter are the various resonance modes with high transmission peaks and high quality factor which reaches 35.27. In view of these features, our proposed structure of plasmonic filter has the potential to be employed in various devices such as plasmonic demultiplexers and sensors for optical communication purposes.

Reconfigurable intelligent surface (RIS) has been suggested as a promising solution to prevent wireless communication systems from transmission blockage. In this paper, the performance of reconfigurable intelligent surface in cooperative decode-and-forward relaying for hybrid radio frequency (RF)/free space optical (FSO) system is evaluated where parallel transmission of information occurs on the system downlink. In this network, the RF links in the system are assumed to follow Nakagami-m distributions while the FSO link is subjected to Gamma-Gamma distribution. Thus, the exact closed-form expressions of the system outage probability and average bit error rate are obtained to quantify the system performance. The accuracy of these expressions is justified by the Monte-Carlo simulations. Also, to get more physical insight from the derived outage probability expression, the asymptotic outage probability under the condition of higher signal-to-noise ratio (SNR) is provided. In addition, the results illustrate that the system and channel parameters significantly affect the performance of the concerned system. Furthermore, the results show that RIS-hybrid downlink system offers better performance than hybrid downlink system without RIS. Under the RIS system, the results demonstrate that RIS-hybrid downlink system outperforms RIS-FSO downlink system.

The design of an innovative breast model system that focuses on a wideband for the detection of malignant tumours is described. The planned antenna has an overall area of 18×28 mm² and a fractional bandwidth (FBW) of 99% across a frequency spectrum of 3.4-10 GHz. The suggested antenna has excellent impedance matching, a considerable gain of 3.95 dBi, maximum efficiency of 96.98%. Omnidirectional radiated patterns are verified in the frequency, and time-domain analysis is also investigated for breast tumor diagnosis. For detecting a breast tumor with accuracy, the suggested antenna S₂₁ parameters are evaluated together, including imaging outcomes of current densities and specific absorption rate (SAR). These findings show that the radiator and the whole system work well at finding the tumor.

Bipartite systems have become popular in emerging quantum radar and quantum communication systems. This paper analyzes the various correlation coefficients for different types of quantum radar measurement schemes, such as: (i) immediate detection of the idler photon events to be used in post-processing correlation with the signal photon events, (ii) immediate detection of the idler electric field to be used in post-processing correlation with the signal electric field, (iii) immediate detection of the idler quadratures to be used in post-processing correlation with the signal quadratures, and (iv) conventional analog correlation method of the optical parametric amplifier. The showcased results compare the performance of these different methodologies for various environmental scenarios. This work is important at developing the fundamentals behind quantum technologies that require covariance measurements and will permit more accurate selection of the appropriate measurement styles for individual systems.

For the last 20 years, the time-reversal (TR) process has been successfully applied to focus pulses in the microwave frequency range and in complex media. Here we examine the specific conditions to obtain the same results but in the sub-THz frequency range. Because of the stronger attenuation at this much higher frequency, it is more challenging to exploit the TR self-focusing property. The TR of pulses is studied in two kinds of complex media: metallic waveguide and leaky reverberating cavity. For each medium, we propose one or two models to assess the quality of the focusing. For the waveguide, we show that the angle of incidence is an important parameter. Based on these results, we perform TR experiments at 273 GHz with a bandwidth that can be as large as 2 GHz. TR experiments are successfully first conducted in a 1 m long and 10 mm diameter straight hollow cylinder and then in a 5 m long and 12 mm diameter curved waveguide. Finally, we present results obtained in a cavity of 72 cm³ that leaks through a copper grid. The best focusing is observed with the longer waveguide.

In this work, we present numerical results regarding the effects of temperature on the omnidirectional photonic band gap (OPBG) of ternary 1DPC containing metal (Ag) layer or graphene layer. By periodically introducing layer metal (Ag) or graphene into 1DPC, the width of OPBG has been increased. As the temperature increases, the photonic band gap of the OPBG becomes wider. Compared to the conventional OPBG in ternary 1DPC containing Ag, the OPBG in 1DPC containing graphene with temperature T = 1000˚K is greatly broadened by 2.04 times. The theoretical basis of our study adopts the transfer matrix method TMM. In fact, these broad omnidirectional and thermally tunable OPBGs will offer many prospects for omnidirectional mirrors, temperature sensing device, optical filters, polarizer, and other optical devices.

