.net barcode reader library Radio-wave intensity in Software

Printer ECC200 in Software Radio-wave intensity

Radio-wave intensity
Reading ECC200 In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Making ECC200 In None
Using Barcode printer for Software Control to generate, create DataMatrix image in Software applications.
The radio wave is attenuated (ie reduced in apparent power) as it propagates from the transmitter to the receiver Although at some very high microwave frequencies, there is additional path loss as a result of the oxygen and water vapor content of the air At other frequencies other losses exist Radio waves at all frequencies suffer losses due to the inverse square law Let s take a look at that phenomenon The electric field vector falls off in direct proportion to the distance traveled The E field is measured in terms of volts per meter (V/m), or in the subunits millivolts per meter (mV/m) or microvolts per meter ( V/m) That is, if an E field of
Recognize Data Matrix 2d Barcode In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
Generating Data Matrix 2d Barcode In Visual C#
Using Barcode printer for VS .NET Control to generate, create Data Matrix image in VS .NET applications.
90 E B
Generate Data Matrix ECC200 In .NET
Using Barcode creator for ASP.NET Control to generate, create Data Matrix image in ASP.NET applications.
Making ECC200 In .NET
Using Barcode printer for .NET framework Control to generate, create Data Matrix image in Visual Studio .NET applications.
Electric field Magnetic field
ECC200 Encoder In Visual Basic .NET
Using Barcode maker for .NET Control to generate, create DataMatrix image in .NET applications.
Bar Code Printer In None
Using Barcode drawer for Software Control to generate, create barcode image in Software applications.
Dire of tr ction avel
Make UPC - 13 In None
Using Barcode creation for Software Control to generate, create EAN-13 image in Software applications.
Making EAN / UCC - 13 In None
Using Barcode creation for Software Control to generate, create GS1 128 image in Software applications.
2-3 Electromagnetic wave consists of right angle electric and magnetic fields
Encode Code 3 Of 9 In None
Using Barcode maker for Software Control to generate, create Code 39 image in Software applications.
Paint DataMatrix In None
Using Barcode maker for Software Control to generate, create Data Matrix ECC200 image in Software applications.
10 Radio-wave propagation 10 V/m crosses your body from head to toe, and you are about 2 m tall, then an electrical voltage is generated of (2 m) (10 V/m), or 20 V The reduction of the E field is linearly related to distance (ie, if the distance doubles the E-field voltage vector halves) Thus, a 100 mV/m E field that is measured 1 mi from the transmitter will be 50 mV/m at 2 mi The power in any electrical system is related to the voltage by the relationship P= where P is the power in watts (W) R is the resistance in ohms ( ) E is the electrical potential in volts (V) In the case of a radio wave, the R term is replaced with the impedance (Z) of free space, which is on the order of 377 If the E field intensity is, for example, 10 V/m, then the power density of the signal is P= (10 V/m)2 = 0265 W/m2 = 265 mW/m2 377 [25] E2 R [24]
Creating 4-State Customer Barcode In None
Using Barcode creator for Software Control to generate, create Intelligent Mail image in Software applications.
Barcode Generator In None
Using Barcode creation for Microsoft Word Control to generate, create bar code image in Word applications.
The power density, measured in watts per square meter (W/m2), or the subunits (eg, mW/cm2), falls off according to the square of the distance This phenomenon is shown graphically in Fig 2-4 Here, you can see a lamp emitting a light beam that falls on a surface (A), at distance L, with a given intensity At another surface (B), that is 2L from the source, the same amount of energy is distributed over an area (B) that is twice as large as area A Thus, the power density falls off according to 1/d2, where d is the difference in distance This is called the inverse square law
DataMatrix Creator In Java
Using Barcode printer for Java Control to generate, create Data Matrix image in Java applications.
Data Matrix ECC200 Encoder In C#
Using Barcode generation for VS .NET Control to generate, create Data Matrix ECC200 image in Visual Studio .NET applications.
Isotropic sources
ANSI/AIM Code 39 Creator In Visual Basic .NET
Using Barcode creation for .NET Control to generate, create Code 39 image in Visual Studio .NET applications.
Code 128 Code Set C Generation In None
Using Barcode maker for Word Control to generate, create Code 128 Code Set C image in Office Word applications.
In dealing with both antenna theory and radio wave propagation, a theoretical construct called an isotropic source is sometimes used for the sake of comparison, and for simpler arithmetic You will see the isotropic model several places in this book An isotropic source assumes that the radiator (ie, an antenna ) is a very tiny spherical source that radiates energy equally well in all directions The radiation pattern is thus a sphere with the isotropic antenna at the center Because a spherical source is uniform in all directions, and its geometry is easily determined mathematically, the signal intensities at all points can be calculated from basic geometric principles For the isotropic case, you can calculate the average power in the extended sphere from Pt Pav = [26] 4 d2
Data Matrix ECC200 Scanner In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
Painting Code 128B In Objective-C
Using Barcode encoder for iPad Control to generate, create Code 128 Code Set B image in iPad applications.
The electromagnetic field: a brief review 11
Lamp A B
2-4 As a wave propagates, it spreads out according to the inverse square law, ie, the area of B is 4 times that of A because it is twice as far from the source
where Pav is the average power per unit area Pt is the total power d is the radius of the sphere in meters (ie, the distance from the radiator to the point in question) The effective aperture (Ae) of the receiving antenna relates to its ability to collect power from the EM wave and deliver it to the load Although typically smaller than the surface area in real antennas, for the theoretical isotropic case Ae = 2/4 The power delivered to the load is PL = Pav Ae [27]
By combining the two previous equations, the power delivered to a load at distance d is given by Pt 2 [28] PL = (4 )2d2 where PL is the power to the load is the wavelength (c/F) of the signal From these expressions, there can then be derived an expression for ordinary path losses between an isotropic transmitter antenna and a receiver antenna: LdB = 10 log Pt PL [29]
12 Radio-wave propagation or, by rearranging to account for individual terms: LdB = [20 log d] + [20 log FMHz ] + k where LdB is the path loss in decibels (dB) d is the path length FMHz is frequency in megahertz (MHz) k is a constant that depends on the units of d as follows: k = 324 if d in kilometers = 3658 if d in statute miles = 3780 if d in nautical miles = 3787 if d in feet = 2755 if d in meters The radiated sphere of energy gets ever larger as the wave propagates away from the isotropic source If, at a great distance from the center, you take a look at a small slice of the advancing wavefront you can assume that it is essentially a flat plane, as in Fig 2-5 This situation is analogous to the apparent flatness of the prairie, even though the surface of the earth is nearly spherical You would be able to see the electric and magnetic field vectors at right angles to each other in the flat plane wavefront The polarization of an EM wave is, by definition, the direction of the electric field Figure 2-6A shows vertical polarization, because the electric field is vertical with respect to the earth If the fields were exchanged (as in Fig 2-6B), then the EM wave would be horizontally polarized These designations are especially convenient because they also show the type of antenna used: vertical antennas produce vertically polarized signals, while hori[210]
Copyright © OnBarcode.com . All rights reserved.