No abstract

No abstract

No abstract

By signature gathering system, the shaft-frequency electric field of ship’s physical scale model is measured. At the same time, the mechanism of the corrosion related to shaft-frequency electric field is also described. Results show that the shaft-frequency electric field signature arises around a vessel and transmits in the surrounding seawater due to the current flow from impressed current cathodic protection (ICCP) system and the current flow resulting from the corrosion of dissimilar metals during propeller rotation, which contains both shaft fundamental and harmonics. The signature character of electric field is more and more marked with the shaft rotation speed increasing. The amplitude of electric shaft-frequency electric field by modulating the current of ICCP system is 10 times greater than that of corrosion current. It is proved that the using a 1:100 physical scale model of a vessel to study the shaft-frequency electric field character is an effective method and provided an new way.

The continuous beam scanning capability is a key characteristic of the reconfigurable antenna in wireless communication. In this work, we theoretically imply that the plasma columns are capable of smoothly manipulating the transmission of the electromagnetic waves. And then we propose a plasma-based microwave modulation method for obtaining a high precision beam scanning over 360 degrees on the azimuthal plane by tailoring the operating currents in 22-tube plasma window antenna system. Through this simple current modulation approach, a continuous beam scanning is achieved at the reconfiguration time of 0.6 ms without any detriment to the lobe shape.