Home > All Issues > PIER C
ISSN: 1937-8718

Vol. 115

Latest Volume
All Volumes
All Issues

2021-10-09 PIER C Vol. 115, 277-289, 2021. doi:10.2528/PIERC21072305

Artificial Neural Network Based SIW Bandpass Filter Design Using Complementary Split Ring Resonators

Ranjit Kumar Rayala and Singaravelu Raghavan

A novel Artificial Neural Network (ANN) based two Substrate integrated waveguide (SIW) bandpass filters comprising Complementary Split Ring Resonators (CSRRs) are proposed in this paper. These CSRRs are modelled on the upper layer of the SIW cavity. A feed forward multilayer perceptron (FF-MLP) neural network is used to optimize the physical dimensions of the proposed filters. To validate the analytical results, physical prototypes of the proposed filters are fabricated, and a measurement is carried out with a Combinational Network Analyzer (Anritsu-MS2037C), and the obtained experimental results agree well with the estimated results using full wave analysis. Within the passband from 8.22 to 8.95 GHz, S12 of the first filter shows better than -0.5 dB insertion loss (IL) and a fractional bandwidth of 8.5%, and within the passband from 8.21 to 8.73 GHz, the second filter shows IL about -0.8 dB and a fractional bandwidth of 6.1%.

2021-09-29 PIER C Vol. 115, 261-276, 2021. doi:10.2528/PIERC21080508

Ac Low-Frequency Characterization of Stopband Negative Group Delay Circuit

Sofia Fenni, Fayrouz Haddad, Konstantin Gorshkov, Bogdana Tishchuk, Antonio Jaomiary, Fabrice Marty, George Chan, Mathieu Guerin, Wenceslas Rahajandraibe, and Blaise Ravelo

This paper investigates the original circuit theory on stopband (SB) negative group delay (NGD) passive topology. The basic specifications of SB-NGD function are defined by considering the voltage transfer function (VTF) of the passive circuit. An original design method and experimentation tests of SB-NGD circuit are developed. The innovative theoretical analysis is elaborated from both magnitude and GD analytical expression of the VTF model from the resonant LC-series network passive topology. The mathematical existence condition of SB-NGD aspect is analytically explored in function of R, L, and C component parameters. The formulations of the basic equations enabling the calculation of the lumped components of the SB-NGD passive circuit in function of the desired specifications as NGD cut-off frequencies, NGD value and attenuation are established. To confirm the effectiveness of the original SB-NGD circuit theory, a proof-of-concept (POC) of SB-NGD circuit board is designed, simulated, fabricated and experimented. As expected, despite the equivalent series resistor (ESR) effect of the inductor element, the theoretical modelling, simulation and measurement results are in good agreement. The SB-NGD behavior is confirmed with lower and upper cut-off frequencies, 0.7 kHz and 1.35 kHz, respectively. Furthermore, the corresponding NGD minimal values are -33 µs and -11 µs, respectively.

2021-09-28 PIER C Vol. 115, 245-259, 2021. doi:10.2528/PIERC21052404

Novel Sparse Planar Array Synthesis Model for Microwave Power Transmission Systems with High Efficiency and Low Cost

Jianxiong Li and Shengjia Chang

A novel algorithm is developed to realize the optimal synthesis of a sparse nonuniform-amplitude nonuniform-distribution planar array (SNANDPA) in microwave power transmission (MPT) systems. The dual compression factor particle swarm optimization (DCFPSO) algorithm and the subarray partition technique are adopted to realize the optimal synthesis of SNANDPA. The DCFPSO algorithm first optimizes beam collection efficiency (BCE) and side-lobe level outside the receiving region (CSL) of SNANDPA which ensure efficient energy transmission of an MPT system and suppress the influence of electromagnetic wave radiated by antenna array on the environment. The subarray partition technique then simplifies the feed network to minimize the system cost. SNANDPA parameters including transmitting aperture, receiving aperture, BCE, CSL, power pattern, element weight, and element distribution, can be obtained efficiently via the proposed method. Representative numerical cases under the different numbers of subarray and elements conditions are analyzed and compared with those of other two traditional MPT array models. Experimental results show that, when the transmitting aperture is 4.5λ×4.5λ and the square receiving region u0=v0=0.2, BCE and CSL are 94.96% and -17.09 dB, respectively, and only 64 elements and 8 amplifiers are required. We conclude that the proposed model can be used to create an efficient and low-cost MPT system.

