This paper presents two size-miniaturized quarter mode (QM) and eighth mode (EM) substrate integrated waveguide (SIW) bandpass filters (BPFs), which are embedded with a novel frequency-dependent coupling (FDC) structure. The proposed FDC is implemented as a composition of balanced folding lines and inductive iris. One additional transmission zero (TZ) introduced by FDC between two cavities leads to higher frequency selectivity and better out-of-band rejection. Higher order modes suppression appears by combining the loaded paired open stubs on feeder lines with FDC technique, achieving a wide stopband. Meanwhile, the circuit dimension is further reduced by symmetrically cutting SIW. To validate the novel approach, the frequency-dependent coupling matrix (CM) is implemented to determine characteristics of the proposed structure in theory, QM- and EM-SIW BPFs loaded with FDC have been designed, fabricated and measured. Experimental results illustrate the characteristics of miniaturization and good performance. All results are in good agreement.

In this research project, the hardware implementation of a Field-Programmable Gate Array (FPGA) based Fast Fourier Transform (FFT) will be carried out by using Verilog Hardware Description Language (HDL). Since FFT serves as the core for the Range Doppler Algorithm (RDA) in Synthetic Aperture Radar (SAR) processing, it is of paramount importance to evaluate the algorithm and its computational complexity for the design of an efficient FFT hardware architecture. The design process and Verilog hardware description language which is used to describe and model a digital FPGA-based SAR processor will be introduced. Detailed explanation of the hardware implementation for FFT and Inverse Fast Fourier Transform (IFFT) in SAR processing are thus presented. The performance evaluations of the proposed processors including the comparison of the proposed processor with MATLAB-based processor, timing considerations of the processor, and lastly the hardware resources usage considerations are delivered at the end of this paper.

In this paper, new fractal curves are designed, simulated, and implemented for passive UHF RFID application. 5-, 6-, 7-, and 8-sides polygon fractal loops are proposed and implemented in this work based on the 2nd iteration. It is shown that increasing the number of sides can improve the performance and minimize the size of the fractal antenna. The designed fractal loop antennas have been compared with other fractal loop antennas published previously, and the recent antennas show a better performance. The designed antennas are fabricated using PCB technology, and the antenna parameters are measured experimentally and compared to CST simulations. There is an acceptable agreement between the simulated and measured results. The effect of different materials on antenna performance is also studied.

In this paper, the performance analysis of a dual-hop reconfigurable intelligent surface (RIS)-aided power line communication (PLC) system is presented under different relay transmission protocols. The relay is assumed to be decode-and-forward (DF) or amplify-and-forward (AF) relaying protocol. It is also assumed that the RIS link is subjected to Rayleigh fading while the PLC link undergoes Log-normal fading with the influence of additive background and impulsive noise. To evaluate the system performance, the end-to-end cumulative distribution function for both relaying protocols are derived. Based on these, the analysis expressions for the system outage probability and average bit error rate (ABER) are derived under DF and AF relaying protocols. To gain further insight about the system performance, the asymptotic analysis for the derived expressions is obtained at high signal-to-noise ratio regime. The findings illustrate the significant impact of the number of RIS elements and impulsive noise on the overall system performance. In addition, the accuracy of the analytical results is justified through Monte-Carlo simulations.

By combining the method of moments and the compressive sensing theory, a rapid scheme for analyzing the electromagnetic scattering problems over a wide incident angle has been developed, by which the calculation times of traditional method of moments can be decreased efficiently. To further reduce the calculation times, the matrix splitting technique is proposed to establish a new scheme in this paper. The basic principle is elaborated in detail, and the effectiveness of the new scheme is verified by numerical results.

A non-invasive thermometry approach for monitoring core (internal) tissue temperature using microwave radiometry is presented. We detail the design and analyses of a microwave antenna capable of detecting core temperature at depth. Performance of the radiometer with a printed dipole antenna is evaluated at frequency of 1.4 GHz in a multilayer 3D computational structure consisting of skin, fat, and muscle. To study this approach, a human tissue model was constructed with skin, fat, and deep muscle tissues having electrical properties at working frequency of 1.4 GHz. One of the main challenges is the Radio Frequency (RF) interface; hence, frequency selection will be important. Moreover, the antenna must be designed for characteristics in close proximity of biological medium in the selected frequency band. The Specific Absorption Rate (SAR) and volume loss density have been used to determine the amount of absorbed power in each tissue layer and thus emitted power from each tissue layer. This approach has been designed to detect thermal emissions radiated from tissue up to 23 mm deep. We present the numerical analysis of 3D tissue-layer power emission and temperature sensing by a microwave radiometric antenna from a single frequency band of 1.4 GHz. Computed results show that this method senses the internal temperature in each tissue layer.

