Parameter study of ehf dual-band vibrator antennas with coaxial and two-wire shunts

Abstract

Subject and Purpose. Two types of new dual-frequency microwave antennas with coaxial and two-wire shunts are considered with a view to improve calculation methods of radio engineering and design parameters of the antennas of the kind. Methods and Methodology. The mathematical methods of equivalent long line and the method of integral equation and optimization of objective functions are used, involving set-point and current values of the voltage standing-wave ratios at the antenna input connectors in the two operating frequency bands. Results. The research and development results have been presented for two variants of dual-frequency (dual-band) vibrator antennas according to whether the shunts are placed inside metal radiating tubes or outside the central conductive rod of the antenna. The shunts are in coaxial and two-wire versions. As applied to the first antenna variant, the method of shunt length optimization upon a minimization of the objective functions yields desired values of antenna electrical parameters (voltage standing-wave ratio, radiation patterns, etc.). For the second antenna variant with both coaxial and two-wire external shunts and provided that the design and operation principle of these antennas are similar, conditions under which the double-frequency mode is possible have been determined for the first time. Conclusion. The proposed method of design and development of tubular dual-frequency vibrator antennas with coaxial shunts has been used to yield a two-frequency circular (elliptical) polarization turnstile antenna as part of sea buoys in the project "Ocean" of the National Space Agency of Ukraine and other spaceborne dual-frequency antennas. The new dual-frequency microstrip antenna discussed in this paper saves us significant drawbacks peculiar to the known dual-frequency antennas and can be used aboard spacecraft and other mobile objects due to its small size.