By Boris Levin
The ebook offers with theoretical and experimental examine of antennas. The presentation is predicated at the electromagnetic conception. It starts off with the idea of skinny antennas. skinny antennas characterize one of many major forms of radiators, therefore the idea of skinny antennas is the foundation of the antennas research.
Special cognizance is paid to the quintessential equation of Leontovich-Levin for a present alongside a instantly thin-walled steel cylinder, that's reminiscent of the equation of Hallen with an exact kernel. including the research of varied different types of antennas, the ebook bargains with the issues of synthesis together with the construction a wide-band radiator through picking out of the kinds and the magnitudes of centred 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 e-book, together with the result of program of a reimbursement procedure for the safety of people opposed to irradiation and structural beneficial properties of send antennas.
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Extra info for Antenna Engineering : Theory and Problems
Outside the boundaries of this area the component of zonal current, which decreases with increasing distance in accordance with the law 1/r, is dominated. This component is taken into account, when the radiation resistance is calculated. Inside the indicated area, the induction component of zonal current, which decreases according to the law 1/r2, is dominant. It is believed that this component causes losses in the ground. These qualitative considerations were a cause for quantitative evaluation, justifying actually arbitrary choice of the upper limit.
N=1 ¯ Â Then cn Jn ( z) = j L ÏÔ È Ê n -1 m ˆ ˘ c Í sin k ( L + z ) K ( V ) + E c Jm ˜ ˙ sin k(L - V )dV +, Ì VÁ 30 sin 2a Ô Í Ë ¯ ˙˚ m = 1 zÎ Ó ¸Ô È Ê n -1 m ˆ ˘ ÍK (V ) + EV Á c Jm ˜ ˙ sin k(L + V )dV ˝ . 19) 32 Antenna Engineering: Theory and Problems In particular, if n = 2, L c ÔÏ c J 2 ( z) = j Ìsin k(L + z) ÈÎK (V ) + EV ( cJ1 )˘˚ sin k(L - V)dV + 30 sin 2a Ô z Ó Ú 2 ¸Ô z sin k (L - z) Ú ÈÎK(V ) + E ( c J )˘˚ sin k(L + V )dV ˝Ô . 20) ˛ -L Here a = kL. 15) for the current and accordingly nth approximation, if (n–1)th approximation is known.
39). The fulfillment of the conditions is necessary to avoid possible mistakes. 49): (n) ZAI ª 1 L1 Ú ÈÎE ( J 2 JI(n -1) (0) - L1 s ( n -1) I ) + E (J s ( n -1) II )˘˚ J ( n -1)* (s )ds I . 49). But for that, the equality J1(1) (s) = - J1(1)* (s) must be accomplished. e. there should be no losses in the radiator and in the environment. From the foregoing it follows that in the analysis of the methods of calculating characteristics of the antenna it is necessary to take into account that in the second and subsequent approximation the current along the antenna wire contains not only reactive but also active component.