Alejandro Peralta

Power-amplifier modules covering 70-113 GHz using MMICs

A set of W-band power amplifier (PA) modules using monolithic microwave integrated circuits (MMICs) have been developed for the local oscillators of the far-infrared and sub-millimeter telescope (FIRST). The MMIC PA chips include three driver and three PAs, designed using microstrip lines, and another two smaller driver amplifiers using coplanar waveguides, covering the entire W-band. The highest frequency PA, which covers 100-113 GHz, has a peak power of greater than 250 mW (25 dBm) at 105 GHz, which is the best output power performance for a monolithic amplifier above 100 GHz to date. These monolithic PA chips are fabricated using 0.1-/spl mu/m AlGaAs/InGaAs/GaAs pseudomorphic T-gate power high electron-mobility transistors on a 2-mil GaAs substrate. The module assembly and testing, together with the system applications, is also addressed in this paper.

MMIC power amplifiers as local oscillator drivers for FIRST

The Heterodyne Instrument for the Far-Infrared and Sub- millimeter Telescope requires local oscillators well into the terahertz frequency range. The mechanism to realize the local oscillators will involve synthesizers, active multiplier chains (AMCs) with output frequencies from 71 - 112.5 GHz, power amplifiers to amplify the AMC signals, and chains of Schottky diode multipliers to achieve terahertz frequencies. We will present the latest state-of-the-art results on 70 - 115 GHz Monolithic Millimeter-wave Integrated Circuit power amplifier technology.

Transceiver array development for submillimeter-wave imaging radars

The Jet Propulsion Laboratory (JPL) is developing compact transceiver arrays housing discrete GaAs Schottky diodes with integrated waveguides in order to increase the frame rate and lower the cost of active submillimeter-wave imaging radar systems. As part of this effort, high performance diode frequency multiplier and mixer devices optimized for a 30 GHz bandwidth centered near 340 GHz have been fabricated using JPL’s MoMeD process. A two-element array unit cell was designed using a layered architecture with three-dimensional waveguide routing for maximum scalability to multiple array elements. Prototype two-element arrays have been built using both conventionally machined metal blocks as well as gold-plated micromachined silicon substrates. Preliminary performance characterization has been accomplished in terms of transmit power, and conversion loss, and promising 3D radar images of concealed weapons have been acquired using the array.

Solid-state terahertz sources for space applications

This paper discusses the construction of solid-state frequency multiplier chains utilized for terahertz receiver applications such as the Herschel Space Observatory. Emphasis is placed on the specific requirements to be met and challenges that were encountered. The availability of high power amplifiers at 100 GHz makes it possible to cascade frequency doublers and triplers with sufficient RF power to pump heterodyne receivers at THz frequencies. The environmental and mechanical constraints are addressed as well as reliability issues.

Bus development for a multitask engineering test satellite: SATEX

Multitask bus for small satellites is being developed at the University of Mexico (UNAM) for the conduction of LEO communications, remote sensing, and astronomical missions. The first prototype, SATEX-1, to be launched by Ariane in mid 1994, is a 50 Kg engineering test satellite with a primary communications payload and a CCD camera for low resolution imaging, as a secondary payload. SATEX-1 has been under design and development for several years and will be constructed by several research institutions, under finance from the Ministry of Communications (SCT/IMC). The structure is made of hybrid materials, including light aluminum alloys and composites. It has a three axis stabilization system. Attitude detection is realized by means of several sun and earth sensors. Electrical power is collected by two solar panels that are stowed for take-off, and deployed after separation. Thermal design is based mostly on passive components including radiators, shielding and orientation, but flat heaters are used in several places. Solid-state temperature sensors are used throughout the s/c to test and calibrate thermal models.

THz Instrumentation for the Herschel Space Observatory's Heterodyne Instrument for Far Infrared

The Heterodyne Instrument for Far Infrared (HIFI) on ESAs Herschel Space Observatory utilizes a variety of novel RF components in its five SIS receiver channels covering 480- 1250 GHz and two HEB receiver channels covering 1410-1910 GHz. The local oscillator unit will be passively cooled while the focal plane unit is cooled by superfluid helium and cold helium vapors. HIFI employs W-band GaAs amplifiers, InP HEMT low noise IF amplifiers, fixed tuned broadband planar diode multipliers, high power W-band Isolators, and novel material systems in the SIS mixers. The National Aeronautics and Space Administration through the Jet Propulsion Laboratory is managing the development of the highest frequency (1119-1250 GHz) SIS mixers, the local oscillators for the three highest frequency receivers as well as W-band power amplifiers, high power W-band isolators, varactor diode devices for all high frequency multipliers and InP HEMT components for all the receiver channels intermediate frequency amplifiers. The NASA developed components represent a significant advancement in the available performance. This paper presents an update of the performance and the current state of development.

