D. I. Voskresensky - Dr.Sc. (Eng.), Professor, Head of Department of Radiophysics, Antennas and Microwave Technique of Moscow Aviation Institute (National Research University) E. V. Ovchinnikova - Ph.D. (Eng.), Associate Professor, Department of Radiophysics, Antennas and Microwave Technique of Moscow Aviation Institute (National Research University). E-mail: oea8888@gmail.com Bui Cao Ninh - Post-graduate Student, Department of Radiophysics, Antennas and Microwave Technique of Moscow Aviation Institute (National Research University). E-mail: buicaoninh@gmail.com Pham Van Vinh - Post-graduate Student, Department of Radiophysics, Antennas and Microwave Technique of Moscow Aviation Institute (National Research University)

Currently, the different types of wideband antennas are used for expansion of the functionality of modern mobile phones. They are the traveling wave antennas, mutually complementary structures, as well as various combinations of antennas of these two types. The required characteristics of a mobile phone are provided by multilayer wideband microstrip antenna of type \"butterfly\". In the design of such emitters, it is desirable to have relations, allowing to calculate the characteristics and to carry out the parametric optimization of the structure. The development of the rigorous theory of the radiation for the considered antenna is possible, but considering the features of the structure such as sharp corners, a small thickness of the plate and dimensions commensurate with the wavelength it is to be expected that the derived results are of little use for an approximate estimate of the emitter which doesn-t require the essential temporary expenditure and computer resources. Therefore, as in the theory of an ordinary dipole antenna, we can use the approximate theory in which the solution of the internal problem is based on the theory of long lines. The considered wideband microstrip antennas are performed on the sections of inhomogeneous line. It allows to apply the theory of such lines for an approximate estimate of directional properties and frequency characteristics of antennas. The theory of inhomogeneous lines is well known, but it is widely used only for calculating of characteristics of the feeder tract elements. The article describes the method of calculating the frequency characteristics of the antenna of a "butterfly" type. In accordance with this method, the antenna is presented in the form of an open inhomogeneous line with radiation losses. The influence of the law the line has been curved according with on the distribution of the line characteristic has been shown. The laws of distribution of current and voltage in a heterogeneous open line with losses have been determined. Because the shoulders of the antenna of a \"butterfly\" type are loaded on the stubs with the input impedance with the inductive character, the approximate model also includes the inductive stubs of the equivalent line with the wave of type T. The current distribution on shoulders of the antenna and the distribution of the resistance have been defined for the above described antenna model.

 

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