By Boris Levin
The ebook bargains with theoretical and experimental study of antennas. The presentation is predicated at the electromagnetic thought. It starts off with the speculation of skinny antennas. skinny antennas signify one of many major forms of radiators, hence the idea of skinny antennas is the root of the antennas research.
Special realization is paid to the necessary equation of Leontovich-Levin for a present alongside a immediately thin-walled steel cylinder, that's comparable to the equation of Hallen with an exact kernel. including the research of assorted different types of antennas, the publication offers with the issues of synthesis together with the production a wide-band radiator via making a choice on of the categories and the magnitudes of focused lots, that are hooked up alongside a linear radiator and create in a given frequency band excessive electric functionality.
Problems of antenna engineering are mentioned within the moment 1/2 the publication, together with the result of program of a repayment technique for the safety of people opposed to irradiation and structural gains of send antennas.
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Additional resources for Antenna Engineering : Theory and Problems
Resistance per unit area is R0 = 1/( ss) = 11p / sl , where s is the depth of current penetration into the ground and s is the conductivity of the ground. 75) is the antenna radius or the radius of the ground, whose conductivity can be considered infinitely great. The upper limit b must tend to infinity. It is easy to see, however, that in this case, the integral diverges. Indeed, the magnetic field of the monopole in the form of a thin conductive filament, mounted vertically on the perfectly conducting ground, can be written as Hj 0 ( r ) = j ( ) J (0 ) Èexp - jk r 2 + L2 - cos kL exp(- jk r )˘ .
21) accuracy level (accuracy of order of a1/L1) is retained. This circumstance simplifies essentially calculating members of the series for the current based on the recurrence formula, in particular the calculations of the terms n and (n – 1), since this formula allows calculating these fields as the fields of the filaments. 41) as the first term. It is interesting to compare the results of solving Leontovich-Levin equation for one and two radiators with solutions obtained by the induced emf method.
36). 2). Three components in the right part of the equation correspond to the exciter emf, to the radiation, and to the presence of the distributed load, respectively. As before, we shall seek the solution as a series in powers of small parameter c, presenting the surface impedance as 2jkZ(z)/(aZ0) = c–1U. That allows obtaining the set of equations for the not resonant radiator: d 2 J1 ( z) dz 2 d 2 J n ( z) dz 2 + k12 J1 ( z) = -4p jwe K ( z), J1 (± L) = 0 , + k12 Jn ( z) = -4p jweW ( Jn -1 , z), Jn (± L) = 0 , n > 1.