Narihiro Nakamoto

Poly-polarization Multiplexing Scheme for Satellite Communications

This paper proposes a novel transmission scheme that enhances the spectrum efficiency by exploiting multiple polarization planes. Unlike the conventional polarization usage that secures orthogonality, the proposed scheme transmits signals through more than 2 polarization planes and enhances spectrum efficiency in proportion to the number of the polarization planes. Degradation caused by cross polarization interference is restored by applying digital signal processing techniques. As a result of computer simulations, we have clarified that the proposed scheme improves required Eb/N0 by about 1dB and 1.4dB without / with FEC, respectively, when three polarizations are simultaneously transmitted.

A method to measure the antenna mode and structural mode for antenna RCS reduction using circulator and phase shifter

An antenna RCS reduction using circulator and phase shifter is one of promising RCS reduction techniques. In this RCS reduction method, the antenna mode scattered field, which is the re-radiated field of antenna, is controlled by the phase shifter to cancel out the structural mode scattered field. In this paper, a method is proposed to measure the amplitude and phase relationship between the antenna mode and structural mode for the deterministic RCS reduction. The effectiveness of the proposed method is verified by experiments using an array antenna with circulators and digital phase shifters.

Ultra wide band dual polarized tapered slot array with nested sub band elements

In this paper, an ultra wideband(Over 18:1 bandwidth) and dual polarized shared aperture taper slot antenna is proposed. The proposed antenna is composed of low band and high band elements, and the high band elements are arranged between the low band elements to achieve smaller aperture of antenna. The feasibility of the proposed antenna is shown through numerical simulation and experiments.