PHASE II: Develop/fabricate multi-band/beam receive modules. Demonstrate module operation including the required RF (Radio Frequency) and cross polarization isolation between channels.
DUAL USE COMMERCIALIZATION: Commercial interest in multi-band/beam communications is presently evolving from handheld cellular systems to higher frequency commercial markets. High isolation packaging techniques are also expanding in the commercial market. In this phase, the low cost, high isolation packaging techniques derived in prior phases will be leveraged into commercial applications and lower production cost multi-band/beam military modules.
REFERENCES:
KEYWORDS: Millimeter Wave Modules, EHF, Phased Array, Isolation, Multi-Beam,
Multi-Band
AF04-217 TITLE: Synchronized Space Object Tracking
TECHNOLOGY AREAS: Sensors, Electronics, Battlespace
OBJECTIVE: Develop better search, track and identification system performance characteristics especially for items with small cross sections or hard to see designs, such as wind patterns or stealthing objects, or to track larger objects with less transmit power, such as automobiles in a collision avoidance system. Do it without having to resort to a costly monolithic radar system. Using this next generation of a low cost, synchronized radar constellation, increase detection and tracking capabilities to accurately find and monitor objects of interest with half of the cross section and half the Signal to Noise Ratio (SNR) currently required or better, or use less than half the current power to detect current targets.
DESCRIPTION: Develop a suite of signal processing algorithms, and software to coordinate multiple receive, and possibly multiple transmit stations to inter-operate synchronously. Develop a tool that translates needed performance into number of synchronized units, dis-location distances, angular placement and power levels required to achieve the performance gains. The goal for the new hardware is to only use currently available commercial-off-the-shelf components when fabricating the new transmit and receive stations. Two immediate products are envisioned, one is a transportable receive only unit that can be quickly connected to one of many existing civilian or military radar systems to provide enhanced coverage from that system. Only systems that can record beam return data and subsequently transfer that data to our system are candidates for this product. The target results will be provided in near-real time. The second is a new set of transmit and receive stations which can interconnect with each other and will provide results in real time.
PHASE I: Identify the most promising equations for target detection using more than one radar site’s received beam data. Determine the best method for beam data analysis to maximize target detection with minimum SNRs. Develop the requirements necessary to allow effective synchronization between multiple receivers/transmitters. Engineer a computer nomogram which translates the required power levels and return characteristics into placement and configuration parameters for multiple receive units.
PHASE II: Implement a transportable receiver and find a cooperative existing radar system that can supply us with beam data in near-real time. Develop the interface components necessary to acquire synchronization and beam data. Using several positions validate the nomogram software. Summarize the results and lessons learned from this stage. Postulate whether multiple transmitters in conjunction with multiple receivers will increase performance characteristics. Using this information engineer the common components necessary to synchronize and coordinate any radar system and to provide for the integrated transmit and receive real-time products.
PHASE III: With the integrated transmit and receive real-time product designs, enter into agreement(s) with major radar developer(s) to produce a line of low-cost, low-power, mobile and mostly remote-controlled radar components which can be ganged together as necessary. These systems will be used in air traffic control, various academic studies such as asteroid locating/cataloging, weather pattern identification and automated transportation systems.
REFERENCES:
1. Kevin M. Cuomo, Jean E. Piou, Joseph T. Mayhan, “Ultra-Wideband Sensor Fusion For BMD Discrimination”, 2000 IEEE International Radar Conference (0-7803-5776-0/00)
US Army Space and Missile Defense Command, Sensor Analysis Division, results under Air Force contract F19628-95-C-0002.
2. De Elia, R. and I Zawadzki, “Sidelobe contamination in bistatic radars”, J. Atmos. Oceanic Tech 2000.
3. Protat, A. and I Zawadzki, “A semi-adjoint method for real time retrieval of three dimensional wind field from multiple-Doppler bistatic radar network data”, J. Atmos. Oceanic Tech 1999, 16, 432-449.
4. S. Sivananthan, T. Kirubarajan and Yaakov Bar-Shalom, “Radar Power Multiplier For Acquisition of Low Observables Using an ESA Radar”, IEEE Transactions on Aerospace and Electronic Systems, VOL 37, No. 2, April 2001.
