N092-116 TITLE: Efficient Broadband Electrically Small Antenna Arrays

TECHNOLOGY AREAS: Air Platform, Sensors, Electronics, Battlespace

ACQUISITION PROGRAM: PMA-274, Presidential Helicopter; PMA-290; PMA-231

OBJECTIVE: Develop new technologies to optimize the design electrically small, broadband antenna arrays for communication, electronic support and radar systems

DESCRIPTION: Using electrically small tuned antennas can be advantageous as they can be placed in close proximity of each other saving real estate and, making it possible to deploy phased arrays on small footprints. These small arrays are a very attractive option to traditional arrays made of resonant elements for communication, electronic support and radar systems on air platforms and ground/sea vehicles. The greatest impediment to widespread usage of such arrays is the low efficiency and narrowband impedance matching limitations. Currently these limitations are partially compensated for by increased transmitter power and/or improved receiver amplifier performance.

The critical elements to be investigated are individual broadband (multiple octave) radiator design, optimal integration into an array where strong mutual coupling is present, and intelligent impedance matching to ensure the delivery of maximum power between the radiator and the transceiver, helping to improve the overall efficiency of the array. The performance of these arrays as installed on the hosting platform is critical. Accurate three-dimensional, full-wave, time-domain, integral equation electromagnetic simulation methods will be critical for the design of broadband elements, array architecture and impedance characterization and optimization.

PHASE I: Develop a time domain analysis and design technique using associated Laguerre polynomials for arbitrary shaped conducting structures. Merge the structure generation with an interface to perform initially with triangular patch models. Develop post processing for the plot of near and far fields and network parameters in frequency domain.

PHASE II: Extend the methodology to deal with quadrilateral patches so that both the frequency and the time domain techniques could use the same discretization. Modify the code for the solution in a parallel environment. Incorporate the effect of loading in this methodology. Demonstrate the developed prototype technology.

PHASE III: Further extend the methodology for a cluster environment for the solution of composite conducting and dielectric bodies with frequency dependent material parameters and analysis of nonlinearly loaded structures. Transition the technology to the fleet.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Efficient electrically-small broadband arrays could be deployed on a large variety of military land, sea and air platforms to provide an attractive alternative for communication, electronic support and radar systems. In civilian applications, it could be used for small footprint mobile communications systems.

REFERENCES:
1. J. de Mingo et al, "An RF electronically controlled impedance tuning network design and its application to an antenna input impedance automatic matching system," IEEE Trans. Microwave Theory & Tech., Vol. 52 No. 2, pp. 489 � 497, Feb. 2004

2. H. Wheeler, "Fundamental limitations of small antennas," Proceedings of IRE, Vol. 35 No. 12, pp. 1479 � 1484, Dec. 1947.

3. L. Chu, "Physical limitations of omni-directional antennas," Journal of Applied Physics, Vol. 19, pp. 1163 � 1175, Dec. 1948.

4. Mengtao Yuan, et al., "Conditions for generation of stable and accurate hybrid TD-FD MoM solutions," Microwave Theory and Techniques, IEEE Transactions on Volume 54, Issue 6, Part 1, June 2006 Page(s):2552 - 2563.

KEYWORDS: Antenna; Electrically Small Antenna Arrays; Time-Domain Integral Equation; Broadband Arrays; Antenna Impedance Matching; hybrid method

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