THE BROADBAND VIBRATOR-LOOP ANTENNA
Timur A. Gainutdinov, Assistant professor, Cathedra of Technical Electrodynamics and Antennas, MTUCI, Moscow, Russia, tedia@mtuci.ru
Vadim G. Kocherzhewskiy, Senior lecturer, Cathedra of Technical Electrodynamics and Antennas, MTUCI, Moscow, Russia
Abstract
Wire antennas are one of the most widely distributed antennas of subscriber stations of broadband radio access systems. In many ways, the speed of information transmission in such systems limits the quality of antenna matching, which determines their working band. Since the antenna located at the mobile subscriber station must be comparatively compact, conventional methods of expansion of the matching field, involving an increase in the size of the antenna, in this case are unacceptable. The paper considers the methods of constructing comparatively compact wire antennas with a wide band of their own matching by the voltage standing wave coefficient (VSWR) not worse than 2. The results of optimization of the geometry of known simple wire antennas, such as dipole, loop vibrator and coil in order to expand their bandwidth are described. A method of constructing compact wire frequency-independent antennas in the form of a combination of simple electric and magnetic radiators with a single power supply is proposed. Combining into a single antenna structure two different directional and polarization properties of the radiators leads to the emergence of a number of problems, such as significant cross-polarization radiation and frequency instability of the main polarization pattern. As an illustration of the proposed method, the original designs of two vibratory-loop antennas with a wide band of their own coordination are given, one of which, having smaller dimensions, has a pronounced frequency dispersion of directional and polarization properties, and the second, with slightly larger dimensions, has these disadvantages, which are originally characteristic of hybrid designs. For both of the proposed structures, numerical results are given for the calculation of the frequency behavior of the input impedance and VSWR, the gain on the main and cross polarization, and a typical view of the radiation patterns in the field of antenna matching.
Keywords: VSWR, antenna natural matching, loop monopole, vibrator-loop antenna, cross-polarization radiation.
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Information about authors:
Timur A. Gainutdinov, Assistant professor, Cathedra of Technical Electrodynamics and Antennas, MTUCI, Moscow, Russia
Vadim G. Kocherzhewskiy, Senior lecturer, Cathedra of Technical Electrodynamics and Antennas, MTUCI, Moscow, Russia