KEYWORDS: Radar Sensors, Electro-Optical Sensors, Space/Upper Atmosphere Environment, Space Object Tracking, Space Situational Awareness, Space Object Catalog, Electronic Counter Counter Measures
AF04-218 TITLE: Efficient High Frequency Electromagnetic Source for Communication Devices
TECHNOLOGY AREAS: Space Platforms
OBJECTIVE: Manufacture high power/high frequency EM (electromagnetic) source generation that will enhance or replace TWT technology
DESCRIPTION: The availability of a new technology that utilizes lighter weight, smaller, compact techniques such as focused local plasma generation and much more efficient electron sources will have numerous applications in military and commercial systems. Present structures have design and construction principles developed over 50 years ago. They are large and energy inefficient. New materials and nano-fabrication principles have been identified that have the potential to significantly impact the development of future space communication components and systems. This SBIR topic seeks to develop the technology for the manufacture of EM sources that accomplish present requirements of frequency and power-out with volume and power-in parameters significantly less. The goals are to develop the technology and scientific underpinning that is required to fabricate such TWT (Traveling Wave Tube) equivalents and to provide the infrastructure for their manufacture and insertion into military and commercial applications.
PHASE I: Design/fabricate prototype to demonstrate the concept of the conventional TWT replacement. Power-in requirements should be improved by at least 5-10% and size and weight reductions > 50% over present state of art. Design and develop approach to replace magnetic focusing with alternative such as electron beam focusing via plasma manipulation, reducing weight and improving efficiency. Gather and analyze performance data on prototype cold cathodes. Develop a theoretical model to improve the efficiency of the device.
PHASE II: Refine the design and materials system to enhance the efficiency, reliability and output of the new EM source device. Use model predictions and actual measurements on prototype to design/fabricate an engineering model device. Prepare a manufacturing and commercialization roadmap to market the technology.
DUAL USE COMMERCIALIZATION: A superior transmitter source offers numerous opportunities for enhancement in both military and commercial applications. It would impact display efficiency and compactness and medical imaging for example.
REFERENCES: 1. E. G. Wintucky, et al, Proceedings of the Second International Vacuum Electron Sources Conference, Tskuba, Japan, Tskuba Information Laboratory, Inc., 1998
2. C.Ribbing, et al, “Miniature X-ray Sources with Diamond Electrodes”, 8th International Conference New Diamond Science and Technology, July 2002, The University of Melbourne, Australia
KEYWORDS: electron sources, cold cathode, traveling wave tubes, plasma focusing, field emission, field emitters.
AF04-219 TITLE: Signal Processing and Amplifier Design for Non-Constant-Envelope Modulation
TECHNOLOGY AREAS: Sensors, Electronics, Battlespace
OBJECTIVE: Minimize effective losses in power and spectral efficiency of Milsatcom systems due to nonlinear power amplifiers.
DESCRIPTION: The ever-increasing demand for higher data rates coupled with fixed allocations of bandwidth requires the use of higher order (non-binary) modulation techniques in Milsatcom systems. Unfortunately, many high order modulation techniques do not result in constant envelope waveforms and consequently result in undesirable signal properties at the output of nonlinear power amplifiers. The undesirable properties include both distortion of the amplified signal and emissions outside the desired frequency band. Amplifiers of interest operate in the frequency range from 7 to 45 GHz, with between 4 and 7 percent bandwidth, and at power levels from 1 to over 100 W. A conventional solution is to operate the amplifier in a range over which the characteristics are linear at the cost of decreased amplifier efficiency. Two possible approaches (among others) to this problem are: (1) signal processing techniques such as predistortion and equalization; or (2) development of a power amplifier with a greater degree of linearity. Some of the undesirable characteristics can be prevented or mitigated with the use of signal processing algorithms prior to amplifying the signal. Techniques such as predistortion have been developed to linearize the output of amplifiers, but further work is needed to create techniques that work well with higher order modulations such as 64-ary quadrature amplitude modulation (QAM) and pulse-shaped phase-shift keying (PSK). Equalization at the receiver may also provide benefits to performance. The algorithm development should not be limited to a single amplifier model. Furthermore, performance needs to be demonstrated using real components, not only simulations. In conjunction with signal processing algorithms, it is also desirable to investigate the construction of amplifiers that are more linear than current models. The end result of this study should include a number of techniques to reduce the effects of non-linear amplifiers. The criteria used to evaluate the proposed solutions shall include the performance of the desired signal as well as interference caused to signals in adjacent frequency bands.