2021-09-27 PIER C Vol. 115, 233-244, 2021. doi:10.2528/PIERC21081802

Broadband Asymmetrically Fed Circularly Polarized Slot Antenna for Mid-Band 5G Smartphone Applications

Aniket Vasant Gunjal and Ujwala Kshirsagar

A compact asymmetrically fed U shape slot antenna for 5G smartphone application is presented. The antenna consists of two major components that are responsible for generating broadband circular polarization (CP) (i) the microstrip patch feed structure employed at the top plane and (ii) U shape slot mechanism employed at the ground plane. The U shape ground radiator is approximately half wavelength slot mode which is responsible for lower band CP operation. The planar monopole structure is formed by the microstrip line feed. This planar monopole is a quarter wavelength mode used for achieving higher band CP operation. By combining these two CP modes generated by U shape slot and port-line structure, a broadband CP antenna is designed. The circular polarization is achieved with lesser complexity in the design structure. To get the practical validation of the simulated design, it is then fabricated and tested for measured results without using power divider. The measured axial ratio bandwidth covers from 2.00 GHz to 6.50 GHz (4.50 GHz) and the -10 dB Impedance Bandwidth (IBW) covers from 1.66 GHz to 8.10 GHz (6.44 GHz) respectively. The isolation between two asymmetric port-lines is greater than 14.5 dB within 3-dB axial ratio bandwidth.

2021-09-26 PIER C Vol. 115, 219-232, 2021. doi:10.2528/PIERC21071205

Neural-Network-Based Source Reconstruction for Estimating Linear Synchronous Motor Radiation

Lu Xing, Yinghong Wen, David W. P. Thomas, Jinbao Zhang, and Dan Zhang

An equivalent source model based on neural network is proposed to rapidly estimate the magnetic radiation characteristics of linear synchronous motor (LSM) in electromagnetic suspension (EMS) maglev system. The equivalent source is composed of electric dipoles and a closed three-dimensional (3-D) surface, and is developed in terms of source reconstruction method. A few sampling data of magnetic field simulation results serve as the input information to determine the unknown current distribution on equivalent source model. To solve the inverse radiation problem and characterize the whole radiation pattern with high efficiency, the current distribution signature of equivalent model is fitted into artificial neural network models. Separate neural network models are fitted under different phases of winding excitation, which enables the low-frequency magnetic field estimation under both 3-phase balanced operation and unbalanced operation. The equivalent source model is extended to estimate LSM radiation in multi-source environment, and the comparison with numerical simulation verifies its accuracy and efficiency.

2021-09-25 PIER C Vol. 115, 205-217, 2021. doi:10.2528/PIERC21070804

Behavioral Modeling for Nonlinear Effects of Receiver Front-Ends Based on Block-Oriented Structure

Chongchong Chen, Hongmin Lu, Yu Zhang, and Guangshuo Zhang

In this paper, a novel behavioral model for the receiver front-end is presented. This model allows the accurate prediction of the nonlinear effects of the receiver front-end including the in-band distortion, intermodulation and harmonic generation. The behavioral model is a block-oriented model that consists of three blocks, the frequency conversion block, nonlinear block, and memory linear block. The nonlinear block and memory linear block are represented by the polynomials in time domain respectively, which can characterize the high-order nonlinearities and the strong memory effects by the appropriate adjustment of the polynomial order. An original model parameter identification procedure that can efficiently estimate the model parameters by using the specific input-output data is also proposed. Moreover, the presented behavioral model and identification procedure are assessed by the experiment with the excitation of single-tone signals, multitone signals and WCDMA signals, respectively. The comparison between the measurement and model simulation suggests that the behavioral model has good accuracy of the prediction of the nonlinear effects of the receiver front-end.