Nonlinear order-statistic filters for image processing and restoration algorithms

Interactive analysis of massive data sets acquired by different remote sensors (RS) in microwave (MW), infrared (IR), and visible (V) bands requires special methods and algorithms. Different kind of noises and inaccuracies can deteriorate input data and give rise to considerable errors when an illposed inverse problem is solved. We are further developing a processing system to analyze multitemporal and multispectral images of different objects. The main advantages of this system are: the possibilities to restore 2D multispectral (multitemporal) images, and to find the highest correlation regions on an image produced by different sensors (MW: dm, cm, mm, SAR and non SAR; IR and V and oth) as well as the use of the new robust order-statistic filtering procedures proposed. Different RS problems have been investigated: rural or vegetation covered areas sensed by MW airborne sensors; forest fire areas, industrial plants in the night, electrical power elements (IR and V airborne sensors). Numerical simulation and experimental results have shown the efficiency of the proposed restoration and order-statistic filtering techniques.

Development of a digital videogrammetric airborne system

A system to conduct airborne remote sensing campaigns by means of CCD cameras and associated navigation and positioning equipment is presented. The system is under further development at the University of Mexico, but has been tested in several missions to evaluate its functional characteristics. The paper describes the various components of the system, such as cameras, aircraft mounting, pointing subsystem, GPS, location of view axis, real time monitoring and enhancement of ground details, as well as spectral filters and bands utilized, the interaction between obtained images, attitude data and a geographic information system for mosaic reconstruction, pilot navigation aids, and test polygons. The operation of the system has been demonstrated to be highly economical, reliable and relatively simple to use. It can also be fitted to various types of aircraft and helicopters, and may be used to conduct many types of missions such as: crop discrimination and mapping, urban settlement studies, land use charts, soil erosion evaluation, forest health, urban thermal island characterization, plant disease studies, and many more. A description of the flow of information from image capture to paper map is included, together with the methodology necessary to derive, from the images obtained, a multimedia system that handles a georeferenced data base for consultation by personnel of diverse backgrounds.

CCD image acquisition for multispectral teledetection

A low cost high-reliability multispectral video system has been developed for airborne remote sensing. Three low weight CCD cameras are mounted together with a photographic camera in a keviar composite self-contained structure. The CCD cameras are remotely controlled have spectral filters (80 nm at 50 T) placed in front of their optical system and all cameras are aligned to capture the same image field. Filters may be changed so as to adjust spectral bands according to the object s reflectance properties but a set of bands common to most remote sensing aircraft and satellites are usually placed covering visible and near JR. This paper presents results obtained with this system and some comparisons as to the cost resolution and atmospheric correction advantages with respect to other more costly devices. Also a brief description of the Remotely Piloted Vehicle (RPV) project where the camera system will be mounted is given. The images so obtained replace the costlier ones obtained by satellites in severai specific applications. Other applications under development include fire monitoring identification of vegetation in the field and in the laboratory discrimination of objects by color for industrial applications and for geological and engineering surveys. 1.

Large interactive database: design and implementation

A database system is being integrated in order to store and interactively retrieve information from a several hundred Gbytes optical memory. The low cost, high reliability requirements for the development and maintenance phase of the system suggested a modular design based on a network server, optical server, and some 40 (80386 based) viewing consoles with touch screens, but no keyboard or other controls since they are exposed to use by the general public. Optical disks store graphics, video, stills, text, animation, and audio which are accessed through hypertext and interactive graphics while a somewhat simple expert analyzes and records data on various aspects of the user, such as general interests, common questions, sociological-educational, background, etc. This information is in turn used to adapt several parameters of information display: rate of flow, language style, number and type of control buttons, degree of detail, and others. The large quantity of video, still images, and different graphics formats, has made it necessary to optimize the information contained via reduction of colors/resolution, compression techniques, and recursive use of a basic set of displays and video segments. The paper presents the design in some detail, with general examples of system capabilities, growth, and applications.