In this article, we present a compact and efficient diametrically-fed dual port fractal UWB MIMO antenna for portable handheld wireless devices. The electromagnetic behaviour on conducting body is analyzed through classical approach based characteristics mode analysis (CMA). Their intrinsic characteristics are explored on the basis of (a) modal surface current distributions, (b) narrow/broad bandwidth capability and (c) radiation potentials. Concurrent analysis is persuaded on diametrically-fed dual port fed fractal conducting surface, that provides interesting facets on the combinatory effect of electromagnetic performance and physical behaviour on metallic radiator, metallic ground planes (unconnected/connected) and combination of two aforementioned metallic compact geometries. Theoretical insights are investigated for essential/non-essential modes existing in proposed geometry. The investigation through CMA also gives plethoric information on the feed location of antenna on modal surface currents and similar trends to capture its radiation potentials on the current nulls existing in the physical body. A broad classification of modes is explained, covering the CMA modal dynamics such as (a) characteristics angle (CA), (b) eigen values (EV) and (c) modal significance (MS). These additive parameters in general reflect the resemblance of Q-factor≈B.W. for narrowband/wideband traits, electrically/magnetically coupled energy behaviour and radiative potential for far-field propagation. Thus, in a nut-shell, it can be inferred that `CMA provides physically intuitive guidance for the analysis and designing of antenna structures'. To support the findings highlighted in this particular study, a concise review about the theory of characteristic modes and the practical examples that use such concepts are taken into consideration.

A novel circularly polarized (CP) square slot antenna for covering the universal ultrahigh-frequency (UHF) radio frequency identification (RFID) band is proposed. The antenna uses low-cost FR4 material as the dielectric substrate and coplanar waveguide (CPW) to feed. Circularly polarized radiation can be realized by embedding two symmetrical rectangular grounded planes with L-shaped slits in opposite corners of the square slot. The widened vertical tuning stub at the end of the signal line fed by CPW can improve the CP and impedance matching operation, and finally realizes broadband characteristic. The measured 10 dB impedance bandwidth and 3 dB axial ratio (AR) bandwidth are 1250 MHz (710-1960 MHz) and 180 MHz (840-1020 MHz), respectively. The measured peak gain is about 3.4 dBi in the whole UHF RFID frequency band (0.84-0.96 GHz). The dimension of the CP square slot antenna is 116×116 ×1.6 mm³. The proposed antenna has the advantage of simple structure, is easy to be processed, can exhibit dual CP radiation characteristic, and covers the broadband frequency range, which can be applied to the UHF RFID handheld reader environment.

This paper presents an online noise source impedance extraction method based on network analyzer. Firstly, the composition scheme of the measurement method is given, the equivalent circuit model of the measurement system established, and the port structure of the equivalent circuit analyzed. Secondly, two known standard resistances are used to calibrate the measuring system and connecting wires. Finally, the passive device and DC/DC converter are used as the equipment to be tested, and the measurement results are compared with those of other methods and impedance analyzer. The comparison results show that the measurement method has high measurement accuracy and good temperature sensitivity.

Enhancing the electromagnetic absorption properties of pozzolanic cement provides scope for low cost realisation of frequency screened buildings. Electromagnetic wave attenuation attribute of conductive filler inclusions determines the absorption properties of filler loaded cement mortar. A transmission line based rapid measurement technique for the speedy estimate of microwave attenuation of conductive fillers is presented, providing quick approximates of cement mortar thickness for realizing customized absorption loss. Ash from three units of steel plant including EAF, AoD, and ARS units is investigated. Coaxial transmission line supports TEM propagation, hence is well suited for estimating plane wave characteristics. Ash filled coaxial transmission structures are subjected to scattering matrix measurements in the frequency range 800 MHz-4 GHz. Plane wave attenuation is estimated from the scattering matrix transfer coefficient (S₂₁). Ashes guarantee minimum 10 dB/m attenuation in the specified frequency range with ash from ARS unit providing loss over 50 dB/m. The database of customized cement mortar (composite) thickness for realizing varied absorption losses, incorporating ARS ash, is projected. The presented technique reduces the requirement of anechoic chambers, broad band horns, and liability of prototyping large mortar samples (all frequency dependent), for estimating shielding properties of conductive filler loaded cement mortar composites, over wide band. Cement panels with customized absorption loss provide scope as low cost solution for managing device co-location issues encountered in evaluating EMI/EMC concerns is future IoT based systems.

