PIER C | PIER Journals

2019-01-07

PIER C

Vol. 89, 233-241, 2019

download: 420

Compact Microstrip Diplexer Based on Dual Closed Loop Stepped Impedance Resonator

Salif Nabouna Dembele , Jingfu Bao , Ting Zhang and Denis Bukuru

A compact microstrip diplexer based on dual closed loop stepped impedance resonator (DCLSIR) is proposed. The proposed microstrip diplexer is composed of the combination of two DCLSIR bandpass filters (BPFs), which are designed for X-band application. For the demonstration, a dual-channel diplexer has been designed and fabricated using microstrip and printed circuit board (PCB) technologies, respectively. The fabricated diplexer operating at 8.3/10 GHz for X-band application has compact size (15.17 mm x 2.69 mm). The measured results are in good agreement with the full-wave simulation results. Good isolation between two channels is achieved.

2019-01-07

PIER C

Vol. 89, 221-231, 2019

doi:10.2528/PIERC18102104

download: 400

A CPW-Fed CSRR and Inverted U Slot Loaded Triple Band Notched UWB Antenna

Ajay Yadav , Mamta Devi Sharma and Rajendra Prasad Yadav

A CPW-fed ultra-wideband (UWB) monopole antenna design which exhibits triple band stop functions is demonstrated. The proposed antenna comprises a Split Ring Resonator (SRR) and inverted U slots on a metallic patch to exhibit triple band-notch functions for WiMAX (3.3-3.6 GHz), C-band (3.8-4.2 GHz) and WLAN (5.1-5.8 GHz) bands. The slot width optimization is examined to tune the band-notch resonance frequency, and their effects are exhibited by surface current distributions. The antenna has compact size of 26*30 mm², and it functions over 3 to 11 GHz with VSWR < 2 except notched bands. The SRR loaded dual band-notched antenna and amended inverted U slot integrated antenna both are fabricated and their VSWR, radiation characteristics measured. The antenna demonstrates excellent agreement between measured and calculated results.

A CPW-FED CSRR AND INVERTED U SLOT LOADED TRIPLE BAND NOTCHED UWB ANTENNA

2019-01-07

PIER C

Vol. 89, 207-219, 2019

doi:10.2528/PIERC18110803

download: 362

5 × 5 Matrix Patch Type Frequency Selective Surface Based Miniaturized Enhanced Gain Broadband Microstrip Antenna for WLAN/WiMAX /ISM Band Applications

Kalyan Mondal , Debasree Chanda Sarkar and Partha Pratim Sarkar

In this work FSS (Frequency Selective Surface) based broadband, compact and improved gain microstrip patch antenna with defected ground structure for WLAN and WiMAX applications are proposed. A comparative study has been done by the proposed antenna. It is designed on a Rogers RT/duroid substrate (dielectric constant 2.2, thickness 1.6 mm, and loss tangent 0.0009). The structure of the rectangular patch is 0.10λ₀×0.18λ₀ at 5.5 GHz, where λ₀ is the free space wavelength. The lateral ground plane dimensions are 0.29λ₀×0.27λ₀×0.03λ₀ mm³. A patch type FSS is loaded under the ground plane with separation 10 mm from the antenna. Broad frequency band is obtained along with three resonant frequencies at 5.25 GHz, 6.7 GHz and 11.05 GHz. The achieved frequency band and peak gain are 6.79 GHz (4.93 GHz-11.72 GHz) and 8.82 dBi, respectively. Maximum size reduction of 86% is achieved. The designed antenna is simulated, fabricated and measured to verify the results. The measured results are in good agreement with simulated data. It may be applied in WLAN, WiMAX 5.5/5.8 GHz wireless communication and X band applications.

