Now showing items 1-20 of 91
Next Page| Abstract: | An asymmetric coplanar strip (ACS) fed dual band F-shaped antenna covering the 2.4/5.2 GHz WLAN bands is presented. The optimized dimensions of the proposed uniplanar antenna are 21 mm × 19 mm when printed on a substrate of dielectric constant 4.4 and height 1.6 mm. The dual band nature of the antenna is brought about by the various current paths in the F-shaped structure and the ground plane. The antenna exhibits nearly omnidirectional radiation characteristics and moderate gain in both the operating bands. Details of the antenna design, simulation, and experimental results are presented and discussed. |
| URI: | http://dyuthi.cusat.ac.in/purl/2718 |
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| Dyuthi-P00356.pdf | (416.5Kb) |
| Abstract: | Active microwave imaging is explored as an imaging modality for early detection of breast cancer. When exposed to microwaves, breast tumor exhibits electrical properties that are significantly different from that of healthy breast tissues. The two approaches of active microwave imaging — confocal microwave technique with measured reflected signals and microwave tomographic imaging with measured scattered signals are addressed here. Normal and malignant breast tissue samples of same person are subjected to study within 30 minutes of mastectomy. Corn syrup is used as coupling medium, as its dielectric parameters show good match with that of the normal breast tissue samples. As bandwidth of the transmitter is an important aspect in the time domain confocal microwave imaging approach, wideband bowtie antenna having 2:1 VSWR bandwidth of 46% is designed for the transmission and reception of microwave signals. Same antenna is used for microwave tomographic imaging too at the frequency of 3000 MHz. Experimentally obtained time domain results are substantiated by finite difference time domain (FDTD) analysis. 2-D tomographic images are reconstructed with the collected scattered data using distorted Born iterative method. Variations of dielectric permittivity in breast samples are distinguishable from the obtained permittivity profiles. |
| URI: | http://dyuthi.cusat.ac.in/purl/2735 |
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| Dyuthi-P00369.pdf | (1.249Mb) |
| Abstract: | A dual-port dual-polarized compact microstrip antenna for avoiding cross coupling between the two frequency bands is proposed and analyzed. This antenna offers channel isolation better than 25 dB, and is more compact compared to a conventional rectangular patch. Analytical equations for calculating the resonant frequencies at both ports are also presented. The theoretical calculations are verified using experimental results |
| URI: | http://dyuthi.cusat.ac.in/purl/1393 |
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| Analysis and de ... act microstrip antenna.PDF | (1.268Mb) |
| Abstract: | A new compact microstrip antenna element is analyzed. The analysis can accurately predict the resonant frequency, input impedance, and radiation patterns. The predicted results are compared with experimental results and excellent agreement is observed . These antenna elements are more suitable in applications where limited antenna real estate is available |
| URI: | http://dyuthi.cusat.ac.in/jspui/handle/dyuthi/1568 |
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| Analysis of a New Compact Microstrip Antenna.PDF | (3.188Mb) |
| Abstract: | A new compact micro strip antenna element is analyzed. The analysis can accurately predict the resonant frequency, input impedance, and radiation patterns. The predicted results are compared with experimental results and excellent agreement is observed . These antenna elements are more suitable in applications where limited antenna real estate is available |
| URI: | http://dyuthi.cusat.ac.in/purl/1362 |
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| Analysis of a New Compact Microstrip Antenna.PDF | (3.188Mb) |
| Abstract: | The closed form expression for the radiated power of a half-wave microstrip patch is modified to calculate the impedance bandwidth of a printed dipole. Analyses of cavity backed flared and end-loaded printed dipoles are presented |
| URI: | http://dyuthi.cusat.ac.in/jspui/handle/dyuthi/1578 |
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| Analysis of cavity backed printed dipoles.PDF | (989.1Kb) |
| Abstract: | Design equations are presented for calculating the resonance frequencies for a compact dual frequency arrow-shaped microstrip antenna. This provides a fast and simple way to predict the resonant frequencies of the antenna. The antenna is also analyzed using the IE3D simulation package. The theoretical predictions are found to be very close to the IE3D results and thus establish the validity of the design formulae |
| URI: | http://dyuthi.cusat.ac.in/purl/1381 |
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| Analytical Equa ... ncy Microstrip Antenna.PDF | (2.229Mb) |
| Abstract: | A modified H-plane sectoral horn antenna with identical E- and'H- plane.patterns over the X-band frequency is discussed. This system has significantly reduced side lobes and hack lobes. Half=power beam width and gain of the antenna are also improved with enhanced matching , Experimental results for a number of horns with various flanges are presented . These find practical application for illuminating symmetric antennas like paraboloids and polarization measurements in radio astronomy, etc. Compared to the fixed pyramidal horns. the present system offers great convenience in trimming the antenna characteristics |
