scispace - formally typeset
Search or ask a question
Author

Sangeetha Subbaraj

Bio: Sangeetha Subbaraj is an academic researcher from VIT University. The author has contributed to research in topics: Monopole antenna & Reconfigurable antenna. The author has an hindex of 9, co-authored 23 publications receiving 247 citations. Previous affiliations of Sangeetha Subbaraj include Anna University & College of Engineering, Guindy.

Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a novel patch antenna with frequency and pattern reconfiguration with polarization switching is presented, which consists of a rhombus-shaped radiator with three excitation lines oriented at different angles.
Abstract: This letter presents the design of a novel patch antenna with frequency and pattern reconfiguration with polarization switching. The proposed antenna consists of a rhombus-shaped radiator with three excitation lines oriented at different angles. All the excitation lines are connected to a common feedline. The reconfiguration is achieved by changing the bias states of three pairs of p-i-n diodes. The dynamic nature of the antenna offers two operating bands, viz., 5.2/5.8 GHz, and provides linear/circular/±45° slant polarization. Furthermore, the pattern can be tilted 30° in right- and left-hand directions. The proposed antenna exhibits cross-polarization discrimination greater than 20 dB in all the operating modes. The prototype antenna is fabricated, and the simulation results are verified using measurements.

72 citations

Journal ArticleDOI
TL;DR: In this paper, a novel frequency and pattern-reconfigurable antenna consisting of a simple rectangular patch with two longitudinal slits is presented, and the slits are connected to the patch through a pair of p-i-n diodes.
Abstract: This letter presents the design of a novel frequency- and pattern-reconfigurable antenna. The antenna consists of a simple rectangular patch with two longitudinal slits. The slits are connected to the patch through a pair of p-i-n diodes to enable frequency reconfiguration and pattern reconfiguration. The reconfigurable patch antenna operates at the frequency 4.5 and 4.8 GHz/5.2 and 5.8 GHz and has a pattern tilt of −30°, 0°, +30°. The prototype antenna is fabricated, and its performance is validated using measurements. Measured results agree well with the simulated results.

60 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

Journal ArticleDOI
TL;DR: In this article, the design of a compact loop antenna with independent frequency tuning is presented, which consists of a feed line fed by a $50~\Omega $ coaxial probe and four resonating arms on the adjacent sides of the feed line.
Abstract: This communication presents the design of a compact loop antenna with independent frequency tuning. The proposed antenna consists of a feed line fed by a $50~\Omega $ coaxial probe and four resonating arms on the adjacent sides of the feed line. The two outer resonating arms are directly coupled to the feed line and the other two inner resonating arms are coupled to the outer arms. The proposed antenna has a footprint of 25 mm $\times 10$ mm $\times0.2$ mm. The designed antenna operates at 0.9, 2.4, 3.5, and 5.5 GHz. Each of these bands is individually tuned using varactor diodes. Thus, the aggregation of these tunable bands provides wide bandwidth. The impedance bandwidth and percentage bandwidth of the antenna are 270/1000/400/700 MHz and 33%/47.6%/11%/12.7%, respectively. Furthermore, the gain and efficiency of the antenna are 1.7/1.3/2.1/2 dBi and 60%/63%/65%/69%, respectively. The prototype antenna is fabricated and tested. The measured impedance and radiation characteristics of the antenna are in good correlation with the simulation results.

28 citations


Cited by
More filters
Journal Article
TL;DR: In this paper, the authors presented a reconfigurable antenna capable of independently reconfiguring the operating frequency, radiation pattern and polarization, using a switched grid of small metallic patches known as pixel surface as a parasitic layer to provide reconfiguration capabilities to existing antennas acting as driven element.
Abstract: This communication presents a reconfigurable antenna capable of independently reconfiguring the operating frequency, radiation pattern and polarization A switched grid of small metallic patches, known as pixel surface, is used as a parasitic layer to provide reconfiguration capabilities to existing antennas acting as driven element The parasitic pixel layer presents advantages such as low profile, integrability and cost-effective fabrication A fully operational prototype has been designed, fabricated and its compound reconfiguration capabilities have been characterized The prototype combines a patch antenna and a parasitic pixel surface consisting of 6 $\,\times\,$ 6 pixels, with an overall size of $06 \lambda \times 06 \lambda$ and 60 PIN-diode switches The antenna simultaneously tunes its operation frequency over a 25% frequency range, steers the radiation beam over ${\pm 30^\circ}$ in E and H-planes, and switches between four different polarizations ( ${\mathhat{\rm x}},$ ${\mathhat{\rm y}}$ , LHCP, RHCP) The average antenna gain among the different parameter combinations is 4 dB, reaching 6–7 dB for the most advantageous combinations The distance between the driven and the parasitic layers determines the tradeoff between frequency tuning range (12% to 25%) and radiation efficiency (45% to 55%)

