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Livya Lawrance

Other affiliations: College of Engineering, Guindy
Bio: Livya Lawrance is an academic researcher from Anna University. The author has contributed to research in topics: Phase shift module & Antenna measurement. The author has an hindex of 4, co-authored 6 publications receiving 79 citations. Previous affiliations of Livya Lawrance include College of Engineering, Guindy.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a grid array antenna (GAA) for automotive UWB radar sensors is proposed, which consists of 33 radiating elements and is excited using a common transmission line center fed by a coaxial probe.
Abstract: This communication presents the design of grid array antenna (GAA) for automotive UWB radar sensors. The proposed GAA is constructed using astroid unit cells, which concurrently achieve high gain and bandwidth. The GAA consists of 33 radiating elements and are excited using a common transmission line center fed by a ${50}\text{-}\Omega $ coaxial probe. Furthermore, amplitude-tapering techniques are employed to lower the sidelobe level (SLL). The prototype antenna is fabricated and experimental results are presented. The developed amplitude-tapered GAA provides 2.5 GHz effective operational bandwidth with ${\text{VSWR}} \leq {2}$ and gain variation less than 3 dB. The measured peak gain is 13.87 dB at 24 GHz.

46 citations

Journal ArticleDOI
TL;DR: In this article, a modified antipodal Vivaldi antenna (AVA) with low cross-polarisation is proposed for ultra-wideband communications, where the bandwidth offered by conventional single petal AVA is enhanced by adding another petal.
Abstract: In this study, a modified antipodal Vivaldi antenna (AVA) with low cross-polarisation is proposed for ultra-wideband communications. The bandwidth offered by conventional single petal AVA is enhanced by adding another petal. This dual petal antenna occupies a small volume of 60 × 60 × 0.8 mm 3 and provides operating bandwidth from 2.4 GHz to frequencies >14 GHz. The proposed antenna configuration provides low cross-polarisation level which is 5 dB and an average group delay variation of 0.5 ns. The prototype antenna is fabricated and tested to validate the simulation results.

28 citations

Journal ArticleDOI
TL;DR: In this article, an ultra wideband (UWB) frequency-selective surface (FSS) exhibiting band rejection characteristic is presented, which consists of a single-layer substrate and provides 20 dB attenuation level for a wide bandwidth of 7.53 GHz at the normal incidence.
Abstract: An ultra-wideband (UWB) frequency-selective surface (FSS) exhibiting band rejection characteristic is presented in this paper. The proposed unit cell has the size of 14 × 14 mm2 which is approximately 0.18 × 0.18 λo, where λo corresponds to free space wavelength at the lower cut-off frequency. The proposed UWB FSS consists of a single-layer substrate and provides 20 dB attenuation level for a wide bandwidth of 7.53 GHz at the normal incidence. The proposed FSS is polarization independent and also provides angular-independent operation for the EM wave incidences of 15°, 30° and 45° with 11.5 dB attenuation over a wide range from 4 to 14 GHz.

22 citations

Journal ArticleDOI
TL;DR: In this paper, a compact, unilateral grounded Coplanar Strip (CS) antenna for automotive communications is presented, which is designed for quad band operation covering DCS1800, IEEE 802.11b/g/n standards, Wi-MAX, V2V, and V2I communications.
Abstract: A compact, unilateral grounded Coplanar Strip (CS) antenna for automotive communications is presented in this letter. The antenna is designed for quad band operation covering DCS1800, IEEE 802.11b/g/n standards, Wi-MAX, Vehicle-to-Vehicle (V2V), and Vehicle-to-Infrastructure (V2I) Communications. A simple folded microstrip line radiator along with unilateral ground plane of CS is attempted to generate the required frequency bands. To achieve polarization and pattern diversity functionality, a 4 port diversity antenna array is developed. The antenna unit cells are spaced $0.125{\lambda _{{\rm g}1}}$ calculated at the lowest resonant frequency and are oriented orthogonal to adjacent unit cells to achieve high isolation greater than 20 dB, correlation coefficient less than 0.25 and diversity gain greater than 9.5 dB. The proposed antenna is suitable for automotive communications as it can be conveniently placed anywhere inside the vehicle more specifically in the wind screen, side mirrors and fenders.

11 citations

Journal ArticleDOI
TL;DR: In this paper, a dual-frequency, passive, analog, and reciprocal phase shifter is proposed, deploying the phase-delay characteristics of complementary split-ring resonator (CSRR).
Abstract: Phase shifters are indispensable microwave components. In this paper, a dual-frequency, passive, analog, and reciprocal phase shifter is proposed, deploying the phase-delay characteristics of complementary split-ring resonator (CSRR). A transmission line is loaded with a pair of CSRR in the ground plane and the phase variations are compared with an ideal transmission line. The proposed phase shifter operates in the industrial, scientific and medical (ISM) and wireless local area network (WLAN) bands, providing a phase of 180° at 2.4 GHz and 90° at 5.4 GHz for beam steering applications.

