Akira Akiyama

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.

Conical beam radial line slot antennas for 60 GHz band wireless LAN

In this paper, we fabricate a conical beam small aperture radial line slot antenna (RLSA) for a 60-GHz band wireless LAN. Measured results are also shown for demonstrating the feasibility.

Design of radial line slot antennas for millimeter wave wireless LAN

Discusses the design and fabrication of a concentric array radial line slot antenna for high speed wireless LAN applications in the 60 GHz band. Radiation patterns and gain are calculated. Calculations of the performance are also discussed.

A millimeter-wave radial line slot antenna fed by a rectangular waveguide through a ring slot

A radial line slot antenna (RLSA) is a high gain and high efficiency planar antenna proposed for DBS subscribers in the 12 GHz band. In recent years, several radio systems have been developed in the millimeter wave band. In conventional RLS, a radial waveguide has been fed by a coaxial feeder. In the millimeter wave band, fabrication of the feeder is considerably difficult, since the physical size is small. High accuracy in manufacturing is needed to give high antenna efficiency. We have proposed a planar feed circuit with a ring slot and a microstrip line (see Kigure, Y. et al., IEICE Natl. Conv. Rec., B-1-102, 1999). The feed circuit may be easily integrated with an RF planar circuit. In this structure, however, undesired radiation to the back of the antenna is significant and the antenna efficiency is degraded. In terms of efficiency in the millimeter wave band, a rectangular waveguide is more attractive for feeding a radial waveguide. A rectangular-to-radial waveguide transformer through a ring slot is proposed. This transformer is slightly bulky, however there is no leakage. It is suitable for integrating with existing RF modules that have an interface to the rectangular waveguide. The rectangular-to-radial waveguide transformer through a ring slot is designed and fabricated at the 12 GHz band and we integrate a RLSA with this feed circuit at the 38 GHz band.

Characteristics of 60 GHz band conical beam radial line slot antennas

Conical beam concentric array radial slot line antennas (RSLA) have been fabricated for the 60 GHz band. A PTFE substrate with copper foils is used. The coaxial feeder has been modified to improve the reflection. The measured reflection has revealed that the -15 dB bandwidth is about 500 MHz around the design frequency. The bandwidth of the gain has also improved because of the feeder modification.

Infrared image guidance for ground vehicle based on fast wavelet image focusing and tracking

We studied the infrared image guidance for ground vehicle based on the fast wavelet image focusing and tracking. Here we uses the image of the uncooled infrared imager mounted on the two axis gimbal system and the developed new auto focusing algorithm on the Daubechies wavelet transform. The developed new focusing algorithm on the Daubechies wavelet transform processes the result of the high pass filter effect to meet the direct detection of the objects. This new focusing gives us the distance information of the outside world smoothly, and the information of the gimbal system gives us the direction of objects in the outside world to match the sense of the spherical coordinate system. We installed this system on the hand made electric ground vehicle platform powered by 24VDC battery. The electric vehicle equips the rotary encoder units and the inertia rate sensor units to make the correct navigation process. The image tracking also uses the developed newt wavelet focusing within several image processing. The size of the hand made electric ground vehicle platform is about 1m long, 0.75m wide, 1m high, and 50kg weight. We tested the infrared image guidance for ground vehicle based on the new wavelet image focusing and tracking using the electric vehicle indoor and outdoor. The test shows the good results by the developed infrared image guidance for ground vehicle based on the new wavelet image focusing and tracking.

