Kazunari Kihira

Amplifier selection method of array feed element for achieving the minimum power consumption

Multibeam satellite systems with tens of spot beams have been developed and studied. A Multibeam satellite system realizes adaptive frequency allocation for efficient frequency reuse, and has the flexibility to control traffic in communication. When natural disasters happen, the communications traffics concentrate at the area because many people use cellular phones and access to the Internet. The corresponding beam to the area requires the highest output power operation in the emergency case. The amplifiers consist of the beam is operated at the required output power (ROP) in the emergency case. Generally, all amplifiers have the same maximum output power (MOP). However, not all the amplifiers require the same power as the MOP. The amplifier whose MOP is much higher than the ROP has low efficiency. In this paper, to minimize the power consumption of array-fed element, we propose the method how to select the MOP for each amplifier of antenna element of array antenna system.

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.

Dual frequency patch antenna using partially shorted annular ring patch antenna

In this paper, a dual frequency patch antenna using partially shorted annular ring patch antenna is proposed. The resonant frequency can be controlled by adjusting the number or the radii of the shorted pin, without changing the radiator size itself. Design and experimental results have good agreement, and the effectiveness is confirmed. The proposed dual-frequency antenna has minimum size, and the ratio of the two operating frequencies is small.

Adaptive array antenna using self-coherence property in Global Navigation Satellite Systems

This paper considers an adaptive array antenna for the interference suppression in Global Navigation Satellite Systems (GNSS). Two anti-jamming algorithms are proposed and these algorithms rely on the unique structure of the course/acquisition(C/A) code of the satellite signals. The effectiveness of those algorithms is presented by computer simulations.