In this article, a novel idea of designing a graphene based planar plasmonic patch antenna for terahertz wireless applications with detailed analysis is proposed. Based on the Surface Plasmon Polariton Waves (SPP) behaviour in graphene, a novel wideband planar graphene-based patch antenna is investigated here. As graphene with its wondered properties supports SPP in much lower infrared frequencies unlike the noble metals such as gold and Nickle which support SPP at much higher frequencies, the proposed planar antenna works on THz gap (0.1-10 THz) by covering a range of frequencies from 0.1 THz and goes beyond 10 THz, thus covering the whole THz gap. The proposed antenna is a simple planar structure with overall size of 31.8 x 6.4 μm² having a Silicon with a relative permittivity (ε_r) of 11.9 used as a substrate material, and simple plane wave is used for excitation. Furthermore, radiating material comprises single layer graphene and copper with a partial ground of copper material, and for comparison purpose, only graphene layer as a radiating material is also analysed. Single layer graphene conductivity having chemical potential of 0.4 ev, relaxation time of 0.6 ρs, and a temperature of 298 K is discussed. Parametric analysis for getting optimum results is also studied. The unity peak absorption of above 98% is observed throughout the resonating frequency range. The proposed design is numerically simulated in CST MWS v2020, and other parameters results, such as unity peak absorption and surface current, are also discussed.

This paper presents a miniaturized antenna-based wearable self-powered wireless systems; the proposed study identifies the possibility to compact a flexible Solant-Rectenna integrated to low energy devices. The proposed system uses the obtained DC currents from RF rectifier and solar panel to recharge batteries. A low-profile Hilbert-shaped metamaterial (MTM) array forming a rectangular patch is conducted to minimize the shadowing effects to 13.3% on the solar panel area. Nevertheless, an Electromagnetic Bandgap (EBG) square pads array is introduced as defects on the ground plane to remove the negative effects, in terms of losses, of the solar panel bus-bar on the antenna performance. Moreover, the proposed EBG ground plane is utilized to isolate the human body from the undesired electromagnetic radiation leakage in addition to minimize the antenna impedance mismatch caused by the proximity to human tissues. For this, the Specific Absorption Rate (SAR) is analysed numerically to assess the feasibility of the proposed EBG layer. The antenna expresses a frequency bandwidth, S₁₁ < -10 dB, from 0.8 GHz up to 10 GHz; moreover, the EBG inclusions increase the front to back ratio to provide the gains of -10 dBi, -4 dBi, 0 dBi at 0.915 GHz, 1.88 GHz, and 2.45 GHz, respectively. Moreover, a SAR reduction is achieved up to 64% down after the EBG layer introduction. In addition, the antenna distortion effect in terms of group delay (G_d) after 3.1 GHz up to 10 GHz is tested; the maximum variation is found to be less than 1ns which shows a linear phase response with distortionless waveforms. Such a feature is found very suitable for UWB applications in modern wireless systems. The antenna performance improvement after introducing the proposed EBG defects is validated experimentally and numerically. The solar panel I-V characteristics are measured after the antenna structure introduction. Next, the solant RF port is connected to a rectifier circuit to realize the rectenna performance port that collects the RF energy at three bands in terms of efficiency spectra. Finally, it is proofed that the proposed Solant-Rectenna offers an excellent, compacted, and flexible candidate for the wearable self-powered devices at different bands.

In this article, the diffraction of E-polarized electromagnetic plane waves by a double half-plane structure is taken into account. The shift of the upper half-plane through the horizontal axis for different wavenumber and boundary conditions are considered. On the double half-plane structure, fractional boundary conditions are required on the half-plane surfaces. The half-planes are parallel to each other with a variable shift in distance and location. The formulation of the problem is given where the boundary condition is explained, and the integral equations for each half-plane are obtained by using fractional calculus and Fourier Transform techniques. Then, for numerical calculations, the induced current on each half-plane is expressed as the summation of Laguerre polynomials. This leads to having a system of linear algebraic equations needed to be solved. The numerical results show that the shift and the distance between the half-planes give a very important effect on the field values inside and outside the guiding structure. The results are compared and analyzed with Method of Moment and previous results.

The capacitance matrix relates potentials and charges on a system of conductors. We review and rigorously generalize its properties, block-diagonal structure and inequalities, deduced from the geometry of system of conductors and analytic properties of the permittivity tensor. Furthermore, we discuss alternative choices of regularization of the capacitance matrix, which allow us to find the charge exchanged between the conductors having been brought to an equal potential. Finally, we discuss the tacit approximations used in standard treatments of the electric circuits, demonstrating how the formulae for the capacitance of capacitors connected in parallel and series may be recovered from the capacitance matrix.