The integration of radar and communication has always been one of the cross-research hotspots in the field of radar and communication. In order to solve the problems of integration signal separation and the angle-distance coupling, this paper proposes a radar and communication integrated waveform based on random Orthogonal Frequency Division Multiplexing (OFDM) frequency offset modulation for Frequency Diversity Array (FDA). This waveform directly loads OFDM symbols to the elements of FDA, and each element carries a complete OFDM symbol with different information. Random frequency offsets are added between the elements to separate different signal of different elements, which can solve the problem of signal separation and form decoupled radar beam. After transmitting and receiving a series of the waveform, the transmission of communication data and the positioning of radar targets can be completed at the same time. The simulation results show that the waveform not only solves the problem of separating and uncoupling the integrated signal, but also improves the frequency band utilization rate and information transmission rate of the radar communication integrated system.

The marching-on-in-time electric field integral equation (MOT-EFIE) and the marching-on-in-time time differentiated electric field integral equation (MOT-TDEFIE) based on a Rao-Wilton-Glisson (RWG) spatial discretization. In both formulations we employ the Dirac-delta temporal testing functions, however they differ in temporal basis functions, i.e. hat and quadratic spline basis functions. These schemes suffer from the linear-in-time solution instability. We analyze the corresponding companion matrices using projection matrices and prove mathematically that each independent solenoidal current density corresponds to a Jordan block of size two. In combination with Lidskii-Vishik-Lyusternik perturbation theory we find that finite precision causes these Jordan block eigenvalues to split and this is the root cause of the instability of both schemes. The splitted eigenvalues cause solutions with exponentially increasing magnitudes that are initially observed as constant and/or linear-in-time, yet these become exponentially increasing at discrete time steps beyond the inverse square root of the error due to finite precision, i.e. approximately after one hundred million discrete time steps in double precision arithmetic. We provide numerical evidence to further illustrate these findings.

A new design of a 2×2-element subarray antenna based on an all-cavity resonator structure is presented in this article. A novel topology which employs only two resonators to lay out the subarray is proposed, and two X-band rectangular waveguide cavity resonators are utilized for the subarray physical implementation. The first resonator is a conventional half-guided resonator operating at the TE₁₀₁ mode. The second resonator, which is an oversized TE₁₀₂ resonator based, is modified in order to keep the TE₁₀₁ mode to propagate within the bandwidth of interest and facilitate the connection with four radiating apertures. The developed coupling matrix approach is utilized to calculate the desirable frequency response, which is a standard 2nd order Chebyshev response with introducing filtering functionality to the realised gain response of the subarray. The simulation results obtained by two simulation softwares (CST and Ansoft HFSS) validate the calculation results. An extremely wide impedance bandwidth of 23% at center frequency 10 GHz when the reflection coefficient S₁₁ = -10 dB is obtained. A very stable realised gain with less than 0.5 dBi variations over the bandwidth of interest (8.8-11.1 GHz) is obtained with a peak gain value of 13.1 dBi at 11 GHz. The radiation patterns have very low side lobe levels, particularly in the E-plane, due to the existence of small non-radiating area and maintaining small spacing between the radiating apertures. The proposed 2×2-element subarray has the advantages of wider bandwidth and low profile compared with our and other previous 2×2-element subarrays.

A dual-band hexagon shape substrate integrated waveguide (SIW) based band pass filter with single loop complementary spilt ring resonators (CSRRs) is introduced in this paper. The design parameters of this filter are optimized by using artificial neural networks (ANNs). Especially error back propagation multilayer perceptron (EBP-MLP) neural network with Levenberg-Marquart (LM) algorithm is used. A physical prototype of the proposed model is fabricated and tested. In the lower passband from 10.2 to 10.6 GHz, the insertion loss is about -0.8 dB with a fractional bandwidth of 3.85%, and in the upper passband from 12.11 to 13.31 GHz, the insertion loss is about -0.8 dB with a fractional bandwidth of 9.56%. It is observed that the insertion loss is same in both the passbands. The obtained experimental results are in good agreement with the estimated results using full-wave analysis and ANN optimization.

This paper presents a dual-band dual-polarized antenna including one L-band vertically polarized antenna, four C-band horizontally polarized subarrays and four C-band vertically polarized subarrays. Both the L- and C-band radiation elements are designed based on the concept of slotted coaxial waveguide antenna. The coaxial waveguide structure is in rectangular shape which is suitable for multi-element integration. And bending stripline inside the waveguide cavity plays the role of inner connector for the coaxial waveguide and exciter for radiating slots on the waveguide. Results show that impedance bandwidths of 14.9% for L-band and 5.9% for C-band are obtained with good port isolation. The antenna also exhibits good radiation performance with the low cross-polarization. The results indicate that the proposed antenna is suitable for synthetic aperture radar applications.