Space imaging infrared optical guidance for autonomous ground vehicle

We have developed the Space Imaging Infrared Optical Guidance for Autonomous Ground Vehicle based on the uncooled infrared camera and focusing technique to detect the objects to be evaded and to set the drive path. For this purpose we made servomotor drive system to control the focus function of the infrared camera lens. To determine the best focus position we use the auto focus image processing of Daubechies wavelet transform technique with 4 terms. From the determined best focus position we transformed it to the distance of the object. We made the aluminum frame ground vehicle to mount the auto focus infrared unit. Its size is 900mm long and 800mm wide. This vehicle mounted Ackerman front steering system and the rear motor drive system. To confirm the guidance ability of the Space Imaging Infrared Optical Guidance for Autonomous Ground Vehicle we had the experiments for the detection ability of the infrared auto focus unit to the actual car on the road and the roadside wall. As a result the auto focus image processing based on the Daubechies wavelet transform technique detects the best focus image clearly and give the depth of the object from the infrared camera unit.

Optical fiber imaging laser radar

We have developed the Optical Fiber Imaging Laser Radar based on the focal plane array detection using the small number of detectors less than the number of the focal plane array resolution. For this focal array detection, first, we made the optical fiber dissector which has one vertical cross section of the 35 x 35 optical fibers square array at one end to receive the reflected laser pulse from an object and 25 vertical cross sections of the 7 x 7 optical fibers array extracted from the 35 x 35 optical fibers square array at 25 other ends to guide the dissected laser pulse to the 25 InGaAs photodiode pulse detectors of the 25 channels of the parallel pulse counter. The 7 x 7 optical fibers arrays are the mode (5,5) residual classes from the 35 x 35 optical fibers square array. Second, we shaped the most of Erbium doped optical fiber laser pulse into the laser pulse with the beam of the elliptic cross section that falls into one 5 x 5 area of the vertical cross section of the 35 x 35 optical fibers square array when it is received. And we made a mask with a window of a size 5 x 5 optical fibers’ cross section to ensure no cross talk in the receiver of the Optical Fiber Imaging Laser Radar. Then, we controlled the direction of the shaped laser pulse to scan and reconstruct the received data from the 25 channels of the parallel pulse counter to the actual order data of the Imaging Laser Radar. The developed Imaging Laser Radar shows that the image resolution between the range image and the object is within one pixel difference and that the range resolution is under 15cm.

Stereo matching image processing by the fixed pixels period sampling edge detection and the characteristic band area construction

The stereo matching image processing is studied by the characteristic area properties, the geometrical restrictions and color comparisons. The characteristic areas are the 4 directional connectivity areas bound by the edge parts. The geometrical restrictions are the size difference ratio between the characteristic areas, matching point displacement ratio between the centers of the gravity of the characteristic areas, the size distortion ratio between the added stereo matching pattern union and the reference stereo matching pattern. The proper stereo matching conditions are the state of the maximum and sufficient large pixel number on the overlap area, the satisfaction of the condition of the average row difference ratio on the overlap area, the similar state of the average color difference on the overlap area on the proper combinations of the characteristic areas. The ability of the studied stereo matching is experimented with respect to the colorful soccer ball object. The result of the stereo matching experiments provide the proper correspondence between the centers of the gravity of the characteristic areas. The geometrical restrictions is effective to select the good combination between the characteristic areas of the stereo matching patterns.

Object silhouettes and surface directions through stereo matching image processing

We have studied the object silhouettes and surface direction through the stereo matching image processing to recognize the position, size and surface direction of the object. For this study we construct the pixel number change distribution of the HSI color component level, the binary component level image by the standard deviation threshold, the 4 directional pixels connectivity filter, the surface elements correspondence by the stereo matching and the projection rule relation. We note that the HSI color component level change tendency of the object image near the focus position is more stable than the HSI color component level change tendency of the object image over the unfocused range. We use the HSI color component level images near the fine focused position to extract the object silhouette. We extract the object silhouette properly. We find the surface direction of the object by the pixel numbers of the correspondence surface areas and the projection cosine rule after the stereo matching image processing by the characteristic areas and the synthesized colors. The epipolar geometry is used in this study because a pair of imager is arranged on the same epipolar plane. The surface direction detection results in the proper angle calculation. The construction of the object silhouettes and the surface direction detection of the object are realized.