140 citations

Journal ArticleDOI
TL;DR: This work reviews some recently proposed reconfigurable antenna designs suitable for use in wireless communications such as cognitive-ratio (CR), multiple-input multiple-output (MIMO), ultra-wideband (UWB), and 4G/5G mobile terminals.
Abstract: Reconfigurable antennas play important roles in smart and adaptive systems and are the subject of many research studies. They offer several advantages such as multifunctional capabilities, minimized volume requirements, low front-end processing efforts with no need for a filtering element, good isolation, and sufficient out-of-band rejection; these make them well suited for use in wireless applications such as fourth generation (4G) and fifth generation (5G) mobile terminals. With the use of active materials such as microelectromechanical systems (MEMS), varactor or p-i-n (PIN) diodes, an antenna’s characteristics can be changed through altering the current flow on the antenna structure. If an antenna is to be reconfigurable into many different states, it needs to have an adequate number of active elements. However, a large number of high-quality active elements increases cost, and necessitates complex biasing networks and control circuitry. We review some recently proposed reconfigurable antenna designs suitable for use in wireless communications such as cognitive-ratio (CR), multiple-input multiple-output (MIMO), ultra-wideband (UWB), and 4G/5G mobile terminals. Several examples of antennas with different reconfigurability functions are analyzed and their performances are compared. Characteristics and fundamental properties of reconfigurable antennas with single and multiple reconfigurability modes are investigated.

111 citations

Journal ArticleDOI
TL;DR: In this paper, a printed and minimal size antenna having the functionality of frequency shifting as well as pattern reconfigurability is presented, where the antenna consists of three switches and the desired beam from the antenna can be obtained by adjusting the ON and OFF states of Switches 2 and 3.
Abstract: A printed and minimal size antenna having the functionality of frequency shifting as well as pattern reconfigurability is presented in this work. The antenna proposed in this work consists of three switches. Switch 1 is a lumped switch that controls the operating bands of the antenna. Switch 2 and Switch 3 controls the beam switching of the antenna. When the Switch 1 is ON, the proposed antenna operates at 3.1 GHz and 6.8 GHz, covering the 2.5–4.2 GHz and 6.2–7.4 GHz bands, respectively. When Switch 1 is OFF, the antenna operates only at 3.1 GHz covering the 2.5–4.2 GHz band. The desired beam from the antenna can be obtained by adjusting the ON and OFF states of Switches 2 and 3. Unique beams can be obtained by different combination of ON and OFF states of the Switches 2 and 3. A gain greater than 3.7 dBi is obtained for all four cases.

58 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

Journal ArticleDOI
TL;DR: In this article, a high efficiency and accurate measurement of microwave resonator sensor using microstrip planar structural technology is presented, which is designed based on the bridge split ring topology.
Abstract: This letter presents a high efficiency and accurate measurement of microwave resonator sensor using microstrip planar structural technology The structure is designed based on the bridge split ring topology The sensor has the ability to characterize liquid solvents using the extraction of polynomial fitting technique The bridge equivalent circuit configuration allows the electromagnetic wave to focus on the sensing medium in order to gain high electric flux density, thus react as pushing effect for high Q factor The bridge structure amplifies the electric field distribution As demonstrated by the results, the unloaded ${Q}_{u}$ -factor improves more than 400 over the narrow bandwidth at operating frequency of 23 GHz, and provides less than 10-dB insertion loss By comparison, this design has an identical performance goal and provides excellent sensing capability which can be implemented in pharmaceutical, biomedical, and beverage industries application

49 citations