A high frequency device design and simulation results are reported for an 8 x 8 phased array of unit cells. Each unit cell comprises a (3 x 3) sub-array of 1/4 wave rod monopole radiators. Each unit cell is the basic building block that can be arranged to form 9 interpenetrating arrays. Each interpenetrating array comprises an independently addressable 8 x 8 array of 1/4 wave rod monopole radiators that fits into the lateral space of a single 8 x 8 array of patch radiators but can operate on 9 independent radio frequency channels within the same contiguous communication band without interference and can direct each radio frequency channel into independent directions simultaneously. The beamformer architecture, operation principle, and simulation results are presented and discussed, and an outline of its construction based on 2.5D integration is presented.

In this article, two compact Substrate Integrated Waveguide (SIW) bandpass filters based on Defected Ground Structure (DGS) technology are proposed. Hilbert Cell of second orderis the resonator shape proposed for the DGS of both filters, where the first filter DGS consists of five pairs, and the second one uses only three pairs. The pair used in the first filter consists of two cells located side to side whereas they are placed face to face in the second filter. In order to enhance the performance of the second filter and based on the evanescent-mode technique, three other pairs of first order Hilbert cells are engraved on the top layer. Both band-pass filters are designed to operate in C band with a measured bandwidth of 1.8 GHz for the first filter and 0.86 GHz for the second one. The proposed structures have the same physical dimensions, which is 38.1 mm×16 mm with different measured insertion losses of -2.5 dB and -2.7 dB. Both structures exhibit an upper stopband rejection with attenuation around -20 dB and -29 dB, respectively. The filters operate in a transmission bandwidth of [5.5 GHz-7.3 GHz] and [5.27 GHz-6.13 GHz] with a fractional bandwidth (FBW) of 28.1% and 15.09% for the first filter and the second filter respectively. A good agreement is reported between the measured and simulated results.

This work presents a design and analysis of a high gain Antipodal Vivaldi Antenna (AVA) with quad band notch characteristics for Ultra-Wideband (UWB) applications. The proposed AVA is designed on a 1.2 mm FR4 substrate with dielectric constant 4.3 and loss tangent 0.025. Initially, the AVA parameters are optimized in a full wave simulator to get the required UWB performance. The UWB performance is further improved significantly by cutting a C shaped slot from the AVA flares. The C shaped slot introduces an extra resonance that widens the initial bandwidth. The band-notched filtering characteristics are achieved by - adding a Sun Shaped Slot (SSS) on the top and bottom flares of the AVA, inserting a hexagonal shaped Complimentary Split Ring Resonator (CSRR) on the ground plane of the AVA and finally by inserting vias on either side of the feed line. The first designed notch band is from 2.2-2.7 GHz, covering the Bluetooth region. The second notch band is designed from 3.3-3.6 GHz, corresponding to WiMAX applications, and the third notch band is from 4.6-5.7 GHz corresponding to the WLAN band. Finally, a notch is fashioned from 8.8-9.5 GHz, corresponding to ITU applications. The simulated and measured return loss plots show that the antenna achieves an impedance bandwidth of 1.15-14 GHz with a reflection coefficient less than -10 dB, except at the four eliminating bands. To the best of the authors knowledge, the proposed technique is novel, and it allows good narrowband rejection over the UWB regime.

As unmanned aerial vehicle (UAV) is widely used in many civilian fields the wideband (WB) high power electromagnetic radiation devices development, whether the WB radiation would influence the civilian UAV to fulfil its tasks needs to be analyzed. Therefore, the radiated susceptibility of three models of DJI UAVs is studied in the paper. A decimetric wave oscillator with the power of over 500 MW was introduced as the radiation source. In experiment, adjusting the distance between radiation antenna and UAVs to change the electric field and the testing antenna was employed to measure the electric field on line. The three models of UAVs can be shot down by the electric field of 10 kV/m, 20 kV/m and 30 kV/m, respectively. Besides, as electric field reached up to over 35 kV/m, the rotor motor, electric control system and inertial measurement unit (IMU) in Mavic Air and Mavic Air 2 were easier to burn down. Except that, the energy accumulation effect has been proved in the experiment. In conclusion, the UAVs should fulfill tasks in the WB electromagnetic environment whose electric field is much less than 10 kV/m, and some shielding methods are needed to make UAV survive.

