A UWB impulse array antenna (IAA) utilizing a novel electrical scanning system with tapped delay lines is proposed and its usefulness is experimentally verified. The experimental antenna is composed of impulse generators installed in each antenna element and tapped delay lines used for creating transmitting trigger signals, which is a simple circuit configuration. It is shown that the output phase of the transmitting wave can be controlled by controlling the period of the trigger signal, and beam direction can be controlled from -30 deg to +30 deg by changing the trigger frequency from Fc-2 kHz to Fc+2 kHz. Evaluation of this antenna as a short range radar is carried out and distance resolution of 25 cm and angle resolution below 10 deg are obtained.

We fabricated and evaluated a prototype imaging system using the Simultaneous Frequency-Encoding technique, which is an active imaging technique that is potentially capable of fast frame-frequency imaging using a frequency-scanning antenna with only a single transceiver. The prototype performed simultaneous acquisition of pixels in elevation using Simultaneous Frequency-Encoding and performed a mechanical scan in azimuth. We also studied a ranging technique and incorporated it into the prototype. The ranging technique for Simultaneous Frequency-Encoding must take into account the characteristics of the frequency-scanning antenna, which are fundamental to Simultaneous Frequency-Encoding. We verified that ordinary range processing can be performed before frequency analysis with Simultaneous Frequency-Encoding, giving both range and angular profiles. The prototype was evaluated based on the radiation patterns of a receiver antenna comprising the frequency-scanning antenna and a reflector, on which both the image quality and ranging performance depend. Finally we conducted actual imaging tests and confirmed the capability of through-obstacle imaging. The frame frequency was only 0.1 Hz, which was due to the use of a slow mechanical scan in azimuth. However, assuming electronic beam forming is used instead of the mechanical scan, the frame frequency can be improved to several Hertz.

A novel structure for a composite right/left-handed (CRLH) corrugated waveguide in the millimeter-wave band is proposed. The CRLH waveguide is composed of a rectangular waveguide with tilted corrugations on its bottom broad wall. By operating above and below the cutoff frequency of the dominant mode of the rectangular waveguide, the CRLH waveguide provides, respectively, an inherent series inductance and shunt capacitance, and an inherent shunt inductance. Moreover, the tilted corrugations provide a series inductance and a series capacitance, which can support CRLH propagation. A frequency-scanning antenna using this CRLH waveguide is also studied numerically and experimentally. The results demonstrate that the antenna can provide backward-to-forward beam scanning, including the broadside direction. A scanning angle from -9.9 to +2.2 is achieved within a 1.8-GHz frequency range in the 60-GHz band.