Papers by Shailendra Shastri
CRC Press eBooks, Oct 26, 2022
Malaysian Journal of Science, 2021
A compact broadband BALUN transformer is designed using the Klopfenstein taper line transformer a... more A compact broadband BALUN transformer is designed using the Klopfenstein taper line transformer approach to transform a 50 Ω impedance into 100 Ω. To reduce the length of the conventional BALUN, a straight microstrip (MS) line is modified as a curved MS line. The proposed compact BALUN is 56.7%-73% smaller w.r.t the straight conventional BALUN but at the cost of a 4.5%-13% reduction in the overall band. The conventional BALUN has a measured % bandwidth of 165, while the compact BALUN has a result of 159. The measured results agree with the simulated results.
Engineering, Technology & Applied Science Research, 2018
Antenna design becomes very difficult at very small wavelengths and a special lab is required to ... more Antenna design becomes very difficult at very small wavelengths and a special lab is required to manufacture a small antenna which costs a lot. A new approach is proposed to enhance the bandwidth of the loop antenna which can be designed at very high frequency using conventional PCB design. The proposed antenna is a nonuniform loop and covers UWB frequency range. The nonuniform structure of the loop is designed using the concept of both thin and thick loop antenna together which leads to an improvement in the antenna bandwidth. The proposed nonuniform loop antenna covers a band of 91.4% which is higher than any existing printed loop antenna. The frequency ranges from 3.54GHz to 9.5GHz and the measured result is in agreement with the simulated result. This technique can be very helpful in designing UWB antennas in the range of Ku or higher than this.
Engineering, Technology & Applied Science Research, 2018
In this paper, a loop antenna loaded with coplanar strip (CPS) line is proposed as a multiband an... more In this paper, a loop antenna loaded with coplanar strip (CPS) line is proposed as a multiband antenna. The CPS line is added with two switches to vary the antenna perimeter to cover seven different bands. The CPS line introduced into the loop is not only useful in reconfiguring antenna dimensions but also provides stationary radiation patterns for the all the covered bands. The proposed antenna works in single and dual-band modes. When the proposed antenna works as a single band antenna, it produces a band from 4.2GHz to 5.7GHz. Under dual-band operation, it produces bands from 3.75GHz to 4.7GHz and from 6.4GHz to 7.8GHz. The other dual-band mode ranges from 3.5GHz to 3.8GHz and from 5.58GHz to 7.4 GHz. The simulated and measured results are in good agreement and the proposed antenna can be used satisfactorily for W-LAN and WiMax applications. The proposed technique can also be used for size reduction of loop antennas.
HELIX, 2018
In this paper, a printed loop antenna with current reconfiguration technique is proposed to impro... more In this paper, a printed loop antenna with current reconfiguration technique is proposed to improve the usability of the loop as a multiband antenna for UWB applications ranging from 3.1 GHz to 10.6 GHz. The current reconfiguration is achieved using a capacitive gap along the circumference of the loop antenna. The shift in the location of the capacitive gap changes the current distribution in the antenna and new bands are generated. It is found that using a single capacitive gap along the loop, the antenna can be operated as a wide band antenna whose frequency ranges from 6 GHz to 10.8 GHz with % bandwidth of 57. The proposed loop can also be used as dual and triple band antenna in the frequency range from 6 GHz to 10.8 GHz by simply switching ON and OFF the switches. The proposed antenna generates the highest numbers of bands at the minimum expense of switches. The proposed loop without capacitive gap is capable of covering only 24% out of the 3.1 GHz-10.6 GHz range. The range of band can be varied from 24% to 57% using the switches. The proposed antenna very well rejects the WLAN and WiMAX bands.
2008 International Conference on Recent Advances in Microwave Theory and Applications, 2008
This paper presents a modified loop capable of generating circular polarized wave at UHF, L and S... more This paper presents a modified loop capable of generating circular polarized wave at UHF, L and S bands. Modified loop comprise of loop and folded dipole antenna. The folded dipole was selected to ensure close loop as well as the introduction of N no. of folded dipoles for future research. Two modified loops for 3 and 5 radii were developed
2012 Nirma University International Conference on Engineering (NUiCONE), 2012
A circle can be considered as a n-sided polygon where n tends to infinity. The basic motive of th... more A circle can be considered as a n-sided polygon where n tends to infinity. The basic motive of this comparative study is to study the relation between the two loop structures circular and hexagonal large loop antennas, and provide comparative statistical data for future research on hexagonal large loop antenna. Circular large loop antenna of 6 cm radius and Hexagonal large loop antenna of 6 cm side are selected. Both the antennas were simulated in the UHF band and the basic antenna parameters like physical construction, bandwidth, gain, return loss and radiation pattern are compared. These results were also verified to an extent practically using a ZVH antenna analyzer. It is observed that the hexagonal antenna is more efficient than the circular antenna for a certain range of frequencies. The hexagonal loop antenna also has greater selectivity for its resonant frequency.
