Yuichi Kimura

A two-beam slotted leaky waveguide array for mobile reception of dual-polarization DBS

Mobile reception of direct broadcast satellites (DBS) has been very popular and the number of vehicles with DBS receiving systems is also rapidly increasing in Japan. Low-profile, mass-produceable, beam-tilting and high-efficiency receiving antennas had been desired to this end. We developed a single-layer slotted leaky waveguide array antenna for the single-polarized DBS in Japan which satisfies all these requirements. A novel single layer feed structure is applied to the antenna, which consists of cascades of /spl pi/-junctions and radiating waveguides as shown. The cross slots are densely arranged on the broad wall of the radiating waveguides. The leaky wave radiates a circular polarized beam in a large tilting angle of about 45 degrees from the zenith. It is advantageous for mobile DBS reception since the antenna can be installed horizontally on the roof of vehicles. A mechanical system steers the antenna to track the satellite only in the azimuthal plane. Tracking is not necessary in the elevation plane, since the beam width of the antenna with a short radiating waveguide is broad.

Novel single-layer waveguides for high-efficiency millimeter-wave arrays

This paper presents the design of high-gain, high-efficiency and mass produceable planar arrays for millimeter waves using novel single-layer slotted waveguides. State of the art performance of three types of waveguides is surveyed. A model antenna realizes 35 dBi gain and 64% efficiency at 60.2 GHz.

A two-beam slotted leaky waveguide array for mobile reception of dual polarization DBS

Mobile reception of direct broadcast satellites (DBS) has been very popular and the number of vehicles with DBS receiving systems is also rapidly increasing in Japan. Low-profile, mass-produceable, beam-tilting and high-efficiency receiving antennas had been desired to this end. We developed a single-layer slotted leaky waveguide array antenna for the single-polarized DBS in Japan which satisfies all these requirements. A novel single layer feed structure is applied to the antenna, which consists of cascades of /spl pi/-junctions and radiating waveguides as shown. The cross slots are densely arranged on the broad wall of the radiating waveguides. The leaky wave radiates a circular polarized beam in a large tilting angle of about 45 degrees from the zenith. It is advantageous for mobile DBS reception since the antenna can be installed horizontally on the roof of vehicles. A mechanical system steers the antenna to track the satellite only in the azimuthal plane. Tracking is not necessary in the elevation plane, since the beam width of the antenna with a short radiating waveguide is broad.

Frequency characteristics of alternating-phase single-layer slotted waveguide array with reduced narrow walls

There are strong demands for high gain and mass produceable planar arrays at millimeter waves. However the planar arrays reported in the literature adopt microstrip or triplate lines as the feeder, which inherently suffer from serious losses at millimeter-wave frequencies. On the other hand, the transmission loss is so negligible for the waveguide that a slotted waveguide array antenna is a leading candidate for a high-gain flat antenna at millimeter-wave frequencies. The authors show two types of single-layer slotted waveguide array antenna; one is a co-phase type and the other is an alternating-phase one. The former has already achieved a high-efficiency and a high-gain performance at microwave frequencies, but is slightly degraded at millimeter-wave frequencies due to the incomplete contact between the slot plate and groove structure electrically. The electric contact is not important in the latter because no total currents flow across them. Furthermore, all the side-walls can be removed in principle at the center frequency. This reduced side-wall structure is expected to have higher-efficiency than the co-phase feeding type because reduction of side-walls reduces the loss as well as cost for fabrication. But the distance between null points of the guided standing wave and slots varies according to frequency changes. This results in a narrow antenna bandwidth. In this paper, characteristics of single-layer waveguides are surveyed in terms of efficiency and mass produceability. Secondly, bandwidth is evaluated for reduced side-wall antennas.

Low sidelobe single-layer slotted waveguide arrays at 76 GHz band

This paper presents a low sidelobe single-layer slotted waveguide array for car radar systems at the 76 GHz band. Both the array of the /spl pi/-junctions and that of the slot array are designed to realize the two-dimensional Taylor distribution. A target for the side-lobe level is -25 dB. Good radiation patterns with side-lobes below -24 dB are confirmed by the measurements in both E- and H-plane. High-gain and high efficiency of no lower than 34.5 dBi and 50% are preserved.

Chokes for alternating-phase fed single-layer slotted waveguide arrays

The alternating-phase fed array with the choke structure which dispenses with any contact between the slotted plate and the groove feed structure is discussed. It is demonstrated that the choke works very effectively to prevent the leakage in the feed waveguide and to keep the antenna efficiency high. A summary is included of the efficiency of various types of planar antennas as a function of antenna gain and frequency. The alternating-phase array achieves high-gain and high-efficiency performance in spite of the simple fabrication dispensing with any contacts.