Browsing by Author "Rano, Dinesh"

Now showing 1 - 20 of 31

Analysis of Normally Incident EM Waves Reflected from a Conformal Meta-surface
(IEEE, 2022) Rano, Dinesh
This paper reports the conceptualization, and analysis of a geometrical approach to determine the shift in the in-phase reflection of three conformal meta-surfaces (MS). For the proposed approach, a planar array consisting of MS unit cells (MS-UCs) of a given dimension is drawn on a circle of desired radius (r). The path traveled by the reflected and incident EM wave in terms of an electrical length results in the shift of reflection angle. For the validation purpose, the conformed arrays are simulated under x- and y-polarized EM waves. The sum of the incident and reflected phases resulting in total shift is determined theoretically and compared with the simulated shifts of the three arrays. Furthermore, one of the conformed arrays is experimentally evaluated under the TEM incidence and compared with the theoretical and simulated result. The excellent agreement between the theoretical and measured results demonstrates the effectiveness of the proposed work.
Comparative analysis of performance improvement of MPA by using EBG and DGS structures
(IEEE, 2016) Rano, Dinesh
This paper present different design methods to improve the performance of MPA. A comparative analysis of EBG and DGS structures in terms of performance has been given. The proposed DGS structure improves gain, efficiency and the return loss of the antenna. The antenna w/o EBG and DGS resonates at 2.4 GHz offering bandwidth of 67.8 MHz. Three different types of DGS structure have been designed and their effects on the antenna performance have been tabulated. The DGS structure provides good matching with reduction in size more than 4%
Computer Simulation of Modulated Frequency-Selective Surfaces on Mushroom-Shaped Metamaterials
(IEEE, 2021) Rano, Dinesh
This paper presents the results of computer simulation of modulated metasurfaces with mushroom-shaped unit cells. The metasurfaces were designed as a wide wall of a waveguide and as a part of microstrip transmission line. The combination of two types of unit cells that are identical in shape but different in size provides a synergy that allows creating frequency-selective devices with several stop-bands. The proposed devices were simulated using CST Studio Suite and Ansoft HFSS.
Cost-Effective Approach for the Determination of Specific Absorption Rate of Liquid Phantom
(IEEE, 2021) Rano, Dinesh
In this paper, point thermal specific absorption rate (SAR) of the liquid phantoms are determined by simulation and measurement on an elliptical cylinder for a microstrip patch antenna (MPA) operating in the medical body area network (MBAN) band. For this, we measured the temperature rise of the liquids exposed to EM wave (MPA) for a given time. The liquid phantom (homogeneous) is developed by varying the percentage of salt and sugar in 250g of water, whereas, skin phantom is developed by varying the weight of water in 200g of glycerin. The reported technique to measure SAR can provide measurements without the need for an expensive arrangement of dielectric probe kit and this demonstrates the cost-effectiveness of the proposed technique. Finally, we validated our proposed theory with simulation by keeping the conditions identical to measurement which demonstrates excellent resemblance.
Design and analysis of microstrip antenna array in E & H plane for high gain applications
(IEEE, 2015-07) Rano, Dinesh
Linear patch arrays can be very useful where space is the matter of concern in one direction. Like planar array, linear arrays are also capable of providing high gain and directivity with beam scanning. The paper focuses on air borne applications. Proposed linear array are suitable due to its conformability and meeting the constraint of space for such applications. The design presented in this paper proposes to increase the gain and as well as bandwidth by keeping acceptable values of VSWR and return loss.
Design and analysis of wearable patch antenna array for MBAN applications
(IEEE, 2016) Rano, Dinesh
Design idea of wearable rectangular patch antenna and its array for MBAN (2.36 - 2.4 GHz) applications are proposed in this paper. Microstrip line with quarter wave transformer is used for feeding purpose. Polyamide lossy (Nylon-6) is used as dielectric substrate whereas the conductive parts i.e. patch and ground plane consists of nickel - copper - nickel coating on the textile substrate. The presence of highly conductive coating on substrate (i.e., surface resistance of 0.1 ohms/m 2 ) aids in the reduction of losses. Five layer model consisting of bottom textile, air gap, skin, fat and bone is considered here. Since the wearable antennas are body worn devices effect of body curvature is also considered by conforming the antennas on cylindrical surface.
