نتایج جستجو برای: antenna theory

تعداد نتایج: 823303  

Journal: :Wireless Personal Communications 2013
Jamshed Aslam Ansari Anurag Mishra Nagendra Prasad Yadav Prabhakar Singh Babau R. Vishvakarma

In the present paper a dual frequency resonance antenna is achieved by introducing Lshaped slot in circular disk patch. It is analysed by using circuit theory concept. The resonance frequency is found to be 5.087 and 8.455 GHz and the 10 dB bandwidth of the proposed antenna for lower and upper resonance frequency is found to be 4.39 and 4.66 % respectively. It is easy to adjust the higher and l...

Journal: :Physical review letters 2007
Lukas Novotny

In antenna theory, antenna parameters are directly related to the wavelength lambda of incident radiation, but this scaling fails at optical frequencies where metals behave as strongly coupled plasmas. In this Letter we show that antenna designs can be transferred to the optical frequency regime by replacing lambda by a linearly scaled effective wavelength lambda(eff)=n(1)+n(2)lambda/lambda(p),...

2013
Teng Jiao Hua Wang Yang Zhang Xiao Yu Huijun Xue Hao Lv Xijing Jing Hua Zhan Jianqi Wang

When the technique of invasive microwave hyperthermia is applied to cancer treating, the distribution of microwave thermal field and the effect of the therapy are determined by the type of microwave radiative antenna. The thermal field of biological tissue produced by microwave radiative antenna is investigated in this paper. The distribution of thermal field and specific absorption rate (SAR) ...

2001
Carlos Salema Carlos Fernandes Alexandre Martins João Costa

The theory of the dielectric cone antenna has been known since the early seventies. On their own, this antenna has a reasonably circular symmetric radiation pattern but exhibits an undesirably high side-lobe level. A properly designed metallic shield, which does not interfere with the field structure of the dielectric cone, may be used to reduce the side-lobe level. Although in principle this a...

Journal: :IEICE Transactions 2005
Keiji Yoshida Yukako Tsutsumi Haruichi Kanaya

In order to reduce the size of a wireless system, we propose a design theory for the broadband impedance matching circuit which connects an electrically small antenna (ESA) to a semiconductor amplifier. We confirmed its validity for the case of connection between a small slot loop antenna with a small radiation resistance of Ra = 0.776Ω and a semiconductor amplifier with high input impedance of...

2012
J. G. Joshi Shyam S. Pattnaik S. Devi

In this paper, a rectangular slotted microstrip patch antenna with partially loaded metamaterial multiple-split ring resonator (MSRR) ground plane is presented. In unloaded condition, the rectangular slotted patch antenna resonates at 9.38 GHz. When the same antenna is loaded with MSRR in the ground plane, it resonates at lower resonant frequencies 4.60 GHz and 7.70 GHz respectively. The mutual...

2000
Jenn-Hwan Tarng Jiunn-Ming Huang T. S. Lee

Recent research interests in the field of wireless personal communications have been moving to the third-generation cellular systems for higher quality and variable speed of transmission for multimedia information. Spatial and temporal signal processing based on an antenna array will become a breakthrough technique for the cellular systems. In order to design and analyze an antenna array, a rad...

2012
Zahéra Mekkioui

Here we have considered non uniform microstrip leaky-wave antenna implemented on a dielectric waveguide by a sinusoidal profile of periodic metallic grating. The non distribution of the attenuation constant α along propagation axis, optimize the radiating characteristics and performances of such antennas. The method developped here is based on an integral method where the formalism of the admit...

2004
Alina Moussessian David B. Rutledge

A new V-shaped slot antenna built on a dielectric substrate is presented. The antenna is a non-resonant, travelling-wave design, with a predicted impedance in the range from 50R t o €400. Calculations indicate that this antenna should have a gain of 15 dB with 3-dB beamwidths of loo in the H plane and 134' in the E plane. Pattern measurements at QOGHz support the theory. It should be possible t...

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