Performance Analysis of Microwave Radio Refractivity on Radio Field Strength and Radio Horizon Distance Over Akure, Nigeria

2014 ◽  
Vol 79 (3) ◽  
pp. 1893-1909 ◽  
Author(s):  
Adekunle Titus Adediji ◽  
Mahamod Ismail ◽  
Jit Singh Mandeep
Keyword(s):  
Performance Analysis ◽  
Field Strength ◽  
Microwave Radio

scholarly journals Performance Analysis of the Impact of Rain Attenuated Signal on Mobile Cellular Terrestrial Links in Jos, Nigeria

2020 ◽  
pp. 14-26
Author(s):  
O. J. Igbekele ◽  
B. J. Kwaha ◽  
E. P. Ogherohwo ◽  
J. T. Zhimwang
Keyword(s):  
Performance Analysis ◽  
Mobile Network ◽  
Mean Value ◽  
Temperate Climate ◽  
Radio Link ◽  
Clear Sky ◽  
Mobile Cellular ◽  
Microwave Radio ◽  
Induced Signal ◽  
The Impact

The 12 to 18 GHz frequency bands are commonly deployed for mobile network metropolitan microwave radio links using small antennas and low transmit power to deliver high channel capacities. Jos Plateau region with the blend of tropical and temperate climate is characterized with high severe rain impairment on terrestrial links operating at frequencies above 10 GHz, for mobile network backhaul system remaining a big challenge in the design of a microwave radio link. Therefore, this study presents the performance analysis of the impact of rain attenuated signal on mobile cellular terrestrial links in Jos under clear sky and rain condition. The cell site locations were divided in two clusters of Jos lowland and Jos highland. Drive test tools, radio local monitor terminal (LMT) and Davis weather station were employed over radio links interconnecting live 2G/3G nodal network, for the measurement of the mean value of one minute rainfall rates and the corresponding rain-induced signal. The results obtained revealed that more budget provision was obtained by the study calculation in over 60% of the study centers. More so, when the study fade margin estimation was put to test, up to 4.27 Mbps download speed was achieved, the speed almost as high as the highest speed, 4.29 Mbps recorded under the clear sky for ITU-R. More so, as low as 0.7% packet loss was recorded against the study link margin budget under same rain condition causing over 62.3% for PLA010 in Jos lowland cluster. Also, instances of slight under-budgeting were observed in highland clusters PLA064 and PLA025 as 35.01 dB and 34.99 dB respectively when tested with the Study calculated values.

scholarly journals Chaotic characteristics of microwave radio field strength over Nigeria

2021 ◽  
Vol 2034 (1) ◽  
pp. 012024
Author(s):  
A T Adediji ◽  
J S Ojo ◽  
O A Abimbola
Keyword(s):  
Field Strength ◽  
Microwave Radio

On the Configuration of the Magnetic Field of β CrB

1976 ◽  
Vol 32 ◽  
pp. 613-622
Author(s):  
I.A. Aslanov ◽  
Yu.S. Rustamov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radial Velocity ◽  
Magnetic Field Strength ◽  
Complex Shape ◽  
Rotation Period ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Secular Variations ◽  
The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

Improvements in the electron probe forming capabilities and x-ray hole counts in the Philips TEM

1983 ◽  
Vol 41 ◽  
pp. 376-377
Author(s):  
Richard L. McConville
Keyword(s):  
Field Strength ◽  
Electron Probe ◽  
Spherical Aberration ◽  
Focal Length ◽  
Objective Lens ◽  
Parallel Beam ◽  
Tilt Axis ◽  
X Ray ◽  
Small Probe ◽  
Specimen Height

A second generation twin lens has been developed. This symmetrical lens with a wider bore, yet superior values of chromatic and spherical aberration for a given focal length, retains both eucentric ± 60° tilt movement and 20°x ray detector take-off angle at 90° to the tilt axis. Adjust able tilt axis height, as well as specimen height, now ensures almost invariant objective lens strengths for both TEM (parallel beam conditions) and STEM or nano probe (focused small probe) modes.These modes are selected through use of an auxiliary lens situ ated above the objective. When this lens is on the specimen is illuminated with a parallel beam of electrons, and when it is off the specimen is illuminated with a focused probe of dimensions governed by the excitation of the condenser 1 lens. Thus TEM/STEM operation is controlled by a lens which is independent of the objective lens field strength.

A photoelectron microscope study of surfaces

1989 ◽  
Vol 47 ◽  
pp. 10-11
Author(s):  
W. Engel ◽  
M. Kordesch ◽  
A. M. Bradshaw ◽  
E. Zeitler
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Field Strength ◽  
Uv Light ◽  
Physical Property ◽  
Photon Flux ◽  
Mercury Lamp ◽  
Object Surface ◽  
The Sixties ◽  
Physical Features

Photoelectron microscopy is as old as electron microscopy itself. Electrons liberated from the object surface by photons are utilized to form an image that is a map of the object's emissivity. This physical property is a function of many parameters, some depending on the physical features of the objects and others on the conditions of the instrument rendering the image.The electron-optical situation is tricky, since the lateral resolution increases with the electric field strength at the object's surface. This, in turn, leads to small distances between the electrodes, restricting the photon flux that should be high for the sake of resolution.The electron-optical development came to fruition in the sixties. Figure 1a shows a typical photoelectron image of a polycrystalline tantalum sample irradiated by the UV light of a high-pressure mercury lamp.

Performance Evaluation of a Novel Type of Low-Energy Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 354-355
Author(s):  
Bertholdand Senftinger ◽  
Helmut Liebl
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Field Strength ◽  
Numerical Aperture ◽  
Low Energy ◽  
Energy Electron ◽  
High Resolution Imaging ◽  
Lens System ◽  
Resolution Imaging ◽  
Low Energy Electron

During the last few years the investigation of clean and adsorbate-covered solid surfaces as well as thin-film growth and molecular dynamics have given rise to a constant demand for high-resolution imaging microscopy with reflected and diffracted low energy electrons as well as photo-electrons. A recent successful implementation of a UHV low-energy electron microscope by Bauer and Telieps encouraged us to construct such a low energy electron microscope (LEEM) for high-resolution imaging incorporating several novel design features, which is described more detailed elsewhere.The constraint of high field strength at the surface required to keep the aberrations caused by the accelerating field small and high UV photon intensity to get an improved signal-to-noise ratio for photoemission led to the design of a tetrode emission lens system capable of also focusing the UV light at the surface through an integrated Schwarzschild-type objective. Fig. 1 shows an axial section of the emission lens in the LEEM with sample (28) and part of the sample holder (29). The integrated mirror objective (50a, 50b) is used for visual in situ microscopic observation of the sample as well as for UV illumination. The electron optical components and the sample with accelerating field followed by an einzel lens form a tetrode system. In order to keep the field strength high, the sample is separated from the first element of the einzel lens by only 1.6 mm. With a numerical aperture of 0.5 for the Schwarzschild objective the orifice in the first element of the einzel lens has to be about 3.0 mm in diameter. Considering the much smaller distance to the sample one can expect intense distortions of the accelerating field in front of the sample. Because the achievable lateral resolution depends mainly on the quality of the first imaging step, careful investigation of the aberrations caused by the emission lens system had to be done in order to avoid sacrificing high lateral resolution for larger numerical aperture.

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