5 × 5 MATRIX PATCH TYPE FREQUENCY SELECTIVE SURFACE BASED MINIATURIZED ENHANCED GAIN BROADBAND MICROSTRIP ANTENNA FOR WLAN/WIMAX/ISM BAND APPLICATIONS

2019-01-04

PIER C

Vol. 89, 191-205, 2019

doi:10.2528/PIERC18112103

download: 335

Optimization and Analysis of 24/16/8 Hybrid Excitation Double Stator Bearingless Switched Reluctance Motor

Qianwen Xiang and Liyun Feng

In order to solve the strong coupling problem of a traditional bearingless switched reluctance motor (BSRM), this paper proposes a new type of hybrid excitation double stator BSRM (HEDSBSRM). The new motor can realize self-decoupling between torque and suspension force. In addition, the two degrees of freedom suspension force can also be decoupled. First, the topology of themotoris proposed, and the generation mechanism of suspension force and torque are expounded.Second, the torque winding structure is optimized.Themulti-objective sensitivity optimization design method is used to screen out the key structural parameters that have the greatest influence on the average suspension force, average torque, and core loss. Then, the optimal structural parameters are obtained by the control variable method. Finally, based on the optimized motor, the finite element method(FEM) is used to analyze the electromagnetic characteristics including the suspension force, torque, and coupling of the motor. The simulation results verify the correctness of the proposed design method and analysis of motor performance.

OPTIMIZATION AND ANALYSIS OF 24/16/8 HYBRID EXCITATION DOUBLE STATOR BEARINGLESS SWITCHED RELUCTANCE MOTOR

2019-01-03

PIER C

Vol. 89, 181-190, 2019

doi:10.2528/PIERC18101605

download: 268

Outage Constraint Robust Transmission Design for Secrecy MIMO SWIPT System with Time Switching

Feng Zhou , Rugang Wang , Xiaofang Yang and Jinhong Bian

In this paper, we investigate a robust secrecy transmission design for a multiple-input multiple-output simultaneous wireless information and power transfer system. Specifically, considering time switching at the transmitter, we aim to maximize the outage secrecy rate by jointly designing the information signal, energy signal, and time switching ratio, under the constraints of transmit power and harvested energy. The formulated problem is highly non-convex due to the difference of two log-det functions and probabilistic constraints. To overcome this obstacle, we divide the original problem into three convex subproblems. Then, an alternative optimization method is proposed. Finally, numerical results are presented to verify the performance of the proposed scheme.

OUTAGE CONSTRAINT ROBUST TRANSMISSION DESIGN FOR SECRECY MIMO SWIPT SYSTEM WITH TIME SWITCHING

2019-01-03

PIER C

Vol. 89, 171-180, 2019

doi:10.2528/PIERC18072802

download: 936

Surface Wave Suppression in LHCP Microstrip Patch Antenna Embedded on Textured PIN Subsrtate

Manidipa Roy and Ashok Mittal

Propagation of surface waves in dielectric underneath a microstrip patch antenna poses serious hindrance to the radiation mechanism. Several methods are being tried for suppression of surface wave. Metamaterial substrate is presented here with periodic arrangement of metallic cylindrical pins except the area underneath the radiating microstrip patch. The periodic arrangement of metallic cylindrical pins with negative dielectric constant has considerably high reflection coefficient to drive the extraneous surface wave fields towards the fringing fields of the antenna. The textured pin substrate leads to generation of forbidden band gap for the propagation of TM₀ surface wave modes and thus enhances radiation characteristics. The proposed structure proves to be highly beneficial for improving radiation efficiency and gain. Parametric analysis has also been presented for the gain enhancement by varying pin diameter, spacing between pins, and air gap between dielectric substrates. A uniform gain of 10 dB has been achieved for a Left Hand Circularly Polarized (LHCP) microstrip patch antenna. The axial ratio achieved in the described band is 200 MHz. The antenna has been designed for WLAN applications.