PHASE I: In depth analysis of current high-power amplifier technology, including traveling wave tube amplifiers (TWTA) and solid state power amplifiers (SSPA). Analytical models, from literature searches and as a result of experimental measurements, shall be compared. Signal processing solutions and new linear amplifier designs shall be conceived and evaluated through analysis and simulation. The Phase I goal will be to select/present a short list of potential solutions for Phase II evaluation and demonstration.
PHASE II: Consist of evaluating/demonstrating the techniques proposed in Phase I using actual hardware. The effectiveness of each proposed solution must be evaluated and documented. Basic hardware shall be designed/fabricated and advanced demonstrations conducted for one or two selected solutions.
DUAL USE COMMERCIALIZATION: Technology developed under this program is appropriate for all forms of satellite communications, both military and commercial, and a wide variety of other commercial applications, such as terrestrial wireless communications, including cellular and personal communications systems.
REFERENCES:
KEYWORDS: Communications, SATCOM, Amplifier, Signal Processing, Predistortion, Quadrature Amplitude Modulation.
AF04-220 TITLE: Manufacturing Technology for Conformal Arrays
TECHNOLOGY AREAS: Sensors, Electronics, Battlespace
OBJECTIVE: Develop novel manufacturing techniques for producing multi-layer microstrip antennas and arrays conformal to the body of a high performance aircraft.
DESCRIPTION: One technique for meeting the future satellite communications needs of high performance military aircraft is to create antenna arrays conformal to the aircraft surface. Antenna arrays that are low profile and flush-mounted to the aircraft surface can provide significant advantages in terms of size and weight reduction without affecting the aerodynamic performance of the vehicle. Unfortunately, current techniques for making conformal antennas are difficult to apply to high performance aircraft. While conformal substrates can be directly molded onto small, regularly shaped objects such as cylinders and cones, large, irregular and doubly-curved surfaces such as those found on the wings and tail of an aircraft are more difficult to populate with antenna substrates and radiating elements. Experimental models of conformal aircraft antennas are typically made by etching the antenna onto very thin, flat, pc-board type substrates, bending the substrate around a stiff frame, and then bolting or gluing it in place. While this technique may be acceptable for antennas on singly-curved surfaces with large radii of curvature, it presents severe problems when applied to surfaces with small radii of curvature, doubly-curved objects, or multi-layer configurations. To be bent around tight curves, the antenna substrates must be soft and very thin. This limits the choice of substrates and also results in very narrow antenna bandwidths. In addition, bending of the substrate can produce tiny micro-cracks in the dielectric or the copper, which can affect the radiation pattern. The bolts and adhesives used to mount the antenna can also affect the radiation pattern, and present serious problems with the structural integrity of the aircraft. To overcome these difficulties, new technologies and processes need to be developed to produce thick, low loss, dielectric substrates and broadband, multi-layer microstrip antennas on large, doubly-curved surfaces. These technologies must produce conformal arrays that satisfy both the electrical and aerodynamic requirements of future airborne satellite communications systems.
PHASE I: Include the following tasks: 1) Select a candidate substrate and manufacturing process for building a single layer conformal microstrip patch array on a curved surface. The selected substrate should have the appropriate electrical and mechanical properties to provide acceptable antenna performance at microwave frequencies (low loss, low dielectric constant, uniform and isotropic), while maintaining the structural integrity of the aircraft. The process should be applicable to a C-band antenna conformal to a five-foot scale model of an aircraft wing, with exact dimensions to be provided by the Air Force.
