Advanced Electromagnetics (E-Journal)
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Modeling a Planar Coupled Microstrip Lines using various Wavelets and Method of Moments
No full textIn this paper, we apply a several wavelets basis functions to the method of moments to modeling the parallel-coupled microstrip lines. The first set of equations is for the shielded microstrip line solved with moment’s method and wavelets. The Green’s function is obtained from the theory of images. The second set are for the parallel-coupled microstrip lines operating in the TEM mode or when the analysis can be based on quasi-static approximation, the properties of coupled lines can be determined from the self- and mutual inductances and capacitances for the lines. To demonstrate the effectiveness and accuracy of the proposed technique, numerical results of even- and odd-mode characteristic impedances, coupling coefficient, percentage sparsity achieved in the impedance matrix, the CPU Time to reverse impedance matrix, and error relative for Daubechies, Coiflets, Biorthogonal and Symlets wavelets are presented. Numerical results are in good agreement with those in previous publications
Analysis of Current Distributions and Radar Cross Sections of Line Source Scattering from Impedance Strip by Fractional Derivative Method
No full textIn this paper, we have studied the analysis of current distributions and radar cross sections of line source scattering from impedance strip. The problem was solved with fractional derivative method previously. Here, the specific case of fractional derivative method is investigated. The problem under consideration on the basis of various methods is studied well, however, they are mainly done by numerical methods. The fractional derivative method, allows an analytical solution in a specific situation. This method allows to obtain analytical solution of impedance strip for a special case which is fractional order is equal to 0.5. When fractional order is 0.5, there is an analytical solution which is explained and current distribution, radar cross section and near field patterns are given in this paper. Here, as a first time, current distribution, bi-static radar cross section and near field for the upper and lower part of the strip are studied
Lightning Response of Multi-Port Grids Buried in Dispersive Soils: An Approximation versus Full-wave Methods and Experiment
No full textIn this paper, application of multi-conductor transmission line model (MTL) in transient analysis of grounding grids buried in soils with frequency-dependent electrical parameters (dispersive soil) is investigated. In this modeling approach, each set of parallel conductors in the grounding grid is considered as a multi-conductor transmission line (MTL). Then, a two-port network for each set of parallel conductors in the grid is then defined. Finally, the two-port networks are interconnected depending upon the pattern of connections in the grid and its representative equations are then reduced. Via solving these simplified equations, the transient analyses of grounding grids is efficiently carried out. With the aim of validity, a number of examples previously published in literature are selected. The comparison of simulation results based on the MTL shows good agreement with numerical and experimental results. Moreover, in despite of numerical methods computational efficiency is considerably increased
Analysis of the Effect of a Gyrotropic Anisotropy on the Phase Constant and Characteristic Impedance of a Shielded Microstrip Line
No full textIn this work, we present an analytical modeling of a highly complex medium-based shielded microstrip line. The study aims at a numerical evaluation of the characteristic impedance and the dispersion characteristics of the dominant hybrid mode in the microstrip line printed on an anisotropic medium. The newly considered complex anisotropy has a full 3×3 tensor form of permittivity and permeability. The study is based on the derivation of the Green's functions of the general complex-medium-based structure in the Fourier domain. The spectral Method of Moments (MoM) and the Galerkin's procedure are combined to solve the resulting homogeneous system of equations. The effect of the gyrotropic anisotropy on the phase constant and the characteristic impedance is particularly investigated. Original and interesting numerical results are obtained and discussed. Our results are found to be in good agreement with available isotropic case data reported in literature
The Prototype of a Wideband Ku-Band Conical Corrugated Horn Antenna with 3-D Printing Technology
No full textThis study is about the design and production of a conical corrugated horn antenna used to feed reflector antennas in satellite communication (direct broadcast satellite-DBS) systems. The antenna designed with CST Microwave Studio program operates within wideband of 10.5-18.5 GHz at Ku-band. The prototype is realized with new generation 3D printing technology and conductive paint coating method, which makes the antenna lightweight and provides low cost and faster production. According to measurement results, the antenna has return loss almost better than 20 dB, gain value of minimum 14.5 dBi and sidelobe level of -18 dB at most within 1.76:1 frequency bandwidth. Antenna is observed to have a gain loss of at most 1.5-2 dB within the band as compared to the same antenna with high conductivity metal, which needs higher cost and production time for the manufacturing
A Compact Multi-Band Monopole Antenna using Metamaterial for WLAN/WiMAX Applications