SURFACE WAVE SUPPRESSION IN LHCP MICROSTRIP PATCH ANTENNA EMBEDDED ON TEXTURED PIN SUBSRTATE

2019-01-03

PIER C

Vol. 89, 161-169, 2019

doi:10.2528/PIERC18111902

download: 427

A Compact Dual Band-Notched MIMO Diversity Antenna for UWB Wireless Applications

Yi Zhao , Fu-Shun Zhang , Li-Xin Cao and Deng-Hui Li

In this paper, a compact ultra-wideband (UWB) multiple-input multiple-output (MIMO) spatial diversity antenna with dual band-notches designed on an FR4 substrate (26 × 28 × 0.8 mm³) is proposed and experimentally investigated. The antenna consists of two tapered microstrip feeding lines and two radiating elements. The inverted L-shaped slits are used to introduce notches at WLAN (5.15-5.85 GHz) and IEEE INSAT/Super-Extended C-bands (6.7-7.1 GHz). The isolation more than 15 dB is achieved through the whole working band (2.9-10.8 GHz) by introducing a T-shaped decoupling structure on the ground plane. Furthermore, envelope correlation coefficient (ECC), radiation patterns of the MIMO antenna are also discussed. The simulated and measured results show that the proposed UWB MIMO antenna is a good candidate for UWB diversity applications.

A COMPACT DUAL BAND-NOTCHED MIMO DIVERSITY ANTENNA FOR UWB WIRELESS APPLICATIONS

2019-01-03

PIER C

Vol. 89, 149-159, 2019

doi:10.2528/PIERC18100102

download: 431

Near Infrared Supercontinuum Generation in Silica Based Photonic Crystal Fiber

Feroza Begum and Pg Emeroylariffion Abas

This research explores a silica based highly nonlinear photonic crystal fiber of near infrared window; solid silica core photonic crystal fiber is suitable for propagating light towards the near-infrared wavelength region. Full vector finite difference method is used for numerical simulation, by solving the generalized nonlinear Schrödinger equation with the split-step Fourier method to show that the design exhibits high nonlinear coefficient, near zero ultra-flattened dispersion, low dispersion slope and very low confinement losses. It is demonstrated that it is possible to generate high power wide supercontinuum spectrum using 2.5 ps input pulses at 1.06 μm, 1.30 μm and 1.55 μm center wavelengths. It is observed that supercontinuum spectrum is broadened from 960 nm to 1890 nm by considering center wavelengths of 1.06 μm, 1.31 μm, and 1.55 μm into silica based index guiding highly nonlinear photonic crystal fiber. Furthermore, immensely short fiber length of 1 m at center wavelengths of 1.06 μm, 1.31 μm and 1.55 μm is possible using the proposed highly nonlinear photonic crystal fiber. The generated high power wide supercontinuum spectrum is applicable as a laser light source in near infrared band.

NEAR INFRARED SUPERCONTINUUM GENERATION IN SILICA BASED PHOTONIC CRYSTAL FIBER

2019-01-02

PIER C

Vol. 89, 133-147, 2019

doi:10.2528/PIERC18101401

download: 1277

Elliptical Slot Circular Patch Antenna Array with Dual Band Behaviour for Future 5G Mobile Communication Networks

Muhammad Irfan Khattak , Amir Sohail , Ubaid Khan , Zaka Barki and Gunawan Witjaksono

This paper presents a dual band circular microstrip patch antenna with an elliptical slot for future 5G mobile communication networks. The antenna has resonating frequencies of 28 GHz and 45 GHz, with bandwidths of 1.3 GHz and 1 GHz, respectively. Efficiency of the antenna is 85.6% at 28 GHz and 95.3% at 45 GHz. The return loss at 28 GHz is -40 dB, with maximum gain of 7.6 dB while at 45 GHz return loss is -14 dB with maximum gain of 7.21 dB. The antenna is designed on a Rogers RT5880 (lossy) substrate with dielectric constant of 2.2 and loss tangent (tanδ) of 0.0013. The antenna has compact size of 6×6×0.578 mm³. Array is used to achieve 12 dB gain, required for mobile communication. The proposed array has resonance frequencies of 28 GHz, 34 GHz and 45 GHz with maximum gain of 13.5 dB and radiation efficiency of 98.75%. Centre series fed technique is used for the excitation of array. SAR value of array antenna obtained at 28 GHz is 1.19 W/kg, at 34 GHz is 1.16 W/kg, and at 44.2 GHz is 1.2 W/kg. CST Microwave Studio, a 3D simulating tool, is used for the antenna design and calculation of the antenna parameters along with the SAR analysis.