2021-09-18 PIER C Vol. 115, 187-203, 2021. doi:10.2528/PIERC21073002

Design of Compact CPW-Fed Symmetrical Staircase-Shaped UWB Antenna Using Transmission Line Model

Budhadeb Maity and Sisir Kumar Nayak

A co-planar waveguide-fed symmetrical staircase-shaped ultra-wideband antenna is proposed in this work. This antenna consists of three pairs of rectangular notches, two symmetrical C-shaped slots and two pairs of quarter-circular-ring-slits which are etched on the rectangular radiator and ground plane, respectively. By sequentially inserting three pairs of rectangular notches with proper positions, an excellent impedance bandwidth of 1.55-16.95 GHz (166.51%), i.e., a 10.94:1 ratio bandwidth is obtained. The total volume of the prototype is merely 0.239×0.224×0.004λl3, λl wavelength of the free space at the lowest operating frequency (i.e., 1.55 GHz). As a result, wider impedance bandwidth, fair gain and better impedance matching of the proposed antenna are obtained. It is observed that the simulation results are in good agreement with the measurement results. The transmission line model (TLM) of the proposed antenna is presented, and it shows the antenna behavior based on the effect of each element. It is observed that the characteristics of the TLM model are close to the simulation result using the CST simulator. The prototype is successfully implemented, fabricated, and compared with the experimental results.

2021-09-17 PIER C Vol. 115, 175-185, 2021. doi:10.2528/PIERC21071602

Crosstalk Analysis of E-Plane Ku Band Waveguide Joints

Neelam Sharma and Debendra Kumar Panda

This paper presents crosstalk analysis of E-plane multichannel waveguide joints for high frequency. The multi-cavity modeling technique and method of moment are used to analyze the crosstalk. Waveguide has many practical uses in high powered RF systems. When two channel waveguides are joined, the phenomenon of crosstalk will certainly appear, and the reason behind is poor workmanship. The gap appearing at the flange joint causes power coupling to the neighboring ports. In this paper two channel E-plane waveguide joints for frequency range 15 GHz to 18 GHz have been analyzed. Scattering parameters data obtained from cavity model analysis have been verified and compared with CST microwave studio simulated and measured data.

2021-09-13 PIER C Vol. 115, 161-174, 2021. doi:10.2528/PIERC21062803

Dual Band Circularly Polarized Modified Ψ-Shape Microstrip Antenna

Amit A. Deshmukh and Anuja Arun Odhekar

Single patch designs of a microstrip antenna with a U-slot or a pair of rectangular slots (E-shape) provide a single band circularly polarized response, and hence they are not useful in frequency and polarization agile applications. In this paper, a modified design of a Ψ-shape microstrip antenna is proposed for dual band and dual sense circularly polarized response. Use of unequal length rectangular slots in the modified patch, optimizes the inter-spacing between the modified TM21 and TM22 resonant modes, surface current distributions and impedance levels at them to yield dual band circularly polarized response. An impedance bandwidth of 1992 MHz (37.05%) is obtained which completely covers the axial ratio bandwidth of 11.84 and 5.67%, in the two bands with frequency ratio of 1.3 in between them, thereby satisfying the requirements of frequency agile systems. Over the impedance and axial ratio bandwidth, the antenna exhibits nearly broadside radiation pattern with a gain of around 7 dBi. A design methodology based on the simple parametric formulation is presented, which helps in realizing a similar antenna in the specific frequency band. The proposed antenna can find applications in frequency and polarization agile systems where the signal loss due to the interference and jamming can be reduced.

2021-09-13 PIER C Vol. 115, 145-160, 2021. doi:10.2528/PIERC21051603

Design and Modelling of Ladder-Shape Topology Generating Bandpass NGD Function

Samuel Ngoho, Yves Constant Mombo Boussougou, Syed Samar Yazdani, Yuandan Dong, Nour Mohammad Murad, Sebastien Lallechere, Wenceslas Rahajandraibe, and Blaise Ravelo

This paper introduces a model and design of an innovative bandpass (BP) negative group delay (NGD) distributed circuit. The passive circuit topology under study is constituted by fully distributed elements without lumped components. The NGD passive structure is implemented as a ladder shape topology composed of distributed transmission line (TL) elements. The S-matrix model is established from TL-based equivalent Z-matrix operations of TLs with respect to the ladder geometry. As a proof of concept, a two-cell ladder prototype is designed in microstrip technology, which is simulated, fabricated, and tested. The calculated and simulated measurements are in very good agreement with the validation of BP NGD behaviour. NGD value is better than -3 ns with centre frequency between 3.56 and 3.68 GHz over more than 30 MHz NGD bandwidth being observed. The circuit operates under insertion loss better than 5 dB and reflection loss better than 8 dB. This innovative BP NGD passive circuit can be useful in the RF and microwave engineering area, for example, to reduce the signal propagation delay in the upcoming and 5G telecommunication systems.