2) Describe in detail the manufacturing process. The process may consist of any combination of techniques including extrusion, molding, machining, melt processing, spraying, painting, or other methods of the offeror's choosing. Discussion of the process shall include such factors as ease of fabrication, cost, controllability of the material properties (dielectric constant, loss, thickness, uniformity, etc.), manufacturing tolerances, health and environmental factors, and any other details which are critical to the process and the performance of the resulting antenna.
3) Perform detailed analyses of the mechanical and electrical properties of the conformal array, including effects on both aircraft and antenna performance. Factors to be evaluated include dimensional, mechanical, and thermal stability, layer-to-layer adhesion, substrate thickness, material losses, isotropy and uniformity, antenna bandwidth, radar cross section, and aerodynamic effects.
4) Demonstrate the feasibility of the process by fabricating and testing a small scale (single antenna element) prototype in a single layer configuration(ground plane, dielectric, radiator).
5) Describe methods for extending this process to produce multi-layer antennas with at least two dielectric substrate layers and two patterned metal layers, as well as a protective cover layer. Examples to consider include a two-layer stacked microstrip patch configuration or a slot-coupled patch with a microstrip feed network. Provide a detailed description of the process and its affect on antenna performance.
PHASE II: Demonstrate the process selected in Phase I by designing, fabricating and testing a small C-band, multi-layer, conformal array on a scale model of the leading edge of an aircraft wing. Model dimensions and antenna design parameters will be provided by the Air Force. Testing will include verification of the electrical and mechanical properties analyzed in Phase I, as well as complete testing of the antenna. If necessary, far field testing of the antenna can be completed using Air Force facilities.
DUAL USE COMMERCIALIZATION: Conformal array antennas have widespread potential for commercial application in mobile communications and information systems. Conformal array technology can easily be transferred to uses in commercial aircraft and automobiles, and to other DoD platforms such as tanks, ships, and armored personnel carriers.
REFERENCES: 1. W. Thomas, R.C. Hall, and D.I. Wu, "Effects of curvature on the fabrication of wraparound antennas", IEEE Antennas and Propagation Society International Symposium, Montreal, Canada, July 13-18, 1997, pp. 1512 - 1515.
2. D. Loffler, E. Gschwendtner, and W. Wiesbeck, "Design and Measurement of Conformal Antennas on Cylindrical and Spherical Geometries", 1999 IEEE Aficon 5th Africon Conference in Africa, Cape Town, South Africa, Sept 28-Oct 1, 1999, pp. 1005-1010.
3. Hansen, R.C., Ed., "Conformal antenna array design handbook", NTIS, AP-A110091, 1981.
KEYWORDS: microstrip antennas, conformal arrays, phased arrays, microwave substrates, airborne antennas, satellite communications
AF04-221 TITLE: Advanced High Frequency Tunable Filters for Wide-Band Arrays
TECHNOLOGY AREAS: Sensors, Electronics, Battlespace
OBJECTIVE: Develop filters capable of operating between 37 and 52 GHz, and tunable over 1 GHz bandwidth.
DESCRIPTION: As radar and communications continue to develop higher frequency applications, there is a clear need for having many channels operating in relatively narrow frequency bands. While large filter banks can accomplish this, such banks are difficult to deploy in space and are not ideal for air or ground based operation. What would help advance high frequency applications are affordable, tunable filters that allow for operation over a wide bandwidth. Filters based on thin film technology look most promising. A number of techniques have been tried to make thin film tunable filters including 1) changing the dielectric constant of the substrate material by using a ferroelectric, 2) making MEM?s switches to switch between filters, 3) altering the effective permittivity by physically moving tuning material with a piezoelectric, 4) making high temperature superconducting filters with selection switches, as well as combinations of these methods. Once developed, high frequency tunable filters will be a significant help in both phased array antennas, allowing them to be wide band, and digital beam forming, allowing control of both frequency and beam shape. Communication systems employing such frequency agile (tunable) antennas would become superior for use in a global satellite network, as they would be capable of covering many channels and rapidly switching channels thereby making for secure space-based communications. Tunable filters should also result in a lower noise level which would result in sensors and communication systems with greater dynamic ranges.