ELLIPTICAL SLOT CIRCULAR PATCH ANTENNA ARRAY WITH DUAL BAND BEHAVIOUR FOR FUTURE 5G MOBILE COMMUNICATION NETWORKS

2018-12-29

PIER C

Vol. 89, 121-132, 2019

doi:10.2528/PIERC18111514

download: 334

Effective Modeling of Magnetized Graphene by the Wave Concept Iterative Process Method Using Boundary Conditions

Aymen Hlali , Zied Houaneb and Hassen Zairi

Due to static magnetic field, the conductivity of graphene becomes an anisotropic tensor, which complicates most modeling methodologies. A practical approach to the Wave Concept Iterative Process method (WCIP) modeling of magnetized graphene sheets as an anisotropic conductive surface from the microwave to terahertz frequencies is proposed. We first introduce a brief description of modeling magnetized graphene as an infinitesimally thin conductive sheet. Then, we present a novel manner for the implementation of the anisotropic boundary conditions using the wave concept in the WCIP method. This proposed method is benchmarked with numerical examples to demonstrate its applicability and accuracy. The proposed approach is used to compare the anisotropic model, isotropic model, and the metal for a strip waveguide. We show that the anisotropic model gives more efficient results.

EFFECTIVE MODELING OF MAGNETIZED GRAPHENE BY THE WAVE CONCEPT ITERATIVE PROCESS METHOD USING BOUNDARY CONDITIONS

2018-12-27

PIER C

Vol. 89, 111-120, 2019

doi:10.2528/PIERC18112304

download: 287

Bandwidth Enhancement of Wideband Dual-Polarized Antenna with Loaded Open Stubs for Wireless Communication

Zhaoyang Tang and Ying-Zeng Yin

In this paper, a wideband ±45° dual-polarized antenna is proposedfor wireless communication. An annular ring patch with four arc-shaped slots is employed to generate a wide operating impedance bandwidth. By introducing four open stubs to the antenna element, the impedance bandwidth is enhanced. The antenna has a broad impedance bandwidth (VSWR<2) of 51.2% (1.63-2.75 GHz) and a high port-to-port isolation of 27 dB over the entire band of operation. In addition, a 1×4 antenna array is developed for the wireless communication. Experimental results illustrate that the antenna array features wide operational bandwidth, high port isolation and superior radiation performance.

BANDWIDTH ENHANCEMENT OF WIDEBAND DUAL-POLARIZED ANTENNA WITH LOADED OPEN STUBS FOR WIRELESS COMMUNICATION

2018-12-27

PIER C

Vol. 89, 101-110, 2019

doi:10.2528/PIERC18102902

download: 427

Modelling and Evaluation of Electrical Resonance Eddy Current for Submillimeter Defect Detection

Yew Li Hor , Vinod Kumar Sivaraja , Yu Zhong , Viet Phuong Bui and Christopher Lane

Eddy current (EC) inspection is used extensively in non-destructive testing (NDT) to detect surface-breaking defects of engineering components. However, the sensitivity of conventional eddy current inspection has plateaued in recent years. The ability to detect submillimetre defects before it becomes critical would allow engineering components to remain in-service safely for longer. Typically, it is required that higher frequency EC is employed to achieve a suitable sensitivity for detection of such submillimetre defects. However, that would lead to significant electromagnetic noise affecting the sensitivity of the inspection. To overcome this issue, the electrical-resonance based eddy current method has been proposed, where the electrical enhanced resonance signal increases the contrast between signal and noise, thus improving the sensitivity of the defect detection. This work aims to investigate the electrical-resonance system via simulation technology using combination of fast numerical-based simulation and circuit approach. Leveraging on this model, the detection system can be optimized by performing parameters tuning. Investigation of both experiment and simulation develops a precise calibration model for submillimeter defects detection.

