Advanced Electromagnetics

A New Approach to the Analysis of Electromagnetic FEM Simulations Results at Electric Field Singularities

G. Betti Beneventi, M. DalRe, L. Vincetti — Wed, 19 Sep 2018 13:48:27 -0400

A new methodology to the analysis of the results of Finite-Element Modeling (FEM) simulations at electric field singularities is proposed. The method, that can be easily applied in the post-processing phase of the electromagnetic FEM analysis workflow, is based on the weighted averaging of the calculated electric field magnitude within small volumes including the singularity point under investigation. In the paper, the proposed approach is applied to the electrical stress analysis of a high-voltage device modeled by means of a commercial electromagnetic FEM tool. In comparison to the conventional metric of the maximum field evaluation usually adopted for the analysis of electrical stress in insulators, our approach features several advantages: (i) the outcome of the analysis is independent of the numerical grid refinement at the singularity, thus allowing direct comparison of calculated electric field with the material dielectric strength; (ii) the method is robust against slight modifications of the geometrical shape of the singularity; (iii) on the other hand, for a given shape, the analysis outcome responds to significant variations of the singularity size or, in other words, of its sharpness; (iv) in the analysis of highvoltage devices, the approach can be applied for the estimation of the discharge volumes corresponding to different singularity types of different device geometries. In the paper, the new methodology is explained in details and is applied to simple but significant case studies.

Iterative Scattering by Two PEMC Elliptic Cylinders

A.-K. Hamid — Wed, 19 Sep 2018 07:18:24 -0400

Iterative procedure is implemented to derive rigorous solution to the problem of plane electromagnetic wave scattering by couple of perfect electromagnetic conducting (PEMC) elliptic cylinders due co and cross polarized scattered fields among cylinders. The translation addition theorem for Mathieu functions is enforced to compute the higher order scattered fields by single PEMC elliptic cylinder in terms of the other elliptic cylinder coordination system to impose the boundary conditions. The kth co and cross polarized scattered field coefficient expressions are extracted by iteration procedure without using matrix inversion.

Comparative Study of the Accuracy of Analytical Inductance Formulae for Square Planar Spiral Inductors

H. A. Aebischer — Wed, 19 Sep 2018 00:00:00 -0400

In the design of radio frequency (RF) microelectronic integrated circuits (IC’s) and of antennas for short-wave radio frequency identification (RFID) and telemetry systems, planar spiral coils are important components. Many approximate analytical formulae for calculating the inductance of such coils can be found in the literature. They can simplify the problem of designing inductors to a predefined inductance considerably. But the error statistics given by different authors cannot be compared because they are based on different or unknown domains of definition. Hence, it is not possible to decide which formula is best in a given case by merely studying the literature. This paper compares the maximum relative errors of six of some of the most cited formulae in the literature. To all formulae, the same domains of definition are applied. Each of them spans all four dimensions of the parameter space. Precise inductances are obtained numerically with the help of the free scientific and industrial standard software FastHenry2 and used as reference values to calculate the errors of the formulae. It has been found that the alleged maximum errors reported by some authors are far too optimistic. Only two formulae feature small enough errors to be useful in circuit design. The method and the domains of definition applied in the present study may also prove useful for the assessment of future formulae.

Broadband Koch Fractal Boundary Printed Slot Antenna for ISM Band Applications

V. V. Reddy — Wed, 05 Sep 2018 06:43:42 -0400

A new broadband radiating slot antenna with fractal shape is modeled, fabricated and experimentally studied. The presented slot antenna is examined for first three iterations. Optimization of iteration factor (IF) and iteration angle (IA) have been done for each iteration order (IO) to enhance impedance bandwidth significantly. All the antennas are fed with a simple microstrip line. Bandwidth achieved with Antenna 1 (IO=1, IF=0.35 and IA=60⁰) is 1550 MHz which is five times more than that of the square slot antenna. The performance of the proposed fractal slots is also compared with the rotated slot antenna. The experimental data validates the reported analysis with a close agreement.

Triple band Compact Fractal Antenna with Defected Ground Plane for Bluetooth, WiMAX, and WLAN Applications

M. Harbadji, A. Boufrioua, T. A. Denidni — Wed, 05 Sep 2018 06:22:06 -0400

This paper presents a novel compact coplanar waveguide (CPW) monopole fractal-shaped antenna using fractal patch composed of hexagons with defected ground plane. Inclusion of a pair of S-shaped slots on the ground plane is used to extend the antenna impedance bandwidth and to provide multiband operation. The antenna has a compact size of 35×35×1.27 mm³which is compact. The antenna is designed, fabricated and measured. Good performances in terms of return loss, gain and radiation pattern are obtained in the operating bands, which makes the proposed antenna a good candidate for multiband wireless systems. The obtained results show that the antenna operates at Bluetooth,Worldwide Interoperability for Microwave Access (WiMAX), and Wireless Local Area Network (WLAN).

