An array of conformal antenna structures mounted on a bending surface exhibits a substantial shift in main beam direction. This paper demonstrates a method to compensate for the induced beam shift by using the change in length of the surface produced by the bend. This change in length modifies the capacitance in a composite right/left-handed transmission (CRLHTL) line, causing a phase shift in the line. A potential implementation is proposed that can correct an 18º beam shift with only an induced change in length of 0.144%. The paper establishes that this passive compensation concept is feasible and provides significant benefits over active compensation systems in terms of weight reduction, cost, simplification and the ability to operate in radio silence.
1. Lockyer, A. J., J. N. Kudva, D. M. Kane, B. P. Hill, C. A. Martin, A. C. Goetz, and J. Tuss, "A qualitative assessment of smart skins and avionic/structures integration," SPIE Conference on Smart Structures and Materials, Vol. 2189, 172-183, Orlando, Florida, USA, Feb. 14, 1994.
2. Lockyer, A. J., K. H. Alt, D. P. Coughlin, M. D. Durham, J. N. Kudva, A. C. Goetz, and J. Tuss, "Design and development of a conformal load-bearing smart-skin antenna: Overview of the AFRL smart skin structures technology demonstration (S3TD) program," SPIE Conference on Smart Structures and Materials, Vol. 3674, 410-424, Newport Beach, California, USA, Mar. 1999.
3. Callus, P. J., "Conformal load bearing antenna structure for Australian defence force aircraft,", DSTO Technical Report, 40, DSTO-TR-1963, Mar. 2007, http://hdl.handle.net/1947/8164.
4. Smallwood, B. P., R. A. Canfield, and A. J. Terzuoli, Jr., Structurally Integrated Antennas on a Joined-wing Aircraft, Vol. 1, 549-556, Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 2003.
5. Seidel, T. J., W. S. T. Rowe, and K. Ghorbani, "Passive compensation of beam shift in an array on a bending surface," 2011 European Radar Conference (EuRAD), Vol. 85, No. 88, Manchester, .
6. Banks, D., M. Berden, B. Baron, and J. Tenbarge, "Structurally integrated X-band array development," Multifunctional Structures/Integration of Sensors and Antennas, 17-1-17-12, 2006.
7. Santori, A., J. Barrµere, G. Chabriel, C. Jauffret, and D. Medynski, "Array shape self-calibration for large flexible antenna," IEEE Aerospace Conference Proceedings, No. 4161477, 2007.
8. Caloz, C. and T. Itoh, "Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications, the Engineering Approach ," John Wiley & Sons, New York, 2006, ISBN-10: 0-471-66985-7.
9. Damm, C., M. Schussler, M. Oertel, and R. Jakoby, "Compact tunable periodically LC loaded microstrip line for phase shifting applications," IEEE MTT-S International Microwave Symposium, Vol. 1-4, 2003-2006, Long Beach, CA, Jun. 2005.
10. Sheng, S., P. Wang, and C. K. Ong, "Compact tunable periodically LC loaded phase shifter using left-handed transmission line," Microwave and Optical Technology Letters, Vol. 51, No. 9, 2127-2129, 2009. doi:10.1002/mop.24544
11. Hongjoon, K., S.-J. Ho, M.-K. Choi, A. B. Kozyrev, and D. W. van der Weide, "Combined left- and right-handed tunable transmission lines with tunable passband and 0 phase shift," IEEE Transactions on Microwave Theory and Techniques, Vol. 54, No. 12, 4178-4184, Dec. 2006. doi:10.1109/TMTT.2006.885884
12. Bahl, I., Lumped Elements for RF and Microwave Circuits, Artech House Microwave Library, Norwood, MA, 2003, ISBN 1-58053-309-4.