Rekha G.Nair - Academia.edu (original) (raw)
Papers by Rekha G.Nair
Scientific Reports, May 4, 2023
This article presents the combined analysis of reconfigurable power division and Negative Group D... more This article presents the combined analysis of reconfigurable power division and Negative Group Delay (NGD) in a power divider. A novel composite transmission line (CT) based reconfigurable power divider with high power division ratio, variable negative group delay and lower characteristic impedance is presented in this work. The impedance transformation in composite transmission lines controls both NGD and power division. This power divider possesses a wide range of power division ratios from 1 to 39, adequate isolation, impedance matching, and NGD of-3.4 ns to-4.7 ns in the reconfigurable transmission path. The NGD is achieved without using any additional group delay circuits. Theoretical equations corresponding to the low characteristic impedance of the transmission line sections and that of isolation elements are derived. The measurement results justifies the attainment of high tuning of the power division ratio, and NGD. Isolation and return loss are higher than-15dB at the cen...
Advanced Electromagnetics
In this paper, a design approach for getting dual-band working in a Wilkinson-based power divider... more In this paper, a design approach for getting dual-band working in a Wilkinson-based power divider (WPD) without adding any reactive elements or open- or short-circuited stubs is presented. The transfer matrix approach is used to get the analytical solutions of the required design equations. Admittance representation with respect to the input and output ports is done to perform even-odd mode analysis. In this impedance of each section is kept constant but the electrical length varies. Different combinations of electrical lengths are taken such that the overall length remains constant. The electrical lengths are selected based on dual-band analysis and depend on the tuning ratio. The conditions for attaining the impedance matching are applied to the obtained design equations and hence found out the values of the matching resistors to be placed between the transmission line sections. The proposed power divider centered at 2.5GHz and 7GHz is theoretically calculated simulated and fabric...
2021 Third International Conference on Intelligent Communication Technologies and Virtual Mobile Networks (ICICV)
A multiple band resonator power divider hinge on the technique of multiple mode resonance has bee... more A multiple band resonator power divider hinge on the technique of multiple mode resonance has been proposed and designed relying on the method of equivalent replacement of single quarter-wave transmission line with suitable coupling. Each fraction of the quarter-wave line is coupled with the other using two types of coupling networks, one is L section RC network, and the other is I section resistor network. Both structures provide resonance in three different frequency modes. Among these, two of them are responsible for broadening the operating band. This may be controlled precisely by the center frequency ratio of the power divider. The number of resonating modes achievable is limited by the practically available values of resistors and capacitors. This design has advantages like a single layer, compact structure, wide frequency ratio, and high isolation.
2021 IEEE Indian Conference on Antennas and Propagation (InCAP), 2021
A reconfigurable power divider with a com-pact structure is presented in this work. A varactor ca... more A reconfigurable power divider with a com-pact structure is presented in this work. A varactor cas-caded by a transmission line at the input port and a shunt-connected varactor placed across the output ports acts as reconfigurable units. The divider provides good isolation and matching in the entire reconfigured operating band. To justify the adopted design topology a reconfigurable power divider with 2.4 GHz center frequency is designed and simulated. The obtained results indicates that the power divider has a wide tuning range along with better return loss and isolation in the entire tuning range,
2018 International Conference on Circuits and Systems in Digital Enterprise Technology (ICCSDET), 2018
Data transfer rate of communication systems have been extremely increased due to increase in numb... more Data transfer rate of communication systems have been extremely increased due to increase in number of users. UWB antenna system is designed to improve the data transfer rate in communication system, in which more than one antenna is used. In this context, UWB multiple input multiple output (MIMO) has been designed. Here, two symmetrical G shape antenna elements are designed for ultra wide band applications operating in the frequency range from 2.2 GHz to 13.3 GHz. There will be interference and coupling effects in MIMO antenna due to signal leakage from one antenna to another. Hence isolation has to be provided to reduce the interference and coupling loss. An isolation structure will be designed such that, it gives better isolation in upper UWB frequencies. Different isolation structures are provided in the ground plane in order to find better isolation between antenna elements. Based on antenna characteristics, the performance of antenna system is to be studied. An isolation struc...
2016 International Conference on Emerging Technological Trends (ICETT), 2016
The researches and literature on directional modulation are mainly centered on direction dependen... more The researches and literature on directional modulation are mainly centered on direction dependent, simultaneous multichannel data transmission and the design and structural aspects of the antenna and peripherals involved. Also the literature throws light only to researches done within the realm of pre-known receiver locations. This work is mainly intended to study the aspects regarding mobile receivers when directional or direct antenna modulation (DM/DAM) techniques are employed. This paper looks forward to the implementation of adaptive directional/direct antenna modulation (ADAM).
IJIREEICE, 2016
Main objective of wireless communication system is the design of wideband, multiband low profile ... more Main objective of wireless communication system is the design of wideband, multiband low profile small antenna. A fractal antenna effectively utilizes the available space within a sphere of radius "r" which improves the bandwidth of the antenna enclosed in the sphere [2]. The term fractal refers to miniaturized structure which stands for irregular or broken pieces. Several natural phenomenons like trees, mountains etc. shows fractal nature. The fractal concepts are used in antenna theory and design and there are many studies and implementation of fractal antenna elements and arrays. This paper brings a comparison of different shrinking methods on antenna size based on fractal geometry while maintaining performance parameters. This paper presents a survey on fractal antennas designed with different geometric structures, its iteration process, radiation parameters etc. Which are used for wireless applications.