MODELLING AND EVALUATION OF ELECTRICAL RESONANCE EDDY CURRENT FOR SUBMILLIMETER DEFECT DETECTION

2018-12-25

PIER C

Vol. 89, 87-99, 2019

doi:10.2528/PIERC18080404

download: 585

Design and Analysis of Ridge Substrate Integrated Waveguide Bandpass Filter with Octagonal Complementary Split Ring Resonator for Suppression of Higher Order Harmonics

Rakesh Kumar and Shiva Nand Singh

In this research paper, a Ridge Substrate Integrated Waveguide (RSIW) multiple band bandpass filter embedded with an octagonal shape Complementary Split Ring Resonator (CSRRs) is proposed. The electrically coupled octagonal shape CSRR is placed interdigitally in RSIW using transverse coupling technique to improve multiple passband bandwidths. The filter exhibits a highly selective multiple electric or magnetic or bianisotropic mode for different frequencies. The analysis for spurious band suppression has been done by direct method. The prototype configuration of quarter wavelength octagonal CSRR resonators introduces band suppression at all odd harmonics. The proposed structure of filter with dimension 1.36λ_g×0.52λ_g excluding feed port is fabricated. Full wave structure simulated results are compared with measurement ones. The measured passband frequencies and their calculated respective central frequency (f₀), fractional bandwidth (FBW) are in close agreement with the simulated result. The spurious higher order harmonics are observed as suppressed. The filter can be utilized to suppress interference from LAN, WLAN, GSM, WiMAX and variable stopband for ISM interference.

DESIGN AND ANALYSIS OF RIDGE SUBSTRATE INTEGRATED WAVEGUIDE BANDPASS FILTER WITH OCTAGONAL COMPLEMENTARY SPLIT RING RESONATOR FOR SUPPRESSION OF HIGHER ORDER HARMONICS

2018-12-21

PIER C

Vol. 89, 75-85, 2019

doi:10.2528/PIERC18082102

download: 378

Pixel Shape Ground Inspired Frequency Reconfigurable Antenna

Ajay Yadav , Minakshi Tewari and Rajendra Prasad Yadav

A microstrip antenna with a pixel ground structure for single and multiband frequency reconfigurable applications is presented. The partial ground structure of the primary antenna is converted into pixel shapes which produce single and multiband frequency reconfigurable characteristics by the means of RF switches. The designed antenna operations are switchable over multiband, single frequency band and UWB spectrum with distinct configuration of RF switches. Three cases of RF switch configurations have been demonstrated with their simulated and measured results to verify the reconfigurable characteristics.

PIXEL SHAPE GROUND INSPIRED FREQUENCY RECONFIGURABLE ANTENNA

2018-12-20

PIER C

Vol. 89, 61-74, 2019

doi:10.2528/PIERC18092504

download: 259

Electroquasistatic Model of Capacitive Hyperthermia Affected by Heat Convection

Chien-Chang Chen and Jean-Fu Kiang

An electroquasistatic (EQS) model of capacitive hyperthermia for treating lung tumors is proposed, based on which the finite element method is applied to compute the electrical potential in a human thorax model. The temperature distribution in the thorax model, which is surrounded by a bolus maintained at a constant temperature, is computed by numerically solving a bioheat equation, which includes metabolic heat generated in the tissues, heat convection mechanism in tissues and bolus, as well as the heat delivered by the microwave field computed with the EQS model and finite element method. Temperature-dependent blood perfusion rates of blood and muscle, respectively, are adopted to account for the physiological reaction of tissues to temperature variation. By simulations, it is observed that adjusting the dielectric properties of adipose tissue via injection, the time evolution of temperature distribution can be controlled to some extent, providing more flexibility to customize a hyperthermia treatment plan for specific patient.