No full textIn this paper, a tri-band printed monopole antenna with electrically coupled metamaterial units is proposed and investigated. The proposed antenna is designed to cover WLAN/WiMAX applications. The antenna consists of a printed strip line and two double metamaterial unit cells of different size placed near the monopole antenna on opposite sides. Each unit cell exhibits a negative permeability over the resonance frequency at 2.5 GHz and 3.62 GHz, which produces magnetic couplings with the monopole antenna. The proposed antenna structure was fabricated and measured. The measured -10 dB bandwidth for the return loss is from 2.47GHz-2.51GHz, 3.59GHz-3.69GHz, and 5.3GHz - 7.2 GHz, which are suitable for (WLAN: 2.4–2.484, 5.15–5.35, and 5.725–5.85 GHz) and (WiMAX: 2.5–2.69, 3.4–3.8, and 5.25–5.85 GHz) band Applications. By using the switches across the gap of proposed-MTM unit cell, the effect of this unit deactivated and its resonance frequency will disappear. Hence, the proposed antenna maintains the omnidirectional radiation pattern
A High-Power Microwave Reflectarray Antenna Based on Perforated Dielectric Substrate
No full textA high power microwave antenna based on the reflectarray concept is designed and investigated in this paper. The reflectarray aperture is directly driven by an azimuthally symmetric mode and a directional boresight beam is realized through azimuthally introducing a phase shift of 90 to the phase shift profile of reflectarray unit cells. A sample model operating at X-band is designed to verify the validity of the proposed approach. Variable diameter air-filled holes through a host dielectric material are exploited as the phase-shifting unit cells because of the advantage of higher power handling capacity. Theoretical analysis and full-wave simulations are accomplished and results are in good agreements. A collimated beam of circular polarization with peak gain of 20.2 dB and axial ratio of 1.3 are achieved at the boresight direction for the design frequency of 10 GHz. The radiation performance of the proposed antenna as well as its compact structure makes it a potential candidate for high gain high power applications
Wideband Microstrip Dipole Antenna Design for WLAN/WiMAX Applications
No full textRecently, microstrip antennas are preferred in all areas of wireless communication, due to their advantages such as low volume coverage, light weight, surface compatibility, high cost requirements and easy production etc. The main disadvantage of these antennas is their narrow band performance (~11%). In the literature, there are some wideband microstrip antenna designs. These broadband characteristics are obtained by changing the antenna geometry or by adding new parasitic patches to the antenna elements. In this study, a classical wideband microstrip dipole antenna (MDA) design which can be used in WLAN/WiMAX applications (covering the bands 2.4–2.5 GHz and 2.5–3.5 GHz) is introduced. The proposed antenna has a pair of twisted strip which are placed asymmetrically near the feed of the dipole element with a length of 52 mm (~λ/2). Also a pair of square loop elements is placed on a sublayer. The proposed MDA has a resonance between 2.06-3.72 GHz with a bandwidth of 57%. The antenna has a directive radiation pattern with a gain of 6.49-3.98 dBi
A Low Profile Wideband Log Periodic Microstrip Antenna Design for C-Band Applications
No full textIn this study, a wideband low profile microstrip antenna design for C-band applications is presented. The proposed antenna consists of a monopol log periodic patch in the equilateral triangular dimensions with the microstrip line fed and a rectangular ground plane. The antenna has 9×19.8 mm2 overall size, thickness of 1.6 mm and 4.3 dielectric constant. According to the simulation results, the proposed antenna has a very wide bandwidth while operating in the frequency band of 4.25-7.95 GHz and 5 GHz resonance frequency. The proposed antenna was also prototyped on FR4 substrate with the 0.02 tangent loss and the measurement results were quite similar by the simulated results
An Accurate and Compact High Power Monocycle Pulse Transmitter for Microwave Ultra-Wideband Radar Sensors with an enhanced SRD model: Applications for Distance Measurement for lossy materials
No full textIn This paper, a high power sub-nanosecond pulse transmitter for Ultra-wideband radar sensor is presented. The backbone of the generator is considered as a step recovery diode and unique pulse injected into the circuit, which gives rise to an ultra-wide band Gaussian pulse. The transistor driver and transmission line pulse forming the whole network are investigated in detail. The main purpose of this work is to transform a square waveform signal to a driving pulse with the timing and the amplitude parameters required by the SRD to form an output Gaussian pulse, and then into high monocycle pulses. In simulation aspect, an improved output response is required, in this way a new model of step recovery diode has been proposed as a sharpener circuit. This proposition was applied to increase the rise-time of the pulses. For a good range radar, a high amplitude pulse is indispensable, especially when it comes to penetrate thick lossy materiel. In order to overcome this challenge, a simple technique and useful solution is introduced to increase the output amplitude of the transmitter. This technique consists to connect the outputs of two identical pulse generators in parallel respecting the restrictions required. The pulse transmitter circuit is completely fabricated using micro-strip structure technology characteristics. Waveforms of the generated monocycle pulses over 10V in amplitude with 3.5 % in overshoot have been obtained. Good agreement has been achieved between measurement and simulation results