1. Mutual Coupling Between Coax-fed Rectangular Microstrip Antennas Embedded in Layered Uniaxial Anisotropic Dielectrics Benjamin D. Braaten* Dimitrios E. Anagnostou Keith W. Whites 1 2 2 1. North Dakota State University, Department of Electrical and Computer Engineering, Fargo, North Dakota. 2. South Dakota School of Mines and Technology, Department of Electrical and Computer Engineering, Rapid City, South Dakota.

2. Topics  Problem Definition  Interests and Background  Mutual Coupling Results  Single anisotropic substrate  Single anisotropic superstrate  Separated by an anisotropic layer  Discussion/Conclusion North Dakota State University

3. Problem Definition Consider: North Dakota State University Optical axis is in the y- direction.

4. Interests and Background North Dakota State University The previous problem is of interest in many fields.  Microstrip antenna arrays [1].  Frequency Selective Structures (FSS) [2].  Radio Frequency Identification (RFID) [3].  IC based antennas.  “Engineered Materials” [4]. [1] David M. Pozar and Daniel H. Schaubert, “Microstrip Antennas: The analysis and Design of Microstrip Antennas and Arrays”, IEEE Press, Piscataway, NJ, 1995. [2] A.L.P.S. Campos an A.G. d'Assuncao, “Scattering parameters of a frequency selective surface between anisotropic dielectric layers for incident co-polarized plane waves,” IEEE Antennas and Propagation Society International Symposium, 2001, Vol. 4, July 8-13, 2001, p. 382-385. [3] K. Finkenzeller, RFID Handbook:Fundamentals and Applications in Contactless Smart Cards and Identification, John Wiley and Sons, West Sussex, England, 2003. [4] E. A. Navarro, A. Luximon, I. J. Craddock, D. L. Paul and M. Dean, “Multilayer and conformal antennas using synthetic dielectric substrates,” IEEE Antennas and Propagation, Vol. 51, No. 4, pp. 905-908, 2003.

5. Microstrip Patch Results North Dakota State University Consider: L = 6.55 cm, W = 10.57 cm, d 1 = d 2 = 1.58 cm f = 1.41 GHz.

6. Microstrip Patch Results North Dakota State University x d = 16.8 mm z d = 52.85 mm f = 1.41 GHz Permittivity = 4.25 (chosen by isolating the patch)

7. Microstrip Patch Results North Dakota State University A single grounded anisotropicsubstrate (d 1 = 1.58 mm and d 2 = 0 mm.): (Pozar) David M. Pozar and Daniel H. Schaubert, “Microstrip Antennas: The analysis and Design of Microstrip Antennas and Arrays”, IEEE Press, Piscataway, NJ, 1995.

8. Microstrip Patch Results North Dakota State University A single grounded anisotropicsubstrate (d 1 = 1.58 mm and d 2 = 0 mm.):

9. Microstrip Patch Results North Dakota State University A single anisotropiccover (d 1 = 1.58 mm d 2 = 1.58 mm d 2 = 1.58 mm permittivity = 4.25):

10. Microstrip Patch Results North Dakota State University A single anisotropiccover (d 1 = 1.58 mm d 2 = 1.58 mm d 2 = 1.58 mm permittivity = 4.25):

11. Microstrip Patch Results North Dakota State University Separated by a single anisotropic layer (d 1 = 1.58 mm d 2 = 1.58 mm d 2 = 1.58 mm permittivity = 4.25):

12. Microstrip Patch Results North Dakota State University Separated by a single anisotropic layer (d 1 = 1.58 mm d 2 = 1.58 mm d 2 = 1.58 mm permittivity = 4.25):

13. Conclusion North Dakota State University  The coupling between two rectangular microstrip patch antennas in layered anisotropic dielectrics was investigated.  Initially, the E- and H-plane coupling between two microstrip antennas on a single anisotropic substrate was investigated.  It is shown that the permittivity in the y-direction (direction of the optical axis) has the largest impact on the mutual coupling in BOTH the E- and H-planes.  An increase in the permittivity of the substrate in the direction of the optical axis reduces the traditionally stronger E-plane coupling while increasing the traditionally weaker H-plane coupling.

14. Conclusion North Dakota State University  Next, the E- and H-plane coupling between two microstrip antennas with a single anisotropic superstrate was investigated.  It is shown that the mutual coupling is slightly reduced in both the E- and H-planes by an increase in permittivity in both directions of the superstrate (i.e., in the direction of the optical axis and in the direction orthogonal to the optical axis).  Finally, the two microstrip antennas were separated by a single anisotropic superstrate and the coupling was investigated.  It is shown that both components of the permittivity affect the mutual coupling in both the E- and H-planes.

15. Questions Thank you for listening! North Dakota State University