2021-09-13 PIER C Vol. 115, 127-144, 2021. doi:10.2528/PIERC21072202

Research on Estimation Method of Information of Multiple Charged Particles Using Electrostatic Sensor Array

Zhirong Zhong, Hongfu Zuo, Jiachen Guo, and Heng Jiang

The electrostatic sensor is a rapidly developing particle monitoring sensor. This paper applies sensor array to inverse the information carried by detected multiple charged particles precisely. It breaks through the constraint that the detailed information of particles cannot be obtained in previous studies. The proposed method can be widely applied to oil line and gas path debris monitoring. The sensing mathematical model and the finite-element model are established. A compressive sensing-based method is proposed to invert the information of charged particles. Through simulation and experimental verification, the method can accurately estimate the centroid of multiple particles, the total charge quantity of the particle cluster, the spatial position of each particle and the charge quantity carried by each particle in the multiple particles with a low error rate when the multiple particles are distributed near the pipe wall of flow channel.

2021-09-10 PIER C Vol. 115, 111-126, 2021. doi:10.2528/PIERC21072001

Design of MIMO/Smart Antenna Arrays Using Different Array Modules for Handheld Device

Panpan Wei and Wen Geyi

In this paper, an eight-element MIMO smart antenna system consisting of two different array modules for handheld device is proposed. The system is composed of two antenna array modules. The first module is a six-element array operating in N78 (3.3-3.8 GHz) band for 5G, which achieves MIMO functions for receiving and beam scanning for transmitting. The second module is a two-element antenna array, which operates in LTE/WWAN/N78 (0.7-0.91 GHz, 1.63-2.61 GHz, 3.3-3.8 GHz) bands. To take full advantage of the existing antenna resources in the mobile device, the six elements in the first module are combined with the two elements in the second module to form an 8-element array in the overlapping N78 band. Good isolations and envelope correlation coefficients are achieved in the receiving mode by loading L-shaped slots for the combined module. The distribution of excitations for the combined array in the transmitting mode is optimized by the method of maximum power transmission efficiency to direct the beam to the desired direction with maximum possible gain, and is realized by an in-house designed beamforming controller. The impacts of the environments on the antenna array performance are investigated.

2021-09-06 PIER C Vol. 115, 95-110, 2021. doi:10.2528/PIERC21062606

Multiple Sources Localization Based on Independent Doublets Array

Jiacai Jiang

In this paper, an iterative algorithm for the location of multiple sources based on independent doublets arrays is proposed. The array brings a unified signal model for both near-field and far-field incoming sources. The signal model refrains the bias of Fresnel approximate due to the close displacement between elements of each doublet. Only exploiting the geometry of each doublet in direction-of-arrival (DOA) estimation, the proposed algorithm can avoid synchronization technology among different local oscillators of doublets, which means that elements among doublets could be independent. The proposed algorithm employs all the data received by the independent doublets arrays and can deal with more than two sources with only two coherent sensors in each doublet. The algorithm provides a simple approach and obtains acceptable results. Simulation results are illustrated to verify the effectiveness of the proposed algorithm.

2021-08-31 PIER C Vol. 115, 81-93, 2021. doi:10.2528/PIERC21061704

Using a 3D Metamaterial to Enhance the Surface Wave Propagation for High Frequency Over -the-Horizon Radars: from Simulation to Outdoor Measurements

Quentin Herbette, Nicolas Bourey, Michel Menelle, Muriel Darces, Stéphane Saillant, Yves Chatelon, and Marc Hélier

This article is about the characterization of a 3D metamaterial structure arranged to reinforce the surface wave radiation of antennas relevant to High Frequency (HF) surface wave radars. The use of a corrugated surface with a negative equivalent permittivity placed in the vicinity of the antenna increases the surface wave component of the radiated field. In order to confirm the anticipated performance of that metamaterial antenna, near-field measurements have been realized. Also, an original near far-field transformation technique, taking the surface wave into account, is applied to derive the radiation pattern of the antenna. Measurements were first achieved at reduced scale in UHF band and at full scale in HF band. At 1.1 GHz, they were operated on a small scale mock-up in a semi-anechoic chamber. An electric field acquisition setup installed in an Unmanned Aerial Vehicle (UAV) is used to characterize this antenna under outdoor conditions. This measuring system was especially designed for this application. The obtained results are discussed and enable us to validate the expected behavior of the antenna.