In this paper, we propose a wideband polarization diversity multiple-input multiple-output (MIMO) antenna array for 5G smart mobile devices. The proposed MIMO antenna array consists of 8-ports dual-polarized L-shaped lines that highly excite radiating slots, where the elements are placed at four-corners of a compact mobile unit of size 75×150 mm². The uniqueness of the proposed MIMO antenna structure comes from the deployment of octagon-shaped resonant slots within the metallic ground plane, i.e. the octagonal-slots are etched from the bottom (ground) layer of the main mobile board. Due to the unique slots in the ground plane, wideband impedance has been achieved (3.38-3.8 GHz at -6-dB threshold). The proposed smart phone 8×8 diversity MIMO antenna is designed to support the spectrum of commercial sub-6 GHz 5G communications and cover the frequency range of around 3.5 GHz band with high decoupling between antenna ports. The proposed array is designed, numerically simulated, fabricated and tested. Good agreement between simulated and measured results was achieved. The MIMO antenna has a satisfactory far-field performance along with very low envelope correlation coefficient (ECC) < 0.055, high diversity of more than 9.95, and very low specific absorption rate (< 1 W/Kg for a 10-g human tissue).

In this work, a novel all-textile washable metasurface antenna is designed for WBAN/WLAN and mid-band 5G applications. Metasurface antenna is obtained by implanting SRR (Split Ring Resonator) metamaterials that show left-hand characteristics to the patch plane. The metasurface arrays consisting of 4×1 and 4×2 SRRs are placed to both sides of a circular patch. The performance of the antenna is verified by a full-wave electromagnetic analysis tool. The results show that metamaterial arrays significantly increase gain and efficiency values of the circular patch antenna. Metasurface antenna consisting of 4×2 array of metamaterials increases the efficiency from 74% to 94.5% and the antenna gain from 6.81 dBi to 9.43 dBi. Performance of the antenna is observed on conformal surfaces, as well. An analysis is carried out to calculate the peak specific absorption rate on an arm phantom. Patterns of vertically bended antenna in ø=0° and 90° planes and low SAR values up to 30 dBm input power proved suitability of the metasurface antennas for on-body applications. The antennas are fabricated by using standard textile manufacturing techniques. It was confirmed by the measurement results that the metasurface formed by the linear SRR arrays increases the antenna gain. With its low cost, fabrication with standard off-the-shelf parts, high gain, and efficiency features, the proposed antenna can be used in wireless body area networks and 5G applications.

One of the common ways to design large arrays is by designing a small subarray known as cluster and using it as a repeating element throughout a large array. In this paper, the genetic algorithm is used to optimize the clustered amplitude tapers such that the final array pattern has minimum grating lobes and controlled sidelobe level. The formulation of the synthesis problem includes the minimization of the excess magnitude of the grating lobes or peak sidelobes which are usually higher than a given allowable limit. Moreover, two clustered configurations based on increased/decreased number of elements per cluster around the array center are introduced. Correspondingly, their clustered sizes increase/decrease as they approach the center of the array. Simulation results show that the proposed method has capability to optimize clustered linear and planar arrays without noticeable appearance of undesirable grating lobes. The analysis for an array composed of 20 elements with clusters of different cluster sizes M = 10, 8, 5, 4 and different numbers of elements per cluster N_s = 2, 3, 4, 5 elements found that the complexity reductions were 50%, 60%, 75%, 80%; peak sidelobe levels were -29 dB, -23.6 dB, -21.3 dB, -19.15 dB; and the directivities were 25.53 dB, 25.64 dB, 26.33 dB, 26.32 dB, respectively.

It is of great practical value to study the blended rolled edge of reflector used in Compact Antenna Test Range (CATR). Taking a rectangular aperture reflector as the benchmark, a reflector with ideal blended rolled edge is obtained by means of parameter iterative optimization after accurately establishing the position relationship between the local and global coordinates where the blended rolled edge is located, precisely deriving the geometric equation of the main reflector zone and blended rolled edge zone in the local coordinate, and optimizing continuity condition of curvature radius. On the basis, a blended rolled edge reflector with minimum operating frequency of 0.8 GHz and quiet zone size of 2 m is designed. The simulation results show that the performance of the reflector with blended rolled edge obtained by the proposed method is better than that obtained by the traditional construction method, and the designed reflector has excellent performance. The work in this paper provides a theoretical support for the optimal design and engineering application of the blended rolled edge reflector.