Design of a new uc-planar EBG cell and its application in performance enhancement of microstrip patch antenna/antenna array
(IEEE, 2016) Rano, Dinesh
This paper reports design of a new uc-planar EBG unit cell. Subsequently, this proposed EBG cell has been used to enhance the performance of microstrip patch antenna and its array operating in ISM band (2.4-2.4835 GHz). The effectiveness of the proposed uc-planar EBG unit cell has been demonstrated by comparing the performance with the conventional mushroom type EBG incorporated in the patch and array. The simulated and measured results obtained from the developed prototypes show good agreements but the obtained results are better for the proposed uc-planar EBG cell in terms of gain and efficiency.
Determination of Effective Dielectric Constant and Resonant Frequency of Microstrip Patch Antenna with Multilayered Superstrate Structures
(IEEE, 2019) Rano, Dinesh
A generic iterative empirical model to compute the effective permittivity (ε eff ) and resonant frequency (f r ) of microstrip patch antenna (MPA) covered with multi-layered superstrates is reported. For an MPA covered with multi-layers of superstrate the presented technique makes use of conformal mapping (CM) of dielectric boundaries and series-parallel combination of capacitances between the metallic patch and ground plane to determine ε eff . The developed model can accurately predict ε eff and f r of multi-layered superstrate structure with permittivity greater than 4.5 which is higher than the previous state-of-the-art (i.e. ε r >2.32). It can predict f r of an MPA with relative %error of 1.6% and 0.1% for superstrate having permitivities of 3.66 and 4.7 respectively for considerably thicker superstrates. The presented theory is validated by developing prototypes and a good agreement between the measured and the simulated results confirm this premise. In essence, the technique presented is first of its type to anticipate f r of an MPA covered with superstrate layers of relatively higher permitivities with very small relative %error than the previous works. An algorithm to integrate the developed model with any standard microwave simulator is also proposed. Finally, the proposed theory is applicable for wearable sensors with antenna in it and covered with dielectric superstrate for protection from the environment.
Differential Method for Determining the Specific Absorption Rate of Electromagnetic Energy of a Liquid Phantom
(Springer, 2023) Rano, Dinesh
The wide use of small-sized wearable electronic devices in various practical human activities makes it relevant to measure the proportion of electromagnetic energy absorbed by the human body. One of the most important parameters that determines it is the specific absorption rate. In this article the authors propose a method for determining this coefficient for a liquid phantom with the use of computer simulation and experimental measurement of the microstrip patch antenna parameters. The antenna is located on an elliptical cylinder and operates in the wireless medical body area network. The method is based on measuring the rise in temperature of the liquid phantom exposed to electromagnetic waves generated by a microstrip patch antenna over a certain time. Homogeneous liquid phantom was created by changing the percentage of salt and sugar in 250 g of water, the skin phantom — by changing the percentage of water in 200 g of glycerol. The proposed specific absorption rate measurement method eliminates the need to purchase an expensive set of dielectric probes, which demonstrates its cost-effectiveness. The results of experimental measurements are in good agreement with the results of the performed computer simulation
End-fire Yagi Antenna with DGS for WBAN Applications
(IEEE, 2019) Rano, Dinesh
A planar yagi-uda antenna backed by defected ground structure (DGS) and operating at wireless body area network (WBAN) is reported in this work. The strips in the design apart from the primary feed acts as director and partial ground plane at the back behaves as a reflector. The overall arrangement is suitable to exhibit end-fire radiation pattern with gain in the main lobe and efficiency of 6.8 dB and 90% respectively in air. The net dimension of the antenna is 50mm x 50mm x 1.594mm. Furthermore, the performance of the proposed antenna in terms of return loss, radiation pattern and gain is analyzed in close proximity to human body using the five layer model. The effectiveness of the proposed design is demonstrated through close agreement between the measured and simulated return losses of DGS backed antenna in air.
Enhancing the performance of defected ground structure type near-field radiofrequency WPT system by coupled-line impedance matching
(IET, 2020-07) Rano, Dinesh
This study reports, for the first time, the use of coupled-line-based impedance matching in wireless power transfer (WPT) system. The transmitter and receiver of the WPT system are realised by microstrip feed line and symmetric coupled line at the top plane. The ground plane is realised with triangular-shaped defect along with the excitation slot mounted by an external capacitor. The defect in the ground plane and the external capacitor regulate the resonant frequency and also enable miniaturisation of the WPT system. The design is augmented with a systematic analytical approach for impedance matching and a simplified design procedure for the WPT system. A novel equivalent circuit model consisting of parallel LC network and coupled lines is also developed for the evaluation of the proposed WPT system design technique. A prototype of the system operating at 300 MHz developed on Rogers RO4350B substrate achieves a peak efficiency of 80% at a transmission distance of 17 mm. An excellent agreement between the measured and the electromagnetic simulated results is a testament of the robustness of the proposed design technique. Furthermore, evaluation of the commonly used WPT-related figure of merit shows significant enhancement when compared to the existing state of the art.
