Masataka Otsuka

Slotted waveguide array antenna covered by a dielectric slab with a post-wall cavity

In this paper, we propose a slotted waveguide array antenna covered by a dielectric slab with a post-wall cavity. The impedance matching of a resonant series slot array antenna based on a standing wave excitation can be easily achieved. Moreover, it is shown that the pattern shape of the proposed antenna is greatly improved and the directivity is enhanced by using the post-wall cavity.

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.

Sidelobe reduction of monopulse patterns using time modulated array antenna

A low sidelobe level pattern in the phased array antenna is desired for radar systems. The phase shifter control type time modulated array antenna has been investigated to achieve ultra-low side lobe pattern. In this method, a desired pattern can be accomplished in a time average procedure by temporally controlling of each element phase. For angle tracking radar, application of time-modulated array antenna for mono-pulse antenna (sum pattern and difference pattern are formed) has been studied. In this paper, a sidelobe reduction method of mono-pulse pattern based on the time-modulated array and phase offset procedure is proposed. The proposed method does not require additional hardware for the conventional mono-pulse antennas. The effectiveness of the proposed technique is demonstrated by computer simulation.