PHASE I: Include the following tasks:
1. Propose the design of at least two independent tunable filter designs. These must be electronically tunable and have a center frequency in the 37 to 52 GHz range.
2. Propose how the entire 37 to 52 GHz range can be covered with various designs of tunable filters.
3. Perform detailed modeling of the filter designs and calculate the loss at the center frequency and within the tunable range. Determine the bandwidth, or channels per GHz, that can operate within the tunable range.
4. Propose how in Phase II the losses can be reduced, the tunable range increased, and how the number of channels per GHz can be increased.
PHASE II: Demonstrate the ability of tunable filters and will include the following tasks:
1. Design filters which cover the frequency range of 37 to 52 GHz.
2. Design both the packaging and controls for the filters.
3. Build the filters, including their packaging and controls.
4. Test the filters. This will include measuring the actual bandwidth, the loss within the bandwidth, and channel width.
5. Deliver filters to AFRL/SNHA for testing and evaluation for Air Force and DoD applications.
DUAL USE COMMERCIALIZATION: While the main thrust of this work is high frequency and space-based communications, it should be easy to adapt high frequency tunable filter designs to lower frequencies. Such tunable filters would be competitive with existing filter banks that are used for commercial communications, such as cellular communications, where many channels must exist close to each other and channel cross talk must be minimize.
REFERENCES: 1. Moechly, B.H., Zhang, Y., "Strontium titanate Thin films for tunable YBa2Cu3O7 microwave filters," IEEE Transactions on Applied Superconductivity, 11, 450 (2001).
2. Yao, J Jason "RF MEMS from a device perspective," Journal of Micromechanics and Microengineering, 10, R9 (2000)
3. Lu, Jian et al. "RF tunable attenuator and modulator using high Tc superconducting filter," Electronic Letters, 35, 55 (1999).
4. Giannini, F., Limiti, E. Orengo, G. and Sanzi, P., "High-Q gyrator-based monolithic active tunable bandstop filter," IEE Proceedings ? Circuits, Devices and Systems. 145, 243 (1998).
5. Madden, J.M. "High temp superconductor RF devices," IEEE Potentials, 17, 17 (1998).
KEYWORDS: RF Filter, Tunable filter, Wide band, High frequency, W-band, Phased array antennas
AF04-222 TITLE: High Speed Optical Limiter for Laser Communications Systems
TECHNOLOGY AREAS: Sensors, Electronics, Battlespace
OBJECTIVE: Design/develop a high-speed optical limiter for protecting laser transmitters and receivers against laser attack.
DESCRIPTION: Optical limiters are nonlinear optical devices that limit the amount of power or energy transmitted. They function through either optically-induced nonlinear absorption or refraction or a combination of the two. At low incident optical power or pulse energy, the transmission of the system is high enough to allow nominal operation of the system. At high incident optical power or pulse energy, the transmission drops to protect sensitive components such as optical receivers or transmitters. Optical limiters have achieved fast turn-on, but high speed turn-off is limited by the recovery time of the medium which is often slow. The goal of this project is to develop a high speed optical limiter to protect optical receivers or transmitters on a laser-based space satellite communications system. Development of high power laser systems has reached the maturity that such systems are economically and technically feasible even for third world nations. Even scattered light from a nearby strike from such pulses may be energetic enough to damage highly sensitive optical transmitters and receivers. The optical limiter must protect against high energy laser pulses (nanosecond to femtosecond) and must support optical communication rates of > 100 Gbps with no more than one lost bit per pulse for laser threats from sources with pulses of < 5 psec duration. For threats from longer laser pulses, the response of the optical limiter system must follow the attacking laser pulse. The materials and systems used must be suitable for the space environment.
PHASE I: Activities in this phase include: designing an optical limiter with low insertion loss, capable of supporting telecom rates of > 40 Gbps for near infrared (800-1600 nm) laser communications systems and capable of protecting the system from laser attack by nanosecond to femtosecond laser pulses; determining requirements for operate-through and operate after modes; and determining the effects of the natural space radiation environment on optical limiter performance.
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