ELECTROQUASISTATIC MODEL OF CAPACITIVE HYPERTHERMIA AFFECTED BY HEAT CONVECTION

2018-12-18

PIER C

Vol. 89, 51-59, 2019

doi:10.2528/PIERC18110105

download: 842

A Broadband Dual-Polarized Arm-Overlapped Dipole Antenna for Base Station Applications

Jianjun Wu , Wei Yu and Jin Chen

A broadband dual-polarized dipole antenna with overlapped dipole arms is proposed in this paper. To obtain a compact radiator size, the arm-overlapped dipole antenna is constituted by splitting and overlapping the edges of a cross loop dipole. Then four open pins are soldered to the dipole to excite a third resonance at high frequency band. Measured results show that the proposed antenna with a small radiator size of 49×49 mm² has an impedance bandwidth of 49.5% (1.7-2.82 GHz) for VSWR<1.5, port isolation >28 dB and half-power beamwidth (HPBW) of 65º±5º. A 4-element antenna array with 8º±2º electrical down tilt is shown to further validate the performance of the antenna.

A BROADBAND DUAL-POLARIZED ARM-OVERLAPPED DIPOLE ANTENNA FOR BASE STATION APPLICATIONS

2018-12-14

PIER C

Vol. 89, 39-50, 2019

doi:10.2528/PIERC18100901

download: 297

Two Port Integrated Reconfigurable Microstrip Patch Antenna

Sonia Sharma , Chandra Charu Tripathi and Rahul Rishi

A two port, integrated reconfigurable versatile antenna is proposed here. The proposed antenna can reconfigure its frequency, bandwidth, polarization state and radiation pattern and hence is versatile in its characteristics. The antenna is integrated in such a way that the space of one antenna can be used to print two antenna structures to increase the antenna versatility into a small package. PIN diodes are placed in a position so that the electrical switching of the PIN diodes makes every part of the antenna multipurpose. The prototype has been fabricated to authenticate the simulated results. The simulated and measured results are in good agreement. The antenna can be used for Cognitive Radio application.

TWO PORT INTEGRATED RECONFIGURABLE MICROSTRIP PATCH ANTENNA

2018-12-13

PIER C

Vol. 89, 27-38, 2019

doi:10.2528/PIERC18092405

download: 295

A Study of Hybrid Wide Slot Antenna with Hybrid Parasitic Element for Wideband Applications

Barun Kumar , Bhupendra Kumar Shukla , Ajay Somkuwar and Deepak Kumar Raghuvanshi

In this communication, a hybrid shaped wide slot antenna with hybrid parasitic element has been investigated which is fabricated on an FR-4 substrate (tanδ =0.02, ε_r=4.3). The mutual coupling (between the slot and tuning stub), tuning of resonating modes and bandwidth of the antenna are adjusted by changing the dimension of parasitic element and tuning stub. The measured fractional bandwidth of the proposed antenna is 146.82% for S₁₁<-10 dB which covers the frequency span from 0.92 to 6 GHz. This antenna exhibits resonances at 1.094, 1.56, 2.073, 2.67 and 4.02 GHz. Surface current distribution has been investigated, and series of equation are deduced for resonating frequencies. Radiation characteristic exhibits an eight-shaped pattern at fundamental mode frequency whereas at frequencies 2.85 and 3.91 GHz a distorted pattern has been observed. For understanding the behavior of the antenna, structural parameters are varied in specific ranges.

