SBIR-STTR Award

A unique and beneficial configuration for a multiple input omni- directional microwave antenna is described, in which a circular phased array of eight antenna elements is fed by an eight input butler network. Proper design of the array geometry and network will allow up to seven transmitters to share the same antenna simultaneously without interference, each transmitter producing an omni-directional radiation pattern. The transmitters are isolated from one another by the butler network. A Phase I study is proposed to investigate the critical design aspects of the configuration through analysis, computer modeling and laboratory experiment. Phase I would result in the complete conceptual design of the multiple input antenna. Critical aspects of the design will be verified through testing in the laboratory, thereby providing the feasibility of the concept and eliminating the risk for further development in Phase II

Current robotic ground vehicles transmit four simultaneous microwave frequency video channels back to a command and control center. Because there is little available room, use of separate antennas for each transmitter is not feasible and frequency multiplexers have unacceptably high losses because of the small channel separations used. This Phase II proposal is for the development of an omnidirectional antenna array fed by a Butler matrix, which allows the array to be "reused" by each transmitter. Up to seven transmitters operating in the 1.71-1.85 and 2.2-2.3 GHz telemetry bands can simultaneously be connected to this antenna without interference. This novel approach will improve system performance and versatility through elimination of the lossy and frequency specific multiplexers presently in use. Six prototype antennas plus an environmental test article are to be produced in the Phase II effort. The design will be thoroughly evaluated in the laboratory and in the field while mounted on a robotic vehicle. The feasibility of this concept was proven in a Phase I effort through the design, construction and evaluation of an engineering test model. This proposal includes an option for conversion of the array to a single input steered directional antenna.