| URI: | http://dyuthi.cusat.ac.in/purl/1433 |
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| Axially symmetr ... -plane sectoral horns.PDF | (1.253Mb) |
| Abstract: | Reduction of radar cross -section of dihedral corner reflectors using simulated corrugated surface (SCS) is reported. The technique is found to be more effective in the reduction of RCS or corner reflectors for normal incidence . A typical reduction of 40-50 dB is achieved using this method. |
| URI: | http://dyuthi.cusat.ac.in/jspui/handle/dyuthi/1575 |
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| Backscattering ... rs using SCS technique.PDF | (1.362Mb) |
| Abstract: | Reduction of radar cross -section of dihedral corner reflectors using simulated corrugated surface (.SCS) is reported. This technique is found lo be more effective in the reduction of RCS or corner reflectors for normal incidence . A typical reduction of 40-50 dB is achieved using this method |
| URI: | http://dyuthi.cusat.ac.in/purl/1365 |
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| Backscattering ... rs using SCS technique.PDF | (1.362Mb) |
| Abstract: | A new dual port microstrip antenna geometry for dual frequency operation is presented. The structure consists of the intersection of two circles of the same radius with their centres displaced by a small fraction of the wavelength . This antenna provides wide impedance bandwidth and excellent isolation between its ports. The gain of the antenna is comparable to that of a standard circular microstrip antenna operating at the same resonant frequency. A theoretical analysis for calculating the resonant frequencies of the two ports is also presented |
| URI: | http://dyuthi.cusat.ac.in/purl/1350 |
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| Broadband dual frequency microstrip antennas.PDF | (838.1Kb) |
| Broadband dual frequency microstrip antennas.PDF | (838.1Kb) |
| Abstract: | A microstrip antenna with large bandwidth is developed using a parasitic technique . Compared to the available wide-baud antennas,the proposed antenna structure is very compact and gives a lessdistorted radiation pattern with frequency . An impedance bandwidth,eight times that of a conventional patch antenna of the same size, Isachieved. The concept of coupled microstrip line model Is extended fortheoretical interpretation of the impedance loci |
| URI: | http://dyuthi.cusat.ac.in/purl/1360 |
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| Broad-Band Gap Coupled Microstrip Antenna.PDF | (2.586Mb) |
| Abstract: | The detection of buried objects using time-domain freespace measurements was carried out in the near field. The location of a hidden object was determined from an analysis of the reflected signal. This method can be extended to detect any number of objects. Measurements were carried out in the X- and Ku-bands using ordinary rectangular pyramidal horn antennas of gain 15 dB. The same antenna was used as the transmitter and recei er. The experimental results were compared with simulated results by applying the two-dimensional finite-difference time-domain(FDTD)method, and agree well with each other. The dispersi e nature of the dielectric medium was considered for the simulation. |
| URI: | http://dyuthi.cusat.ac.in/purl/2983 |
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| Dyuthi-P00419.pdf | (131.7Kb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1583 |
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| Circularly pola ... act microstrip antenna.PDF | (1.230Mb) |
| Abstract: | Design and development of a circularly polarized and matched H-plane sectorial horn antenna have been reported By proper trimming of the flange parameters any desired polarization can be obtained from the horn |
| URI: | http://dyuthi.cusat.ac.in/jspui/handle/dyuthi/1550 |
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| A circularly po ... s design & develpoment.PDF | (822.3Kb) |
| Abstract: | Design of a dual-port circular patch antenna with a sector-slot for dual-frequency operation is presented. The antenna resonates at two distinct frequencies with orthogonal polarizations and broad radiation characteristics. Unlike the conventional circular patch, this antenna can be microstrip-fed to operate at either of the resonances. The two polarizations can be simultaneously excited using two electromagnetically coupled ports with an isolation better than −30 dB between the ports. This antenna has the added advantage of size reduction of 44% compared to the conventional circular patch without any reduction in gain. |
| URI: | http://dyuthi.cusat.ac.in/purl/2728 |
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| Dyuthi-P00365.pdf | (124.9Kb) |
| Abstract: | compact microstrip antenna integrated with an amplifier having an area reduction of 70%, compared to the standard circular microstrip patch antenna, is presented. The antenna also provides an enhanced gain of 10-dB more than its passive counter part. The measured 2:1 VSWR band width is -4% at 790 MHz, which is 2.5 times larger than that of the passive microstrip antenna |
| URI: | http://dyuthi.cusat.ac.in/purl/1402 |
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| Compact amplifi ... ted microstrip antenna.PDF | (933.7Kb) |
Now showing items 1-20 of 91
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