2 citations


Cited by
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Journal ArticleDOI
TL;DR: A new, portable, and low-cost microwave imaging (MWI) system using an iterative enhancing technique for breast imaging that has been able to perform the detection of tumorous cells in breast phantom that can pave the way to saving lives.
Abstract: Globally, breast cancer is a major reason for female mortality. Due to the limitations of current clinical imaging, the researchers are encouraged to explore alternative and complementary tools to available techniques to detect the breast tumor in an earlier stage. This article outlines a new, portable, and low-cost microwave imaging (MWI) system using an iterative enhancing technique for breast imaging. A compact side slotted tapered slot antenna is designed for microwave imaging. The radiating fins of tapered slot antenna are modified by etching nine rectangular side slots. The irregular slots on the radiating fins enhance the electrical length as well as produce strong directive radiation due to the suppression of induced surface currents that radiate vertically at the outer edges of the radiating arms with end-fire direction. It has remarkable effects on efficiency and gain. With the addition of slots, the side-lobe levels are reduced, the gain of the main-lobe is increased and corrects the squint effects simultaneously, thus improving the characteristics of the radiation. For experimental validation, a heterogeneous breast phantom was developed that contains dielectric properties identical to real breast tissues with the inclusion of tumors. An alternative PC controlled and microcontroller-based mechanical MWI system is designed and developed to collect the antenna scattering signal. The radiated backscattered signals from the targeted area of the human body are analyzed to reveal the changes in dielectric properties in tissues. The dielectric constants of tumorous cells are higher than that of normal tissues due to their higher water content. The remarkable deviation of the scattered field is processed by using newly proposed Iteratively Corrected Delay and Sum (IC-DAS) algorithm and the reconstruction of the image of the phantom interior is done. The developed UWB (Ultra-Wideband) antenna based MWI has been able to perform the detection of tumorous cells in breast phantom that can pave the way to saving lives.

111 citations

Journal ArticleDOI
Jun Xu1, Wei Hong1, Hui Zhang1, Guolong Wang1, Yingrui Yu1, Zhi Hao Jiang1 
TL;DR: A novel array antenna with a flat-shoulder shaped radiation pattern is proposed as the transmitting antenna for 77 GHz automotive radar application and a good agreement between the measured data and the synthesized as well as the simulation results are shown, thereby validating the design.
Abstract: A novel array antenna with a flat-shoulder shaped radiation pattern is proposed as the transmitting antenna for 77 GHz automotive radar application. When it is used in an automotive radar comprising one transmitter and multiple identical receivers, it can meet the demands of both long-range and medium-range detections without switching the operation mode back and forth between the long-range radar scenario and the medium-range radar scenario. The proposed antenna concept is fully introduced to explain its mechanism. An unconventional array was synthesized to achieve the desired flat-shoulder shaped radiation pattern. Prototype of the proposed array antenna was also designed according to the array synthesis result, which consists of several linear series-fed patch arrays and a substrate-integrated waveguide power and phase distributing network. Fabrication and measurement of the prototype array antenna were completed, showing a good agreement between the measured data and the synthesized as well as the simulation results, thereby validating the design.

79 citations

Journal ArticleDOI
TL;DR: In this article, two 24 GHz horizontally polarized $1 \times 8$ patch antenna arrays were developed for automotive radar applications, which offer the advantages of wide fan beams and high gain.
Abstract: In this paper, two 24 GHz horizontally polarized $1 \times 8$ patch antenna arrays were developed for automotive radar applications. The proposed antenna arrays offer the advantages of wide fan beams and high gain. The far-field radiation patterns are widened in the E-plane by disturbing the near-field distribution of each driven patch. In Design I, the driven patch is loaded with a parasitic loop, which functions as a director in the E-plane. Due to the directing effect, the E-plane beamwidth can be increased. The experimental verification prepared for Design I showed that a beamwidth of 130° and a gain of 12.2 dBi can be achieved through this method. To further enhance the beamwidth, another array with each patch loaded with parasitic mushroom-like elements was proposed by Design II. The PMLEs are 180° out of phase to their corresponding driven patch. The cancelation effects can be properly managed to slightly sacrifice the gain of the array in return for a wider beamwidth in the E-plane. Design II exhibits a wider beamwidth of 150° and a lower gain of 11.1 dBi.

71 citations

Journal ArticleDOI
TL;DR: This letter presents an eight-port, multiple-polarization, ultrawideband (UWB) diversity antenna array, which consists of eight uncorrelated antennas, of which four are horizontally oriented and the remaining four are vertically oriented to achieve polarization diversity.
Abstract: This letter presents an eight-port, multiple-polarization, ultrawideband (UWB) diversity antenna array. The unit-cell antenna is constructed from a basic square monopole antenna. With suitable modifications in the radiating plane and the ground plane, the unit-cell antenna is designed to operate between 2.9–12 GHz to cover the entire UWB range. The designed UWB radiator is then replicated within a small space to generate triple polarization. The proposed diversity antenna array consists of eight uncorrelated antennas, of which four are horizontally oriented and the remaining four are vertically oriented to achieve polarization diversity. Diversity performance metrics such as envelope correlation coefficient, apparent diversity gain, and effective diversity gain are evaluated and presented. The prototype diversity antenna is fabricated, and experimental results are presented.

51 citations

Journal ArticleDOI
TL;DR: The design, fabrication, and testing of an integrated polarization diversity antenna array for maximizing the wireless channel link in vehicular networks and performance metrics such as envelope correlation coefficient, diversity gain, and mean effective gain under isotropic, indoor, and outdoor conditions are evaluated and presented.
Abstract: The design, fabrication, and testing of an integrated polarization diversity antenna array for maximizing the wireless channel link in vehicular networks are presented in this paper. The diversity antenna is constructed using unit cell radiators that provide two operating modes. The mode transition is achieved using a pair of PIN diodes. In one state, the antenna provides multiband operation centered at 2.4, 3.5, and 5.8 GHz. In the other state, the antenna covers the entire ultra-wideband (UWB) spectrum. The unit cell radiators are distributed in the horizontal and vertical plane to achieve polarization diversity. Apart from offering a polarization diversity antenna, the orientation of antennas offers a reliable link with the communication devices. The prototype antenna array is fabricated and tested for diversity performance. The performance metrics such as envelope correlation coefficient, diversity gain, and mean effective gain under isotropic, indoor, and outdoor conditions are evaluated and presented.

50 citations