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Affordable Sub-array for TT & C Phased Array Antennas


OBJECTIVE: Design, develop, and demonstrate the feasibility of a low-cost subarray architecture for large communication phased array antennas used to support space satellite operations. DESCRIPTION: Phased array antennas have demonstrated the high performance in throughput, responsiveness, flexible operability and lower maintenance cost required for Air Force communication and surveillance mission operational support. However the acquisition cost of active phased array antennas is the single most significant factor hindering their wide application in both military and commercial fields. For example, cost is a major impediment to the realization of a large hemispherical phased array antenna useful for horizon-to-horizon simultaneous coverage of multi-satellite TT & C systems such as that employed by the Air Force Satellite Control Network. The cost of the transmit/receive (T/R) modules, subarray, and associated control electronics may constitute over half of the total antenna cost [1, 2] While efforts are currently underway to reduce the cost of the T/R module to less than $100 per unit, efforts to reduce the cost of the subarray (radiating elements, RF beam former, DC and control distribution, T/R module retention, structure, etc.) still need to be undertaken to reduce costs that are currently on the order of $140 per radiating element. The objective of this solicitation is to design, develop, and demonstrate the feasibility of very low-cost (below $100 per element in high volume production) subarray concepts for large communication phased array antennas through innovation of cost-effective element design, interconnect and architecture, and material technologies. The antenna subarray developed under this effort should provide equivalent performance to the current state-of-the-art L- and S-band subarray developed under the Geodesic Dome Phased Array Antenna (GDPAA) program [1,5]. This design consists of a multi-layer printed circuit board radiating element aperture and network, as well as the control, interface and support structures. Likewise, the new subarray must include these components and be able to support simultaneous transmit and receive with high isolation (>45 dB), full-duplex multiple beams (at least one transmit and two receive beams from a single subarray), 120 degree field-of-view, and high gain over noise temperature from a single operating phased array antenna. The subarray shall be capable of interfacing T/R modules with array elements. The latest T/R module form factor will be provided by the government at the start of Phase I, but alternatives to this interface should be part of the Phase I study. Real-time replacement of T/R modules to support hot maintenance requirements is desired, but alternatives to this approach could be considered if they provide significant cost savings. The Phase I effort shall identify innovative low cost radiating element and RF/DC architectures and assess technical issues associated with specific architectures and fabrication approaches. Candidate design concepts shall be assessed in terms of their performance (amplitude and phase errors, frequency bandwidth, isolation, loss, power handling, etc.), feasibility, manufacturability, reliability and cost. The effort shall document and rank subarray candidates for Phase II development. In Phase II a candidate subarray design will be selected based on numerical simulations and trade-off studies of performance, manufacturability, reliability, cost, adaptability, etc. A complete prototype subarray assembly will be fabricated and tested and the subarray measured values will be compared with simulated results. The Phase II effort shall also identify efficient manufacturing, test and quality control processes for large quantity production, perform realistic production cost and timeline analysis, and assess the feasibility and cost of integrating the antenna subarray into a large phased array antenna for space mission support. PHASE I: Phase I activity shall include: (1) develop subarray performance requirements for supporting satellite operations; (2) develop subarray architecture concepts to support those requirements; (3) identify technical issues for selected architectures/fabrication approaches; (4) assess candidate designs in terms of performance, cost, etc; and (5) document subarray candidates for Phase II development. PHASE II: Based on the Phase I results, the contractor shall: (1) select the most promising subarray design by performing numerical simulations and refining trade-offs on performance, manufacturability, reliability, cost, adaptability, etc.; (2) fabricate a prototype subarray antenna assembly of a size and format to be negotiated between the Contractor and the Government; (3) test the subarray and compare with simulations; (4) perform realistic cost analysis including production and integration costs. PHASE III: The antenna subarray can be used to reduce the cost of large phased array antennas for satellite communication and space control. The antenna subarray is equally applicable to commercial satellite control operations. REFERENCES: 1. Henderson, M.,"GDPAA Advanced Technology Demonstration Overview and Results,"2010 IEEE International Symposium on Phased Array Systems & Technology, 12-15 Oct. 2010, Boston, MA. 2. Liu, S. F., Survey of Phased Array Antenna for AFSCN Application, May 1998. 3. Tomasic, B., Analysis and Design Trade-Offs of Candidate Phased Array Architectures for AFSCN Application, Presentation to the Second AFSCN Phased Array Antenna Workshop, Hanscom AFB, April 1998. 4. Mailloux, R. J., Phased Array Antenna Handbook, Artech House, 1994. 5. Sarjit Bharj, Boris Tomasic, Gary Scalzi, John Turtle and Shiang Liu,"A Full-Duplex, Multi-Channel Transmit/Receive Module for an S-Band Satellite Communications Phased Array", IEEE 2010 International Symposium on Phased Array Systems and Technology, 14-18 October 2010.
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