2021-08-30 PIER C Vol. 115, 65-80, 2021. doi:10.2528/PIERC21072203

T-Shaped Tri-Band Antenna Based on Characteristic Mode Analysis for Satellite Applications

Fateh Lal Lohar, Indra Bhooshan Sharma, Virender Katewa, and Mahendra Mohan Sharma

This article presents a T-Shaped Tri-Band (TSTB) antenna based on the Characteristic Mode Analysis (CMA) for satellite applications. Tri-band characteristics are achieved by exciting two orthogonal radiating modes for the L5-band and L1-bands, and one higher order radiating mode for the S-band. Initially, cavity model theory is applied to a rectangular antenna to calculate orthogonal modes (TMz010 & TMz001) at L5-band and S-bands, and these modes are validated using the CMA method. With the help of surface current study and modification of a rectangular antenna, the one higher order radiating mode and orthogonal modes are excited by using the CMA method. All desirable radiating modes are excited by a single coaxial feed line in full-wave simulation, which is based on FIT (Finite Integration Technique). The proposed antenna's measured operating frequencies are 1575 MHz (L1-band) for GPS (Global Positioning System) system, 1174 MHz (L5-band), and 2495 MHz (S-band) for IRNSS (Indian Regional Navigation Satellite System) applications, and corresponding impedance bandwidths at S11 ≤ -10 dB are 24 MHz (1563-1587 MHz), 24 MHz (1164-1188 MHz), and 51 MHz (2484-2535 MHz), respectively. The proposed antenna layout is printed on low-cost FR4 material and exhibits good agreement between simulated and measured results using CST and HFSS EM-tool. The proposed antenna is single feed, low profile, and economical with stable broadside radiation patterns along with good gain.

2021-08-24 PIER C Vol. 115, 51-64, 2021. doi:10.2528/PIERC21042402

Performance Optimization of Dual-Feed UWB Annular Ring Antenna with Circular DGS and EBG for SAR Reduction

Mahesh Munde, Anil Nandgaonkar, and Shankar B. Deosarkar

The article presents the design of an Ultra-Wideband (UWB) annular ring antenna which operates over 1.5 GHz to 12 GHz and covers most of the bands of mobile communication (GSM 1800, 1900 and 2100, UMTS, Bluetooth (2.4 GHz), WLAN 2.4/3.5/5 GHz and WiMAX 2.5/3.5/5.5 GHz). The antenna size is 40 x 36.67 x 1.6 mm3, and an FR-4 substrate of permittivity 4.3 with loss tangent of 0.025 is used for fabrication. Circular defect in ground plane of annular ring is used to achieve UWB characteristics. A wideband mushroom type Electromagnetic Band Gap (EBG) unit cell is designed which resonates at 2.3 GHz, and 8-unit cells are placed close to feeds of annular ring patch where current density is more for 2.4 GHz so as to reduce surface waves and ultimately to lower Specific Absorption Rate (SAR). SAR is evaluated with dual-feeds for single element and is lowered up to 83.64% for 1-gram of tissue mass.

2021-08-19 PIER C Vol. 115, 41-50, 2021. doi:10.2528/PIERC21070503

A 28 GHz Surface-Mount Endfire Antenna Based on Ball Grid Array Packaging for 5G New Radio

Xiubo Liu, Wei Zhang, Dongning Hao, and Yanyan Liu

In this article, a 28 GHz endfire antenna based on ball grid array (BGA) packaging is proposed for the 5G mmWave new radio (NR). The antenna is composed of a pair of dipole patches fed by a substrate integrated waveguide (SIW). Besides, quasi-coaxial vertical transition and transition from grounded coplanar waveguide (GCPW) to SIW are designed on the substrate to achieve compact size. The substrate is based on a single-layer printed circuit board (PCB), which can meet the cost-effectiveness requirements of the 5G application. Meanwhile, the proposed antenna can be easily integrated with other surface-mount devices by using the BGA packaging. In particular, it can be mounted near the RF front-end chipset to improve system performance. Finally, the prototype is manufactured and verified. Experimental results show that the -10 dB bandwidth of the proposed antenna is 5.35% in the range of 27.3 to 28.8 GHz, and the peak gain achieves 4.4 dBi at 29 GHz.

