By Boris Levin
The e-book offers with theoretical and experimental learn of antennas. The presentation relies at the electromagnetic concept. It starts with the speculation of skinny antennas. skinny antennas characterize one of many major forms of radiators, therefore the speculation of skinny antennas is the foundation of the antennas research.
Special awareness is paid to the crucial equation of Leontovich-Levin for a present alongside a directly thin-walled steel cylinder, that's akin to the equation of Hallen with an actual kernel. including the research of varied varieties of antennas, the publication offers with the issues of synthesis together with the construction a wide-band radiator via selecting of the categories and the magnitudes of targeted quite a bit, that are attached alongside a linear radiator and create in a given frequency band excessive electric functionality.
Problems of antenna engineering are mentioned within the moment half the e-book, together with the result of program of a repayment approach for the safety of people opposed to irradiation and structural positive aspects of send antennas.
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Extra info for Antenna Engineering : Theory and Problems
40) it follows that, when calculating the second and subsequent terms of the series, one can consider that the current of the first radiator is concentrated on its axis. 34) it follows that the current of the second radiator also is concentrated on the axis. 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.
This circumstance simplifies essentially the calculation based on the recurrent formulas. 20) allows to calculate the second approximation for the input current. 17) at a point z = 0 is equal to e c tan a . 20) at this point is L c2 J 2 ( 0 ) = j c sin a ÈÎK (V ) + EV ( cJ1 )˘˚ sin k ( L - V ) dV = c2 J21 (0) + c2 J22 (0). 22) 30 sin 2a Ú -L This value consists of two summands corresponding to two elements in square brackets. It is seen that the first summand is equal to cJ1(0). e. ZA0 is the known expression for the input impedance of the dipole, which was obtained by method of induced emf (second formulation).
E. the smallest of three magnitudes: wavelength l, antenna length 2L and the radius Rc of its curvature. e. 5 /ln(2 L / ae ). 12), we obtain the desired equation È ˘ d2 J d 2V 2 + = 4 + + k 2V ˙ . 14) This equation together with the components, which contain the extraneous emf, the current and the current derivative, also has the element incorporating the integral V( J, z) and its derivative. It is known that one concentrated emf cannot create the sinusoidal current along the dipole . The mentioned element is the additional emf, which depends on the current of the antenna.