A multiband microstrip antenna is designed for wireless communication application with fractal and defected ground structures. Antenna prototype is fabricated using Rogers RT Duroid 5880 dielectric material on a double layer PCB with dielectric constant 2.2 and thickness 0.8 mm. Through implementing the concept of elliptical shape fractal geometry to microstrip patch antenna, more miniaturization is achieved. Further with defected ground structures, wide impedance bandwidth and gain are achieved. A compact microstrip feedline is used to couple electromagnetic energy to radiator through lumped port. Proposed antenna shows multiband characteristics. Antenna resonates at 2.6 GHz, 6 GHz and 8.2 GHz frequency bands with impedance bandwidth of 410 MHz, 1070 MHz and 4840 MHz. Experimental validation is done to validate simulation results. Antenna operates on different wireless standards like Wi-Fi (2.4 GHz), WLAN (2.4/5.2/5.8 GHz), Wireless Body Area Network (2.3/2.4 GHz), which falls under ISM (Industrial Scientific and Medical) band applications. It also covers communication bands, X-band (8-12 GHz) and S-band (2.3-2.4 GHz).

A conformal circularly polarized UHF antenna integrated on the body of a CubeSat is presented. The antenna operates at 485 MHz and provides at least 10 MHz impedance bandwidth. Traditional UHF antennas for CubeSat have been wire or tape measures that require mechanical deployment, whereas the antenna reported in this paper does not need such treatment and therefore has a potential application in CubeSat mission by promising a more reliable communication link and reduced cost. The measurements showed good agreements with the design data, validating frequency response, bandwidth, and circular polarization level of the proposed antenna.

This article presents the design and development of a low profile substrate integrated waveguide semi-circular cavity-backed antenna loaded with dielectric cylinders of glass-reinforced epoxy and Teflon. The substrate integrated waveguide semi-circular cavity-backed antenna without dielectric loading radiates at 5.8 GHz with 3.13 dB gain. The antenna is modified by putting dielectric cylinders of different materials and different sizes at the edge of a semi-circular cavity to enhance the gain of the antenna. The new antenna thus created has improved gain of 8.13 dB. All simulations are done using high frequency structure simulation software. The proposed design is fabricated on a glass-reinforced epoxy substrate with a semi-circular cavity having a size of 60 mm x 50 mm. The measured results are in good agreement with simulated ones.

The Ricean probability density function (pdf) is widely used to estimate the electromagnetic field distribution in indoor environments. The goal of using the Ricean or other pdfs is to evade the computational cost of deterministic field calculation. The parameters of the pdfs are usually obtained using the maximum-likelihood estimation which is here shown to fail in local areas close to the antenna where the direct field varies significantly. This paper presents the new localized maximum likelihood method which is valid in close regions as well. Moreover, the maximum-likelihood method requires a large number of field values within the local area to yield the parameters of the pdf. This paper presents the ray-tracing maximum-likelihood (RTML) method where a much lower number of field values are required. These values are determined using ray-tracing and without the need to account for the computationally expensive higher-order reflections. The RTML fails in local areas close to the antenna, and thus the new localized RTML is presented to restore accuracy.

In the gyrotron traveling wave amplifier (gyro-TWA), high loss dielectric materials loaded in a cylindrical waveguide are adopted to suppress the unwanted parasitic oscillations. It is of great importance to accurately understand the relative permittivity ε_r and tanδ for studying the microwave and millimeter wave dispersion, and loss properties of a specific mode. The high lossy dielectric loaded circuit of the gyro-TWAs made of the BeO-SiC ceramic with certain relative permittivity and loss tangent are theoretical calculated, simulated and measured. The field distribution, dispersion and loss properties of three different dielectric loaded circular HE^d₁₂, HE^d₂₂ and TE^d₀₂ modes (corresponding to the TE₁₁, TE₂₁ and TE₀₁ modes in the smooth hollow cylindrical waveguide respectively) in different frequency bands are respectively investigated. The theoretical analysis, simulation, and measurement results have a good agreement. This work has clear guiding significance for the stable work of gyro-TWAs.

In this paper, using binary phase-shift keying (BPSK) modulation, analytical expressions of bit-error-rate (BER) for various non-homogeneous fading environments (α-μ, η-μ and κ-μ) subjected to SαS noise are obtained. The derived results are expressed in terms of Meijer's G-function and Gamma function. These expressions are used to study the performance of other prominent fading models (like Nakagami-m, Rayleigh, Rician, and Hoyt) available in the technical literature. Further, it is shown that the effect of the impulsive index (α) over BER is much pronounced compared to the amount of fading (AF). Numerical results are provided for different impulsive settings. The derived results corroborate with simulations.