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In the present paper, the cross polarization reduction and improvement in the sidelobes have been discussed for a multiple beam offset parabolic reflector antenna illuminated by an array of uniformly excited tri-mode horns. The simulated secondary patterns have been obtained for a single tri-mode horn fed offset reflector and also for a tri-mode horn array fed multibeam offset reflector. The results...
This paper presents the design and development of two, three and four elements series fed microstrip leaky-wave antenna (MLWA) for dual beam operation for 60deg skewing angle between the beams. The proposed technique consists of slot used between the array elements, which eliminates active phase shifter to achieve beam skewing. If the array elements are increased from two to four in MLWA the power...
Sheet beam is employed in THz devices as the beam offers an effective interaction with the RF signal. Sheet beam gun design is a challenge in achieving required flatness and laminarity over the length of RF-beam interaction. As per the published literature, sheet beam shape is obtained by using complicated shapes of cathode, BFE and anode. In the present work a planar gun geometry has been proposed...
Conformal mapping has been used extensively for the design of planar lines. However, this approach needs to be improved for the design of CPS. Two different approximations have been used in this connection; duality between CPW and CPS, and partial capacitance approach. The validity of these assumptions is investigated in this paper. Conformal mapping method is combined with FEM to determine epsivre...
The paper presents the radiation performance of an elliptical (a=15 mm, b=10.5 mm) patch antenna having circular slot (R=4.8 mm) designed on glass epoxy FR4 substrate and its performance is compared with a simple elliptical patch antenna without slot. The simulation results for this antenna are obtained with available IE3D simulation software by varying semi major axis (a) and semi minor axis (b)...
In the present paper radiation performance of a right triangular microstrip antenna are investigated in two component warm ionized plasma medium comprising of electrons and ions together and expressions of the field intensities for electromagnetic and electroacoustic modes for this antenna mounted on a re-entry vehicle are derived by applying linearized hydrodynamic theory coupled with vector function...
The advantages of microwave assisted synthesis over thermal method are enhanced reaction rates, less or no formation of side products short reaction time, higher yields of pure products and reaction can be carried on a preparative scale in open vessels. Thus we introduce here with an efficient, rapid reaction, with atom economy follows an ecofriendly protocol, a concept of ldquoGreen Chemistryrdquo...
A dual band RFID applications in 800 - 900 MHz and 2400 MHz band is presented. The Asymmetric Coplanar Strip (ACS) fed antenna consists of inverted L shaped monopole with a capacitive loading to provide necessary impedance matching and current distribution. The antenna has wide bandwidth from 790 MHz to 1050 MHz and from 2350 MHz to 2640 MHz coving the RFID UHF and Microwave frequencies. The uniplanar...
This paper presents the simulation results obtained with a circular patch antenna having an off centered narrow ring slit. With a particular location of ring slit near periphery of circular geometry, antenna resonates at two different frequencies which lie in the lower and upper band of Wi-Max communication adopted by IEEE 802.16. The efficiency and gain of antenna at one of these frequencies are...
The fractal geometries such as Koch curve, Sierpinsky gasket, and Hilbert curve, etc. have been widely studied and applied to design several microwave devices, such as antennas, frequency selective surfaces (FSS), and photonic band gap (PBG) devices. There are several advantages of these fractal devices including reduction of resonant frequencies, smaller size and broadband width. In this paper a...
In the present paper, a pentagonal microstrip patch antenna is proposed to achieve compact size, broadband and dual frequency operation. It is observed that the proposed antenna is radiating at two different frequencies without much loss in its radiation performance showing broad band performance. Both these resonance frequencies lie in the median band (3.25 to 3.85 GHz) of WiMax systems, a new standard...
The paper presents a modified rectangular patch microstrip antenna having a triangular notch in one of its straight arm and designed on dielectric material under the presence of variable air gap. The measured performances of this antenna without air gap are compared with those obtained through simulation results of this antenna under the presence of variable air gap. It is observed that the performance...
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