Extremely compact EBG-backed antenna for smartwatch applications in medical body area network
(IET, 2019-03) Rano, Dinesh
This paper presents design of a compact interdigital electromagnetic band gap unit cell (IDE) for wearable applications in the medical body area network (MBAN) band. The uniqueness of the proposed cell is in its ability to achieve lower resonant frequency in spite of very compact size of 14.3 mm × 14.5 mm. The cell has adjacent fingers connected in such a way that the net inductance contributed by the metallic strips increases and this aids in the reduction of resonant frequency. An equivalent lumped circuit model supports the analysis of the proposed cell. The evaluation of the developed model is assessed by comparing the reflection phase response obtained from the circuit model and full wave analysis. The proposed design, even though slightly asymmetric, possess polarisation stability and this has been validated using the reflection phase parameter for a plane wave polarised along x -and y-axes. Subsequently, a reflector consisting of 2 × 2 IDE-unit cell to be integrated with monopole antenna of overall size 36 mm × 38 mm × 3.12 mm is designed. The design exhibits a very good agreement between the experimental and the simulated results whereby it is able to provide gain and efficiency of 5.3 dB and 85% respectively at the MBAN frequency.
Geometric Method for Determining the Phase Shift in the Reflection of an Electromagnetic Wave from a Conformal Meta-Surface of a Sensing Element
(Springer, 2022-10) Rano, Dinesh
The current stage of studies of high-impedance conformal surfaces on metamaterials (meta-surfaces) and the development of multifunction measurement devices based on them make the problem of determining the parameters and characteristics of meta-surfaces timely. A geometrical method of determining the phase shift has been developed and proposed for in-phase reflection of an electromagnetic wave from the conformal meta-surface of a sensitive element. It is shown that as a result of meta-surface bending, the incident electromagnetic wave passes along an additional path for a defined electrical length, which results in increasing the phase shift of the reflected wave. Using the CST Studio Suite numerical modeling program, the values of the phase shift of incident and reflected waves were obtained for planar and bent meta-surfaces of sensitive elements of various topology with radii of curvature 40, 50, and 60 mm. The obtained results were compared with analytical calculations, and good correspondence was demonstrated. The proposed method can be applied for calculation and modeling measurement transducers that contain sensitive elements on high-impedance conformal meta-surfaces.
A High Q Dual E-Shaped Defected Ground Structure for Wireless Power Transfer Applications
(IEEE, 2018) Rano, Dinesh
Dual E-shape Defected Ground Structure (DGS) resonator coupled back to back for medium range non-radiative Wireless Power Transfer (WPT) is presented in this paper. The proposed design is based around the concept of resonant inductive coupling for power transfer and consists of E-shaped defect etched in the ground plane of the substrate. The design incorporates capacitive loading for miniaturization and is supported by analytical design procedure. An equivalent parallel RLC resonant circuit in conjunction with coupled mode theory (CMT) and S-parameters aids in the understanding of the proposed WPT system. A prototype, on Rogers RO4350B substrate, has been developed to operate at 0.27 GHz frequency and takes a board size of 20×20 mm 2 . A very good agreement between the simulated and measured results demonstrate the effectiveness of the proposed technique. The achieved performance significantly improves the efficiency of the DGS based WPT systems reported so far.
Interdigital Based EBG: Compact and Polarization Stable for MBAN and Wi-Fi
(IET, 2018) Rano, Dinesh
This paper introduces a new method to design interdigital based EBG structure of very compact size at low frequencies such as MBAN and Wi-Fi. The proposed design utilizes interdigital electrodes (IDE) to miniaturize the conventional mushroom EBG cell by increasing the inductance of the unit cell. The technique presented in this paper miniaturizes the EBG cell size by 55% w.r.t standard cell while demonstrating a band gap from 2.32 - 2.85 GHz. Furthermore, equivalent lumped model of the proposed EBG cell has been developed for a y-polarized EM wave that complies with the frequency of interest. The polarization stability of the EBG cell for any x- or y-polarized EM wave has been demonstrated by a unique method utilizing the transmission characteristic in this work. In addition band gap property of the EBG cell has been validated on an array prototype of 8x7 unit cells. Subsequently planar microstrip antenna incorporating the proposed EBG cells enhances the gain, efficiency and reduces side lobe level by 2 dB, 20%, and - 7 dB respectively w.r.t reference antenna. The prototypes shows good results in terms of return loss.