Scientific Reports, May 4, 2023
This article presents the combined analysis of reconfigurable power division and Negative Group D... more This article presents the combined analysis of reconfigurable power division and Negative Group Delay (NGD) in a power divider. A novel composite transmission line (CT) based reconfigurable power divider with high power division ratio, variable negative group delay and lower characteristic impedance is presented in this work. The impedance transformation in composite transmission lines controls both NGD and power division. This power divider possesses a wide range of power division ratios from 1 to 39, adequate isolation, impedance matching, and NGD of-3.4 ns to-4.7 ns in the reconfigurable transmission path. The NGD is achieved without using any additional group delay circuits. Theoretical equations corresponding to the low characteristic impedance of the transmission line sections and that of isolation elements are derived. The measurement results justifies the attainment of high tuning of the power division ratio, and NGD. Isolation and return loss are higher than-15dB at the cen...
Advanced Electromagnetics
In this paper, a design approach for getting dual-band working in a Wilkinson-based power divider... more In this paper, a design approach for getting dual-band working in a Wilkinson-based power divider (WPD) without adding any reactive elements or open- or short-circuited stubs is presented. The transfer matrix approach is used to get the analytical solutions of the required design equations. Admittance representation with respect to the input and output ports is done to perform even-odd mode analysis. In this impedance of each section is kept constant but the electrical length varies. Different combinations of electrical lengths are taken such that the overall length remains constant. The electrical lengths are selected based on dual-band analysis and depend on the tuning ratio. The conditions for attaining the impedance matching are applied to the obtained design equations and hence found out the values of the matching resistors to be placed between the transmission line sections. The proposed power divider centered at 2.5GHz and 7GHz is theoretically calculated simulated and fabric...
2021 Third International Conference on Intelligent Communication Technologies and Virtual Mobile Networks (ICICV)
A multiple band resonator power divider hinge on the technique of multiple mode resonance has bee... more A multiple band resonator power divider hinge on the technique of multiple mode resonance has been proposed and designed relying on the method of equivalent replacement of single quarter-wave transmission line with suitable coupling. Each fraction of the quarter-wave line is coupled with the other using two types of coupling networks, one is L section RC network, and the other is I section resistor network. Both structures provide resonance in three different frequency modes. Among these, two of them are responsible for broadening the operating band. This may be controlled precisely by the center frequency ratio of the power divider. The number of resonating modes achievable is limited by the practically available values of resistors and capacitors. This design has advantages like a single layer, compact structure, wide frequency ratio, and high isolation.
2021 IEEE Indian Conference on Antennas and Propagation (InCAP), 2021
A reconfigurable power divider with a com-pact structure is presented in this work. A varactor ca... more A reconfigurable power divider with a com-pact structure is presented in this work. A varactor cas-caded by a transmission line at the input port and a shunt-connected varactor placed across the output ports acts as reconfigurable units. The divider provides good isolation and matching in the entire reconfigured operating band. To justify the adopted design topology a reconfigurable power divider with 2.4 GHz center frequency is designed and simulated. The obtained results indicates that the power divider has a wide tuning range along with better return loss and isolation in the entire tuning range,
2018 International Conference on Circuits and Systems in Digital Enterprise Technology (ICCSDET), 2018
Data transfer rate of communication systems have been extremely increased due to increase in numb... more Data transfer rate of communication systems have been extremely increased due to increase in number of users. UWB antenna system is designed to improve the data transfer rate in communication system, in which more than one antenna is used. In this context, UWB multiple input multiple output (MIMO) has been designed. Here, two symmetrical G shape antenna elements are designed for ultra wide band applications operating in the frequency range from 2.2 GHz to 13.3 GHz. There will be interference and coupling effects in MIMO antenna due to signal leakage from one antenna to another. Hence isolation has to be provided to reduce the interference and coupling loss. An isolation structure will be designed such that, it gives better isolation in upper UWB frequencies. Different isolation structures are provided in the ground plane in order to find better isolation between antenna elements. Based on antenna characteristics, the performance of antenna system is to be studied. An isolation struc...
2016 International Conference on Emerging Technological Trends (ICETT), 2016
The researches and literature on directional modulation are mainly centered on direction dependen... more The researches and literature on directional modulation are mainly centered on direction dependent, simultaneous multichannel data transmission and the design and structural aspects of the antenna and peripherals involved. Also the literature throws light only to researches done within the realm of pre-known receiver locations. This work is mainly intended to study the aspects regarding mobile receivers when directional or direct antenna modulation (DM/DAM) techniques are employed. This paper looks forward to the implementation of adaptive directional/direct antenna modulation (ADAM).
IJIREEICE, 2016
Main objective of wireless communication system is the design of wideband, multiband low profile ... more Main objective of wireless communication system is the design of wideband, multiband low profile small antenna. A fractal antenna effectively utilizes the available space within a sphere of radius "r" which improves the bandwidth of the antenna enclosed in the sphere [2]. The term fractal refers to miniaturized structure which stands for irregular or broken pieces. Several natural phenomenons like trees, mountains etc. shows fractal nature. The fractal concepts are used in antenna theory and design and there are many studies and implementation of fractal antenna elements and arrays. This paper brings a comparison of different shrinking methods on antenna size based on fractal geometry while maintaining performance parameters. This paper presents a survey on fractal antennas designed with different geometric structures, its iteration process, radiation parameters etc. Which are used for wireless applications.