In this work we demonstrate the extended and generalized methodology for the design of Quad-Furcated Profiled Horns (Q-FPHs). Based on a design case of a 4λ₀×4λ₀ Q-FPH, we extract the Generalized Scattering Matrix (GSM) of the enlarged quad-furcated discontinuity and provide analytical expressions for its multimode feeding. Next, the four feeding and the upper common waveguide sections are optimized accordingly through Mode-Matching (MM). The high aperture efficiency levels delivered by the methodology are verified by full-wave simulations of the optimized design case and compared to the state-of-the-art which is thereby redefined.

The evolution of computing and network technologies which involve thousands of devices that are connected wirelessly to serve variety of applications in Internet-of-Things (IoT) draws significant interest in locating the indoor objects. In our paper, we focus on developing a hybrid source positioning technique with off-the-shelf hardware modules. A rectangular corridor with a multipath environment is considered in our work. For better localization accuracy, the corridor is classified into segments with threshold RSS values. Based on the measurement data segment-wise logarithmic regression models are developed, and the performance in terms of Correlation Coefficient (R2) and Root Mean Square Error (RMSE) is evaluated. For localization, basically trilateration is used. However, to overcome the adverse issues due to the indoor environment such as flip ambiguity, uncertainty in range measurements, circumscribing the circle's scenarios, two circle intersection, dynamic circle contraction, and expansion methods are used. Relevant Pseudocode algorithms are presented. The proposed hybrid method significantly improves the localization accuracy. The standard deviation of errors in x and y directions are about 16.75 cm, 66.24 cm in the first segment and 19.75 cm, 60.16 cm in the second segment. The analysis and results are useful in establishing state of the art IoT and future generation 5G networks.

A target detection method based on polarimetric multi-domain feature fusion is proposed in this paper to improve the detection performance of slow small targets on the sea. Firstly, a complex symmetric matrix was established based on the Pauli scattering vector. On the basis of an analysis on the matrix, the Takagi decomposition method was adopted to extract the normalized polarimetric maximum eigenvalue to characterize the echo signal. Secondly, a real symmetric Hurst exponent matrix was constructed by processing the echo signal of the polarimetric radar, and the normalized polarimetric Hurst exponent was extracted by the eigenvalue decomposition method. Thirdly, the normalized polarimetric Doppler peak height was extracted through the Doppler peak height algorithm. Finally, by fusing multi-domain features, a false alarm controllable detector was constructed through the convex hull algorithm. The results of experimental analysis on the measured datasets indicate that when the parameters are the same, compared with the traditional detection methods based on polarimetric features, the proposed method presents better robustness in the case of short observation time and low signal to clutter rate.

RF and mm wave filterssuffers from a common problem of asymmetries in filters transmission response caused by unwanted field couplings between individual resonators. In this paper, unwanted or spurious couplings between non-adjacent resonators are identified in the filter network from the simulation stage and mitigated to the extent possible. A 4-pole Quasi Elliptic Planar Band Pass Filter is fabricated at 48.5 GHz on a Liquid Crystal Polymer (LCP) substrate. An improvement of 6 dB in side lobe imbalance in filter transmission response is obtained. Effect of spurious coupling on band pass filters transmission response is demonstrated through EM simulation. Commensurate measurement results are presented.

This work is purposed to provide microstrip antennas for a CP-SAR system with low sidelobe, tilted beam, and circular polarization. This antenna is configured for the L-band (1.27 GHz) mounting on an Unmanned Aerial Vehicle (UAV). The proposed microstrip antenna consists of three-square radiating elements, due to the ease in fabrication. Meanwhile, the proximity structure has been adopted in the feeding network. The tilted beam was obtained by arranging the different phases for each element. On the other hand, a low sidelobe was achieved by managing the power distribution of each patch using the Chebyshev polynomial. The proposed antenna was precisely printed and examined in an anechoic chamber to verify the characteristics of the antenna such as polarization, sidelobe level, and beam direction. Based on the measurement results, the proposed antenna has a tilted beam and a low side lobe that meets the specifications of the CP-SAR system.

In this paper, best arrangement of overhead transmission line conductors is determined via the ant lion optimization (ALO), to minimize the emitted electric and magnetic fields. Compute delectric and magnetic fields are compared with measured datain order to confirm the validity and usefulness of the formulation. ALO algorithm is applied to optimize both single and double circuit transmission lines. The two cases of spacing between line conductors are considered, namely, taking into account the effects of ice and wind, and neglecting the effects of ice and wind. IEC-71 standards are followed for the spacings in both cases. A MATLAB computer code based on ALO algorithm is written for finding the positions of line conductors that will minimize field emissions. Significant reduction of the fields is observed owing to the new optimized positions of conductors. The optimized results of ALO are compared with previous results obtained by genetic algorithm and particle swarm optimization. To the authors' knowledge, this is the first paper that applies ALO to organize high-voltage line conductors. Finally, to demonstrate the financial applicability of the solution, comparison is held between the cost of rearranging transmission line conductors and the cost of non-reducing the fields, based on a survey for people living near high voltage line in the populated city of Irbid in Jordan. Although the operating frequency for the examples in this paper is 50 Hz, the algorithm can be used for other power frequencies such as 60 Hz. The solutions are 2D, where infinite line length is assumed. Also, the algorithm uses the recommended exposure limits of 0.4 µT for the magnetic field and 5 kV/m for the electric field.

This article presents a compact, low profile, four ports multiple-input-multiple-output (MIMO.) antenna operating at the n38 and n41 5G frequency bands. The antenna has a measured -10 dB bandwidth of 2.5-2.9 GHz with isolation less than -11 dB. The designed antenna system employs open slot radiators etched on a single-sided rectangular PCB substrate with a total size of 40 ×100 mm², including a ground plane. The open slot radiators are symmetrically printed at the four corners of the rectangular substrate. The radiators are excited by 50-Ω strip lines. Rectangular-shaped slits are used as decoupling structures. MIMO parameters such as the envelope correlation coefficient (ECC), channel capacity loss (CCL), and mean effective gain (MEG) are being calculated using the measured results. The ECC is less than 0.1 over the entire operating band despite the antenna's small size. The proposed antenna shows good performance in two sub-6-GHz frequency bands for 5G NR applications: n38 (2570 to 2620 MHz) and n41 (2496 MHz-2690 MHz).

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.