Larry Yujiri

Passive millimeter wave imaging

The use of the millimeter wave regime for imaging is becoming more widespread as a means for concealed weapons detection. A primer on the phenomenology of passive millimeter wave imaging will be presented to help explain how this imaging is accomplished with only ambient radiation. Examples of images acquired by passive millimeter wave cameras will be presented. A comparison between imaging indoors and outdoors will be made, highlighting the factors to be considered in both scenarios

W-band MMIC direct detection receiver for passive imaging system

W-band MMIC (monolithic microwave integrated circuit) direct-detection receivers for passive millimeter-wave imaging applications have been demonstrated. These receivers were developed using InGaAs HEMT (high electron mobility transistor)-based W-based LNA (low-noise amplifier) and preamplified detector MMICs. The first receiver uses a 50-dB-gain, 6-dB-noise-figure amplifier and a Schottky-barrier-diode waveguide detector. The amplifier uses four W-band MMIC LNAs. The second receiver consists of two three-stage MMIC LNAs and an MMIC preamplified detector chip. Individual receivers were integrated with a millimeter-wave camera system. Field imaging acquisition runs were performed using the camera in stepping pushbroom image acquisition mode, and excellent results were obtained.<<ETX>>

Large scale W-band focal plane array for passive radiometric imaging

This paper discusses the development of a large scale W-band focal plane array (FPA) for passive radiometric imaging application. The goal is to develop a 40/spl times/26 (1040-pixels) FPA to cover 15/spl deg//spl times/10/spl deg/ instantaneous field-of-view. Each receiver consists of a single direct detection MMIC which is a W-band high gain, wide bandwidth switched LNA with integrated Schottky barrier diode detector. A 1/spl times/4 FPA module, employing linearly tapered slot antenna, is used as the basic building block for the FPA. Typical receiver temperature sensitivity is 0.4 K with 10 ms integration time. For the first time, an automated assembly process is used to produce W-band MMIC modules in large volume.

Passive millimeter wave sensors for detection of buried mines

The detection of land mines and other ordnance on the battlefield has grown in importance with their increased use, not only for military personnel, but for civilians after hostilities have ceased. The need for new approaches and sensors to increase the speed and efficiency of methods to clear mines is an issue that must be addressed. A method to detect metal mines, on top of or buried under dry sand, is demonstrated using the passive detection of naturally occurring millimeter wave radiation (at 44 GHz) emanating from the scene. Measurements will be shown that indicate the feasibility of detection of metal under at least 3 inches of dry sand.

A passive millimeter wave camera for aircraft landing in low visibility conditions

Fog and low visibility conditions have hampered aviation since its inception. Fog-related accidents are numerous, and canceled take-offs and landings due to fog and low visibility conditions (Cat III) have significant economic impact on airlines, parcel carriers and general aviation. Millimeter waves have good propagation properties in weather and give adequate spatial resolution when used to image the forward scene. Passive millimeter wave focal plane array cameras are new sensors which, integrated into future guidance and landing systems, promise to be an effective aid, or alternative, to existing technology for aircraft landings and take-offs under Cat III conditions. They can produce visual-like radiometric images at real time frame rates (up to 30 Hz), and are directly amenable to image fusion with infrared and visible images. TRW has been actively involved in developing and productizing this technology both at the hardware and the system levels. >

Passive millimeter-wave video camera

A passive millimeter-wave (PMMW) camera capable of generating a real time display of the imaged scene, similar to video cameras, has been developed at TRW and is undergoing field testing. The camera operates at 89 GHz, acquiring images at a frame rate of 17 Hz. This work reports on the video imaging generated by the camera. This research is carried out under the Passive Millimeter-Wave Camera Consortium, a cost-shared program between the Defense Advanced Research Programs Agency and an industrial consortium that includes Honeywell, McDonnell Douglas and TRW. It is managed for the Department of Defense by NASA-LaRC.

Passive millimeter-wave camera flight tests

TRW has developed a passive millimeter wave demonstration camera using its unique millimeter wave monolithic integrated circuit (MMIC) technology. It operates in a 10 GHz band around 89 GHz, has a field of view of 10 degree(s) by 15 degree(s), and can process and display data in real-time at video rates. Its focal plane consists of 1040 MMIC direct detection receivers.

Large-aperture passive millimeter-wave pushbroom camera

TRW has developed a new passive millimeter wave camera for the Navy using its unique Millimeter Wave Monolithic Integrated Circuit (MMIC) technology. It operates as a pushbroom or scanning imager and can be utilized for missions that do not require as rapid a frame rate as in video-rate imagery. It is designed as a large-aperture, wide-field-of-view camera. Its focal plane consists of two rows of MMIC-based direct detection receivers and provides full sampling of the imaged scene.

Detection of land mines via a passive microwave radiometer

The concept of using passive microwave radiometers for the detection of buried objects is well rooted in the theory of radiation propagation through lossy media. As the dielectric discontinuity at the boundary layer between the foreign object and the soil cause a reflection of the incoming radiation,the object present different radiometric properties than the surrounding background, and becomes detectable as a change in the antenna temperature. Under a contract from the US Armys Night Vision and Electronics Sensors, TRW has designed and built two hand-held man- portable units, which employ the cold radiometric sky as the illuminating source. The units work at 1.7 and 5 GHz using direct RF-gain, total-power radiometers. The units were field-tested at the Army facility at Fort AP Hill during October of 1998. The test yielded a very exciting detection rate of 100 percent and a false alarm rate of 0.28/m2.

Large scale W-band focal plane array developments for passive millimeter wave imaging

A state-of-the-art W-Band passive millimeter wave focal plane array (FPA) consisting of 1040 highly integrated direct detection pixel has been designed, developed, assembled and tested. The FPA has been integrated into a passive millimeter wave video camera and has generated real time images. Each pixel is a highly integrated MMIC chip receiver. The MMIC chip is a wide band, high gain, low noise, 0.1 micrometer InGaAs HEMT amplifier with an integrated switch and Schottky barrier diode detector. The FPA uses a brick architecture. Each brick or module consists of 4 MMIC chips or pixels and lay side-by- side on the card. Many cards are stacked to create the array of pixels. In the next generation FPA, the 1 X 4 modules and cards have been dramatically simplified with 50% less assembly time. In addition, the module and card still require no tuning and minimal test time. Thus a significant cost reduction in the FPA is expected over the first generation FPA without sacrificing performance. To further reduce cost and improve performance, new MMIC chips are being designed.