2021-08-18 PIER C Vol. 115, 27-40, 2021. doi:10.2528/PIERC21061303

A Novel Multilayer EBG Structure to Reconfigure the Band-Notch of UWB Monopole Printed Antenna

Kompella S. L. Parvathi and Sudha R. Gupta

In high speed indoor communication, ultra-wideband (UWB) plays a crucial role. UWB contains several other narrow band systems, which give interference. In order to reject these narrow bands present in UWB system, a novel multilayer step via electromagnetic band gap (MS-EBG) structure to vary the band-notch of UWB monopole printed antenna is presented in this work. The proposed EBG consists of grooved substrate with step via arrangement. These grooved substrate allow for the deposition of the liquids with different dielectric constants to achieve the variations in band gap center frequency of EBG. The microstrip line based model with equivalent circuit diagram of MS-EBG is developed with experimental results using suspended micro strip line (SML) method, with different liquids like kerosene, sea water, mineral oil, without grooved substrate, etc. The simulated and experimental results show liquid sensing ability of the proposed MS-EBG structure. The application of MS-EBG to vary the band notch in UWB hexagonal monopole antenna (HMA) is also demonstrated. Simulated and experimental results show noticeable variation in the band notch center frequency with different liquids deposited in the grooved substrate. The proposed method required only liquid change arrangement to get desired band notch in UWB monopole antenna. Compared to electrical and mechanical method to get band notch in UWB monopole antenna, the proposed method works without any power supply, active devices and additional complex arrangement.

2021-08-16 PIER C Vol. 115, 17-26, 2021. doi:10.2528/PIERC21070805

Compact Asymmetric Coplanar Strip Fed MIMO Antenna with Band Dispension Characteristics for UWB Applications

Bharghava Punna and Pachiyaannan Muthusamy

A MIMO antenna with ACS- asymmetric coplanar strip feeding technique with compact size for UWB applications of band-notched features is presented. The proposed MIMO antenna contains two orthogonally placed rectangular-shaped radiating elements. The orthogonal mechanism of placement of radiating elements provides a good amount of isolation from 3.09 GHz to 11.13 GHz. The size of the antenna is 27 × 27 mm2. The isolation is more than 17 dB for most of the UWB range. The proposed MIMO antenna represents nearly omnidirectional radiation pattern and low value of envelope correlation coefficient. Because of the usage of ACS feeding techniques, the antenna size is reduced, and it is a uniplanar structure. The diversity performance of the MIMO antenna is explained in terms of ECC-Envelope Correlation Coefficient, DG-Diversity Gain, and TARC-Total Active Reflection coefficient.

2021-08-13 PIER C Vol. 115, 1-15, 2021. doi:10.2528/PIERC21070504

Hexagonal Split Ring Resonator Enclosed Circular Split Ring Resonator Inspired Dual-Band Antenna for Sub-6 GHz 5G NR and IEEE 802.11ba/Be Applications

Pitchai Rajalakshmi and Nagarajan Gunavathi

In this article, a novel Hexagonal Split-Ring Resonator enclosed Circular Split-Ring Resonator (HSRR-CSRR) inspired printed antenna is presented for sub-6 GHz 5G NR and IEEE 802.11ba/be applications. The proposed antenna comprises an HSRR-CSRR and a D-SHSRR metamaterial unit cell with a partial ground plane. The designed antenna is printed on a low-cost FR-4 substrate with dielectric constant εr of 4.4, thickness of 1.6 mm, and loss tangent of 0.02. An HSRR-CSRR metamaterial structure is designed to get the three distinct resonance frequencies at 3.5 GHz, 5.05 GHz, and 6.2 GHz, respectively. To cover the entire band of Sub-6 GHz 5G NR (5-6 GHz), a Double-slit Single Hexagonal Split Ring Resonator (D-SHSRR) is designed for 5.8 GHz and loaded along with the HSRR-CSRR. The operating principle, equivalent circuit, and parametric extraction of the HSRR-CSRR structure are examined. Compared to the conventional antenna, the proposed antenna has a compact size of (0.38λg×0.52λg×0.03λg). The antenna parameters have been investigated using Ansys HFSS 15.0 software. The measured and simulated results are in good agreement.