By Boris Levin
The e-book bargains with theoretical and experimental examine of antennas. The presentation relies at the electromagnetic idea. It starts off with the idea of skinny antennas. skinny antennas signify one of many major different types of radiators, therefore the speculation of skinny antennas is the foundation of the antennas research.
Special consciousness is paid to the critical equation of Leontovich-Levin for a present alongside a instantly thin-walled steel cylinder, that is resembling the equation of Hallen with an actual kernel. including the research of varied forms of antennas, the booklet bargains with the issues of synthesis together with the production a wide-band radiator via picking out of the kinds and the magnitudes of targeted lots, 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 publication, together with the result of software of a reimbursement strategy for the security of people opposed to irradiation and structural beneficial properties of send antennas.
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Extra info for Antenna Engineering : Theory and Problems
37) where KI(z) is an extraneous emf. 38) where 4pjw eW(JI, z) = d2V( JI, z)/dz2 + k2V( JI, z), and JI(±L1) = 0. The right part of this expression contains three components in square brackets: the first component is the exciting emf, the second component is emf which takes the radiation into account, and the third component is emf caused by influence of the second radiator. 21), we present the currents JI(z) and JII(V) in the form of series in powers of small parameters c1 and c2, respectively.
It is equal to L Ú PI = Ez J( z)dz = J 2 (0)(ZA0 + Zg ) . 80) 0 Here ZA0 is the input impedance of the antenna in the case of a perfectly conducting ground. In the absence of losses in the wires, the active component of this impedance is equal to the radiation resistance. e. losses in the ground do not affect the radiation resistance. 79) is equal to PII = P1 + P2 + P3 + 2 jwW . 81) Ú (m H 2 ) + e E 2 dV are V total powers of the radiation, of the losses in the wires, of the losses in the ground, as well as the oscillating energy in the volume V.
J0 KM ( z)Y = j 60 Y cos kL where J0 H ( z) = j To find expansion parameter Y, magnitude y (z) is used. It is calculated as L y ( z) = J0 KM (V) exp(- jkR) . e. kL £ p / 2 , Ïy (0), Y=Ì y ( L l / 4), kL > p / 2 . Ó Such selection of the expansion parameter is caused by the fact that function y (z) is proportional to the ratio of vector potential Az(z) at point z on the antenna surface to current J(z) in the same cross-section. For that reason, function y (z) varies slowly along the antenna, or more precisely it is almost constant except for the segments near the wires ends.