Characteristics UWB Planar Antenna with dual notched bands for WIMAX and WLAN

M. Debab, Z. Mahdjoub — Wed, 05 Sep 2018 05:47:34 -0400

In this article, a novel design of ultra wideband monopole antenna with dual notched bands performance is proposed. The size of the UWB antenna is minimized to 20 -17.6mm² , printed on FR4 substrate 1.5 mm thickness and loss tangent tan𝛿 =0.02, and is fed by coplanar waveguide. The operation bandwidth of the designed antenna is from 3.1 GHz to more than 10 GHz. Band notches characteristics of antenna to reject the frequency band, WIMAX Band and WLAN Band, is realized by cutting three quarter wavelength slots in the radiating patch. A quarter wavelength slot in the radiator of the antenna is used to create a frequency band notch at the WIMAX frequency band. However, the WLAN frequency band is notched using two symmetrical quarter wavelength slots. The proposed antenna is simulated using HFSS and CST high frequency simulators. These results are compared with measured results by using network analyzer.

A New Lowpass Filter Unit Cell with Sharp Roll-off and Improved Stopband Performance in Coplanar Waveguide Technology

A. Bijari, M. Mohebrad — Tue, 04 Sep 2018 07:39:30 -0400

In this paper, a new compact unit cell for a coplanar waveguide (CPW) lowpass filter (LPF) is proposed. By combining a pair of coupled parallel stepped impedance resonators (SIRs) and high impedance short stubs in the CPW line, a fifth-order elliptic lowpass filter unit cell (LUC) is designed. The extra transmission zero introduced by parallel coupled SIRs is used to extend the stopband and increase the roll-off rate. The characteristics of the proposed LUC is investigated to achieve a sharp roll-off and a wide stopband. The measured results are in accordance with the simulated results. It has an insertion loss less than 0.9 dB from dc to 6 GHz, and a wide -15 dB stopband from 7.5 to 18 GHz. In addition, the filter dimensions are as small as 4.9 mm × 8.7 mm, that is, 0.046λ_g², where λ_g is the guided wavelength at the cut-off frequency. The filter structure is simple and easy to fabricate as well.

Miniaturized Wideband Microstrip Antenna for Recent Wireless Applications

S. A. Shandal, Y. S. Mezaal, M. F. Mosleh, M. A. Kadim — Tue, 04 Sep 2018 06:55:56 -0400

In this paper, a pentagon slot inside fractal circular patch microstrip resonator to design compact antenna over partial ground plane is introduced using 3^rd iteration of adopted fractal geometry. This antenna is modeled on FR4 substrate with a size of (20 x 18) mm², thickness of 1.5mm, permittivity of 4.3 and loss tangent of 0.02. The used type of feeding is microstrip line feed. It is designed to operate at wide frequency range of (4.5-9.3) GHz at resonant frequencies of 5.7GHz and 7.9GHz with impedance bandwidth of 4.8 GHz. Both lengths of ground plane L_g and width of feed line W_f are optimized in order to acquire optimum bandwidth. The simulated return loss values are -33 and -41 dB at two resonant frequencies of 5.7 and 7.9 GHz with gain of 3.2 dB. The simulated results offered noteworthy compatibility with measured results. Also, the proposed wideband microstrip antenna has substantial compactness that can be integrated within numerous wireless devices and systems.

Circularly Polarized Split Ring Resonator Loaded Slot Antenna

A. R. Parvathy, V. G. Ajay, M. Thomaskutty — Tue, 04 Sep 2018 06:49:30 -0400

A compact circularly polarized printed slot antenna operating at 2.45 GHz is reported. The antenna consists of a pair of rotated square split ring resonators (SRR) inside a rectangular slot etched on the ground plane of an FR-4 dielectric substrate. A microstrip open-loop feed is etched on the backside of the dielectric substrate to feed the slot and the split ring resonators. The overall size of the antenna is 60x42x1.6 mm3. The measured -10dB impedance bandwidth is 10.48% (2.38-2.64 GHz) and the measured 3dB axial ratio (AR) bandwidth covers the entire impedance bandwidth.

A Novel LS/LMMSE Based PSO Approach for 3D-Channel Estimation in Rayleigh Fading

D. N. Bhange, C. Dethe — Tue, 04 Sep 2018 06:36:42 -0400

A high transmission rate can be obtained using Multi Input Multi Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) model. The most commonly used 3D-pilot aided channel estimation (PACE) techniques are Least Square (LS) and Least Minimum Mean Square (LMMSE) error. Both of the methods suffer from high mean square error and computational complexity. The LS is quite simple and LMMSE being superior in performance to LS providing low Bit Error Rate (BER) at high Signal to Noise ratio (SNR). Artificial Intelligence when combined with these two methods produces remarkable results by reducing the error between transmission and reception of data signal. The essence of LS and LMMSE is used priory to estimate the channel parameters. The bit error so obtained is compared and the least bit error value is fine-tuned using particle swarm optimization (PSO) to obtained better channel parameters and improved BER. The channel parameter corresponding to the low value of bit error rate obtained from LS/LMMSE is also used for particle initialization. Thus, the particles advance from the obtained channel parameters and are processed to find a better solution against the lowest bit error value obtained by LS/LMMSE. If the particles fail to do so, then the bit error value obtained by LS/LMMSE is finally considered. It has emerged from the simulated results that the performance of the proposed system is better than the LS/LMMSE estimations. The performance of OFDM systems using proposed technique can be observed from the imitation and relative results.