Measurements and Characterization of a Newly Developed Novel Miniature WIPT System
(IEEE, 2021-05) Rano, Dinesh
This article reports, for the first time, the design and experimental evaluation of a compact wireless information and power transfer (WIPT) system operating at radio frequency (RF). The design of WIPT system is facilitated by the development of a novel tri-band defected ground structure (DGS) based bandstop filter (BSF) operating at three different frequencies of 300, 433, and 700 MHz. Then, two similar BSFs are arranged in a back-to-back configuration to achieve near-field resonant inductive coupling for transfer of information and power. The measurement carried out on a prototyped system shows an excellent agreement between the measured and simulation results and provides power transfer efficiencies of 70.1%, 66%, and 65% at 300, 433, and 700 MHz, respectively, at a separation distance of 23 mm. These figures are a significant advancement over the existing state of the art. Furthermore, up-link and down-link of data transfer at 433 and 700 MHz are demonstrated using universal software radio peripheral (USRP), and power transfer is shown by illuminating a light emitting diode (LED) at 300 MHz.
Miniaturized Slot-loaded Mushroom EBG Cell for MBAN and Wi-Fi Bands
(IEEE, 2020) Rano, Dinesh
Systematic design approach for two new types of EBG cells operating in the Medical Body Area Network (MBAN) and ISM bands are reported. The proposed EBG cells make use of the conventional mushroom and slot loaded EBG cells. The proposed techniques utilize tuning of slot dimensions to achieve miniaturization. A reduction of more than 20% is obtained using the presented designs when compared to the mushroom cell. Furthermore, an algorithm that combines the LC lumped circuit model and dispersion diagram of the EBG cells to expedite the design and analysis is developed. To experimentally validate the design feasibility and hence the bandgap property of the proposed cells, an array of 3x5 unit cells is prototyped. The measured results show good agreement with the simulated results at the desired band.
A Miniaturized Three-Stage Dual-Frequency Matching Network
(IEEE, 2017) Rano, Dinesh
In this paper, design of a miniaturized 3-stage impedance matching network capable of providing good match at two Wi-Fi frequencies of 2.4GHz and 5.8GHz is presented. The proposed technique can provide matching between complex loads and real source at the two chosen frequencies. This technique is able to reduce the circuit size by 50% and 35% when compared to the state-of-the-art 3-stage dual-band impedance matching network at the frequencies of 2.4GHz and 5.8GHz respectively. In addition, the technique can inherently provide wideband matching at both the identified frequencies. For the two chosen frequencies, the increase in bandwidth is 23% and 77% respectively. A prototype developed, on FR4 substrate, provides good agreement between the simulated and measured results.
Misalignment Study of Dual-Band SIMO- and MIMO- WPT Systems
(IEEE, 2023) Rano, Dinesh
In this paper, the misalignment study of single input-multi output (SIMO) and a multi input-multi output (MIMO) defected ground structure based dual-band wireless power transfer (DGS-WPT) system is discussed. As a case study, WPT systems operating at 300 MHz / 700 MHz are designed in CST and prototyped. In this case, the best system efficiency is obtained for the separation of h = 18 mm between the transmitter (TX) and receivers (RXs). The misalignment study includes a detailed analysis of shift in the lateral and angular position of RXs with respect to the TX. It was observed that the misalignment has more negative impact on the performance of SIMO than the MIMO type WPT system.
A Modified Inter-digital EBG Reflector for MBAN Applications
(Wiley, 2018-12) Rano, Dinesh
A modified, compact, and via-less interdigital electromagnetic band gap cell intended for wearable application at medical body area network (MBAN), and Wi-Fi bands is reported in this article. The reflection phase of the proposed EBG unit cell is then investigated to design a reflector consisting of 3 × 2 array of EBG cells for an efficient radiation of a planar monopole antenna. The size and shape of the EBG unit cell has been designed in such a way that it achieves 0° reflection phase with minimum dimension of 14.3 and 15.34 mm along x-axis and y-axis, respectively. Subsequently, the surface wave rejection ability of the EBG incorporated ground plane is also studied and presented in this article. A planar monopole antenna incorporating the proposed EBG reflector at MBAN frequency exhibits gain, and efficiency of 6.4 dB, and 95%, respectively, and has net dimension of 34 mm × 55 mm × 4.67 mm along x-axis, y-axis, and z-axis, respectively. Finally, specific absorption rate (SAR) analysis carried out for one layer, homogenous model, and three-layer, heterogeneous model, shows a considerable reduction in SAR values for 0.5 W of power fed to the antenna. The effectiveness of the proposed approach is demonstrated through good agreement between the simulated and the experimental results.