2016 International Conference on Advances in Computing, Communications and Informatics (ICACCI), 2016
Development in field of broadband access technologies is on the rise due to increase in demand of... more Development in field of broadband access technologies is on the rise due to increase in demand of high speed data services for portable devices. Despite recent advances in broadband wireless technologies, there remain a number of critical issues to be resolved. One of the major concerns is the implementation of compact antennas that can operate in a wide frequency band. Another important problem affecting the antenna performance is selecting a proper wideband feed network. The balun provides not only balanced fields but also impedance matching to the antenna. Different kinds of balun have been developed over the past decades. From 1994, several CPW (Coplanar Waveguide) to CPS (Coplanar Strip lines) baluns have been reported. However, these baluns are band limited. To overcome these issues, two designs are proposed in this paper using CPW to CPS wideband balun. First design is using symmetric CPW to CPS balun which uses bond wires and radial slots to do away with the discontinuities between CPW and CPS and we obtain a bandwidth of 2.7 GHz between 1 to 3.7 GHz. Second design is using asymmetric CPW to CPS which does away with the discontinuities without using radial slot and bond wires and we obtain a bandwidth of 5.8 GHz from 2.2 to 8 GHz.
2016 International Conference on Signal Processing, Communication, Power and Embedded System (SCOPES), 2016
A novel printed loop antenna is designed introducing a C-shape portion to the left arm of the cir... more A novel printed loop antenna is designed introducing a C-shape portion to the left arm of the circular loop antenna. The proposed antenna gives frequency range from 3.5 to 6.20GHz. It is observed that lower frequency band depends on the C-shaped structure of circular loop antenna. However, the upper frequency band depends on the coupled tapered transmission line. Balun transformer of Z=50Ω to 80Ω is merged with the proposed antenna to enhance the bandwidth having frequency range of 2.7 to 7.1 GHz. Antenna is designed on FR4 substrate and can be used for various application such as ISM band, WLAN band and UWB application.
Helix, Jun 30, 2018
A printed loop antenna is designed to produce three distinct bands to cover six different frequen... more A printed loop antenna is designed to produce three distinct bands to cover six different frequency bands from UWB groups. Loop is fed using a printed BALUN transformer. The first band is available from 3.09 GHz to 4.44 GHz, the second band is available from 6.11 GHz to 7 GHz and the third band is available from 8.85 GHz to 10.5 GHz. The measured results are in good agreement with the simulated results. Frequency band from 3.0 GHz to 4.44 GHz covers UWB BAND-1 and BAND-2, the frequency band from 6.11 GHz to 7 GHz covers UWB BAND-7 and the last band from 8.85 GHz to 10.5 GHz covers UWB BAND-12, BAND-13, and BAND-14. Antenna rejects IEEE 802.11 Wi-Fi / WLAN band at 5.8 GHz.
Engineering, Technology & Applied Science Research
Antenna design becomes very difficult at very small wavelengths and a special lab is required to ... more Antenna design becomes very difficult at very small wavelengths and a special lab is required to manufacture a small antenna which costs a lot. A new approach is proposed to enhance the bandwidth of the loop antenna which can be designed at very high frequency using conventional PCB design. The proposed antenna is a nonuniform loop and covers UWB frequency range. The nonuniform structure of the loop is designed using the concept of both thin and thick loop antenna together which leads to an improvement in the antenna bandwidth. The proposed nonuniform loop antenna covers a band of 91.4% which is higher than any existing printed loop antenna. The frequency ranges from 3.54GHz to 9.5GHz and the measured result is in agreement with the simulated result. This technique can be very helpful in designing UWB antennas in the range of Ku or higher than this.
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Papers by Shailendra Shastri