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Journal Antennas №5 for 2016 г.
Article in number:
Analysis of current modes of a circular loop antenna
Keywords:
circular loop antenna
current distribution
integro-differential equation
Green function
thin-wire approximation
current mode
long line
Authors:
P. A. Mozgovoy - Ph.D. (Eng.), Head of Sector, JSC \"Concern \"Sozvezdie\" (Voronezh). E-mail: pamvrn@mail.ru
Abstract:
The purpose of this work is to obtain an analytic expression describing the current distribution along the wire circular loop antenna having a physical meaning and allowing a clear physical interpretation. The solution held in \"stranded\" approach. The vector potential of circular loop antenna current is represented as the sum of the vector potential current rectilinear vibrator and the difference of the vector potential. The difference of the vector potential is generated by the distinction the emitter topology from a straight line. The differential equation for the vector potential of the vibrator solved by the method of variation of constants. The resulting solution is transformed into an integral equation. To solve the integral equation allocated quasi singularity of the Green\'s function of the problem and introduced the small parameter of the problem that led to the trinomial formula for the stream function.
According to the analysis of this formula it is established that the total antenna current formed the feeder, loop and dipole modes. The feeder and loop modes inherent in a closed ring radiator (loop antenna), dipole fashion - open the ring radiator (vibrator) of the antenna conductor. Adding loop and dipole modes to the original feeder there is a compensatory response of the electromagnetic field of the current short-circuited two-wire line to its transformation into a circular loop antenna. The prevailing mode as part of the total current antenna is an antenna feeder mod. Additional modes make the largest contribution to the total current at the voltage resonance, and the smallest - at resonance current. The real part of the input impedance of the loop antenna is formed ring feeder and to a lesser degree loop modes, the main contribution to the imaginary part - gives feeder mod. The dipole mode is not involved in the formation of the input impedance, as vanishes at the point antenna feed.
The circular loop antenna is equivalent set of the ring loop and a ring oscillator formed by the conductor of the antenna, with the EMF power in diametrically opposite points.
The article includes 4 figures and references to 15 information sources.
Pages: 39-48
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