Kenichi Kakizaki

Near-Field to Far-Field Transformation for an Outdoor RCS Range

This paper presents the near-field to far-field transformation for an outdoor radar cross section (RCS) range. Direct measurement of the large actual target requires quite a long measurement range. The near-field to far-field RCS transformation method achieves the reduction of measurement range. However the non-uniformity of the incident electric field distribution on the target causes some errors in RCS prediction. We propose a novel near-field to far-field RCS transformation method that can be applied to an outdoor RCS measurement. The non-uniformity of the incident electric field distribution is successfully resolved by introducing the correction term of the ground bounce. We investigate the validity of the proposed method by the simulation and measurement.

Near-field to far-field transformation for RCS measurement including ground bounce

The authors propose a novel near-field to far-field radar cross-section RCS transformation method that is suitable for an outdoor RCS measurement. The validity of the proposed method is investigated by the simulation and measurement results.

Two resistors loaded ultra-wideband spiral array antennas

In this paper, we propose a new type of a small spiral antenna that has a pair of resistors and verify its ultra- wideband characteristics. Spiral antennas have ultra-wideband characteristics such as a nearly constant input impedance, antenna gain, and low axial ratio. However, when reflectors such as conducting planes or cavities are used, their performances are degraded due to reflections from the end of these spiral arms. In particular, this effect is remarkable at low frequencies where these antennas become small in comparison to their wavelengths. Therefore, new termination technique for small spiral antennas backed by a cavity, their array antenna performances were examined and showed high gain and low axial ratio characteristics.