A STUDY OF HYBRID WIDE SLOT ANTENNA WITH HYBRID PARASITIC ELEMENT FOR WIDEBAND APPLICATIONS

2018-12-12

PIER C

Vol. 89, 13-26, 2019

doi:10.2528/PIERC18091801

download: 751

Using Parametric Design to Reduce the EMI of Electronics Products - Example of Medical-Grade Touch Panel Computer

Chien-Yi Huang , Ching-Hsiang Chen and Christopher Greene

With technical advancement and development, the amount of electronic equipment is increasing, while the functions of products are enhanced, and the routing density of Printed Circuit Boards (PCBs) becomes larger. In the electronic industry, medical instruments are used to diagnose, treat, mitigate or prevent human diseases, and maintain and promote health. Industrial PCs for medical use and their accessories should be immune to interference from external electromagnetic noise, and should not become interference sources of electromagnetic noise radiation, so they have become issues of interest with respect to ensuring safety of medical equipments in medical operation environments in recent years. This research relates to parametric design using the Taguchi Method in the early stage of product development for medical-grade touch panel computers. In considering the use of Radiated Emission (RE) in Electromagnetic Compatibility (EMC) as a response value, the experiment covers control factors such as PCB and mechanism design related parameters. In addition, peripheral devices used in conjunction with a product are considered as noise factors when the product is in use, while interaction between the control factors is studied. The Taguchi Method is used to select an appropriate inner/outer orthogonal array, and a response diagram and a variance method are used for analysis to provide an optimal set of design parameters, in which the number of routing layers of a riser card is 6; the EMI filter on the isolated card is 600 Ω; the shunt capacity for the clock on main board is 33p; and the isolated card is grounded. Moreover, it is found that an interaction exists between the number of routing layers of the riser card and the EMI filter of the isolated card. From the result of the experiment, with such a set of parameters, the SN (Signal to Noise Ratio) lies in the confidence interval, indicating good reproducibility of the experiment. Such a parametric design effectively improves the electromagnetic interference (EMI) characteristics of a product to meet design specifications required by customers, accelerate the R&D process of electronic products, and pass EMI test regulations required by various countries in order to improve industrial competitiveness.

USING PARAMETRIC DESIGN TO REDUCE THE EMI OF ELECTRONICS PRODUCTS - EXAMPLE OF MEDICAL-GRADE TOUCH PANEL COMPUTER

2018-12-05

PIER C

Vol. 89, 1-11, 2019

doi:10.2528/PIERC18101604

download: 329

Acceleration of Very Large Reflectarray Radiation Pattern Computation Using an Adaptive Resolution Spectral Grid

Daniel Rodríguez Prado , Manuel Arrebola , Marcos R. Pino , Jose Antonio Encinar Garcinuno and Fernando Las-Heras

In this work, a novel use of the Non-Uniform Fast Fourier Transform (NUFFT) in reflectarray antenna analysis is proposed to greatly accelerate the computation of radiation patterns using a nonuniform, reduced and adaptive grid in the spectral domain. The proposed methodology is very useful for very large reflectarrays, which have very narrow beamwidths due to their large directivity, and shaped-beam reflectarrays for satellite applications such as Direct Broadcast Satellite (DBS), which might require a compliance analysis in very small angular regions. In those cases, high resolution in the radiation pattern is required, while a low resolution could be enough elsewhere to account for side lobes. However, current analysis techniques for such reflectarrays present limitations regarding large memory footprints or slow computations. The methodology presented in this work allows to overcome those limitations by performing computations in a non-uniform, reduced and adaptive grid in the transformed UV domain, achieving faster computations using considerably less memory. Numerical examples for current applications of interest are provided to assess the capabilities of the technique. In particular, the use of the NUFFT allows to compute efciently the radiation pattern in any principal plane with improved resolution for multibeam applications. Also, compliance analyses for DBS applications may be improved with the use of a reduced, multiresolution grid and the NUFFT. The proposed technique is thus suitable to greatly accelerate optimization algorithms.