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Telecommunications and Radio Engineering
SJR: 0.202 SNIP: 0.2 CiteScore™: 0.23

ISSN Imprimer: 0040-2508
ISSN En ligne: 1943-6009

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Telecommunications and Radio Engineering

DOI: 10.1615/TelecomRadEng.v76.i7.10
pages 557-577

ELECTRICALLY SMALL DIPOLE, HELICAL AND LOOP ANTENNAS

V. V. Ovsyanikov
Oles Honchar Dnipro National University 72, Gagarin Av., Dnipro, 49010, Ukraine

RÉSUMÉ

Results are presented of investigating the basic performance characteristics of electrically small, linear, wire microwave antennas that are characterized by essentially small dimension and weight. In the study both approximate and rigorous theoretical methods, as well as experimental techniques are used. The calculations are performed by approximate methods and rigorous technique of integral equation with the use of modern computer software packages super NEC, FEKO and others. A method of structural-parametric optimization and approximate analysis of such antennas with inductive and capacitive loads inserted into the radiating arms is first suggested. Approximate formulas are presented for estimating values of the reactive loads included into pin and loop bent antennas and determining their input impedances. Making use of these formulas, calculations of the values of inductive and capacitive loads have been performed which results are confirmed experimentally. Results of theoretical and experimental pioneered investigations of the Q-factor and efficiency of electrically small pin, helical and loop antennas with reactive loaded included into their arms are presented. As follows from the obtained results, bent pin antennas with the electrical sizes of their arm reduced to values 0.01...0.03 of the operating wavelength with respect to the arm size of the usual full-size antennas are characterized by the efficiency decreased to 20% and less with the Q-factor magnitudes lying within the limits from 130 to 1000. Also, the results of measuring the efficiency show that reduction of the electrical length of the antennas under investigation, both with inserted inductive loads and designed in the form of a cylindrical helix, by a factor of two with respect to the conventional size results in decreasing their efficiency from 100% to 75...85% as compared with the standard pin antennas. Shortening the electric length to a third leads to decreasing the antenna efficiency to 40...50%. A further shortening of the antennas of the kind is accompanied by further reducing their efficiency. The material presented in the paper can be useful for designing electrically small and diminutive antennas and antenna gratings of microstrip and other implementations.