Analysis of radiation characteristics by diffraction theory in the principal E-plane of typical horn antennas

2005 ◽  
Author(s):  
Jiunn Yu ◽  
R. Rudduck
Keyword(s):  
Diffraction Theory ◽  
Radiation Characteristics ◽  
Horn Antennas

Analysis for Radiation Characteristics of Horn Antenna for Out of Band

2011 ◽  
Vol 383-390 ◽  
pp. 2935-2940
Author(s):  
Rong Kong ◽  
Dong Lin Su ◽  
Qiu Yuan Lv
Keyword(s):  
Frequency Band ◽  
Electromagnetic Compatibility ◽  
Beam Width ◽  
Horn Antenna ◽  
Simulation Software ◽  
Radiation Characteristics ◽  
Horn Antennas ◽  
Main Research ◽  
Working Frequency ◽  
Antenna Characteristics

The idea of this paper roots in the electromagnetic compatibility design of the whole aircraft system, in which out of band characteristics of airborne antennas are of equal importance as their characteristics in band. The definition of antenna characteristics for out of band is interpreted. Horn antennas are the main research objects in this paper. In order to make characteristic of this type antenna for out of band have a general, this paper is special to select pyramidal horn antenna and conical horn antenna. The characterization framework of horn antennas radiation characteristics for out of band is established, and the theoretical expressions of their radiation characteristics for out of band are given. In ensuring better antenna characteristics in band, four horn antennas that are different types of sizes, different frequency band width are simulated and analyzed by using electromagnetic simulation software HFSS. It is meaningful to analyze radiation characteristics and summarize different features for various performance parameters of these horn antennas for in band and out of band. Focus on characteristics of the changes for the maximum gain, 3dB beam width parameters of horn antennas within the working frequency band and out of working band. The results show that: radiation characteristics of horn antenna are the law within the working frequency band and out of working band.

Radiation characteristics of strip loaded hollow dielectric E-plane sectoral horn antennas

1997 ◽  
Vol 33 (24) ◽  
pp. 2002 ◽  
Author(s):  
V.P. Joseph ◽  
S. Mathew ◽  
J. Jacob ◽  
U. Raveendranath ◽  
K.T. Mathew
Keyword(s):  
Radiation Characteristics ◽  
Horn Antennas ◽  
Sectoral Horn

Radiation characteristics of dielectric-loaded horn antennas

1970 ◽  
Vol 6 (1) ◽  
pp. 20-21 ◽  
Author(s):  
M.A.K. Hamid ◽  
R.J. Boulanger ◽  
N.J. Mostowy ◽  
A. Mohsen
Keyword(s):  
Radiation Characteristics ◽  
Horn Antennas

Relative Intensities in ED Patterns From Thin Gold Films

1972 ◽  
Vol 30 ◽  
pp. 636-637
Author(s):  
R. H. Morriss ◽  
J. D. C. Peng ◽  
C. D. Melvin
Keyword(s):  
Theoretical Calculations ◽  
Diffraction Theory ◽  
Gold Films ◽  
Reasonable Accuracy ◽  
Experimental Conditions ◽  
Crystal Perfection ◽  
Heavy Atoms ◽  
Fine Focus ◽  
Convergent Beam ◽  
Beam Diffraction

Although dynamical diffraction theory was modified for electrons by Bethe in 1928, relatively few calculations have been carried out because of computational difficulties. Even fewer attempts have been made to correlate experimental data with theoretical calculations. The experimental conditions are indeed stringent - not only is a knowledge of crystal perfection, morphology, and orientation necessary, but other factors such as specimen contamination are important and must be carefully controlled. The experimental method of fine-focus convergent-beam electron diffraction has been successfully applied by Goodman and Lehmpfuhl to single crystals of MgO containing light atoms and more recently by Lynch to single crystalline (111) gold films which contain heavy atoms. In both experiments intensity distributions were calculated using the multislice method of n-beam diffraction theory. In order to obtain reasonable accuracy Lynch found it necessary to include 139 beams in the calculations for gold with all but 43 corresponding to beams out of the [111] zone.

“Preparation of Single Crystalline Gold Films for ED Studies”

1972 ◽  
Vol 30 ◽  
pp. 634-635
Author(s):  
Joseph D. C. Peng
Keyword(s):  
Crystal Morphology ◽  
Diffraction Theory ◽  
Scattering Matrix ◽  
Vacuum Evaporation ◽  
Gold Films ◽  
Matrix Formulation ◽  
Silver Films ◽  
Single Crystalline ◽  
Grating Pattern ◽  
Stacking Disorder

The relative intensities of the ED spots in a cross-grating pattern can be calculated using N-beam electron diffraction theory. The scattering matrix formulation of N-beam ED theory has been previously applied to imperfect microcrystals of gold containing stacking disorder (coherent twinning) in the (111) crystal plane. In the present experiment an effort has been made to grow single-crystalline, defect-free (111) gold films of a uniform and accurately know thickness using vacuum evaporation techniques. These represent stringent conditions to be met experimentally; however, if a meaningful comparison is to be made between theory and experiment, these factors must be carefully controlled. It is well-known that crystal morphology, perfection, and orientation each have pronounced effects on relative intensities in single crystals.The double evaporation method first suggested by Pashley was employed with some modifications. Oriented silver films of a thickness of about 1500Å were first grown by vacuum evaporation on freshly cleaved mica, with the substrate temperature at 285° C during evaporation with the deposition rate at 500-800Å/sec.

The Interpretation of Crystal Lattice Images

1972 ◽  
Vol 30 ◽  
pp. 550-551
Author(s):  
J. M. Cowley ◽  
Sumio Iijima
Keyword(s):  
Crystal Orientation ◽  
Diffraction Theory ◽  
Phase Changes ◽  
Electron Wave ◽  
Crystal Lattices ◽  
Heavy Atoms ◽  
Lattice Images ◽  
The Right ◽  
Intuitive Interpretation ◽  
Suitable Approximation

The imaging of detailed structures of crystal lattices with 3 to 4Å resolution, given the correct conditions of microscope defocus and crystal orientation and thickness, has been used by Iijima (this conference) for the study of new types of crystal structures and the defects in known structures associated with fluctuations of stoichiometry. The image intensities may be computed using n-beam dynamical diffraction theory involving several hundred beams (Fejes, this conference). However it is still important to have a suitable approximation to provide an immediate rough estimate of contrast and an evaluation of the intuitive interpretation in terms of an amplitude object.For crystals 100 to 150Å thick containing moderately heavy atoms the phase changes of the electron wave vary by about 10 radians suggesting that the “optimum defocus” theory of amplitude contrast for thin phase objects due to Scherzer and others can not apply, although it does predict the right defocus for optimum imaging.

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