This work describes the fabrication and characterization of a frequency reconfigurable patch antenna using ferrofluid actuation. The reconfiguration is based on a variation of dielectric constant of the substrate. For this, the substrate is modified by placing channels in it filled with ferrofluid and isopropanol-water solution. The relative position of ferrofluid along the channels is controlled by an external magnetic field which results in a relocatable spatial difference in the dielectric constant value. The targeted reconfigurability with stable radiation characteristics at the accessible frequencies is validated through antenna reflection loss and radiation pattern measurements. Additionally, actuation speed of the fluid immerged in the polar mixture is measured by sequential image analysis.
2. Christodoulou, C. G., Y. Tawk, S. A. Lane, and S. R. Erwin, "Reconfigurable antennas for wireless and space applications," Proceedings of the IEEE, Vol. 100, 2250-2261, 2012.
3. Yang, S., C. Zhang, H. K. Pan, A. E. Fathy, and V. K. Nair, "Frequency-reconfigurable antennas for multiradio wireless platforms," IEEE Microwave Magazine, Vol. 10, 66-83, 2009.
4. Bhattacharjee, T., H. Jiang, and N. Behdad, "A fluidically tunable, dual-band patch antenna with closely spaced bands of operation," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 118-121, 2016.
5. Murray, C. and R. R. Franklin, "Independently tunable annular slot antenna resonant frequencies using fluids," IEEE Antennas and Wireless Propagation Letters, Vol. 13, 1449-1452, 2014.
6. Huff, G. H., D. L. Rolando, P. Walters, and J. McDonald, "A frequency reconfigurable dielectric resonator antenna using colloidal dispersions," IEEE Antennas and Wireless Propagation Letters, Vol. 9, 288-290, 2010.
7. Dey, A. and G. Mumcu, "Microfluidically controlled frequency-tunable monopole antenna for high-power applications," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 226-229, 2016.
8. Kim, D., R. G. Pierce, R. Henderson, S. J. Doo, K. Yoo, and J.-B. Lee, "Liquid metal actuation-based reversible frequency tunable monopole antenna," Applied Physics Letters, Vol. 105, 234104, 2014.
9. Wang, M., C. Trlica, M. R. Khan, M. D. Dickey, and J. J. Adams, "A reconfigurable liquid metal antenna driven by electrochemically controlled capillarity," Journal of Applied Physics, Vol. 117, 194901, 2015.
10. Morales, D., Morales, N. A. Stoute, Z. Yu, D. E. Aspnes, and M. D. Dickey, "Liquid gallium and the eutectic gallium indium (EGaIn) alloy: Dielectric functions from 1.24 to 3.1 eV by electrochemical reduction of surface oxides," Applied Physics Letters, Vol. 109, 091905, 2016.
11. Khan, M. R., G. J. Hayes, J.-H. So, G. Lazzi, and M. D. Dickey, "A frequency shifting liquid metal antenna with pressure responsiveness," Applied Physics Letters, Vol. 99, 013501, 2011.
12. King, A. J., J. F. Patrick, N. R. Sottos, S. R. White, G. H. Huff, and J. T. Bernhard, "Microfluidically switched frequency-reconfigurable slot antennas," IEEE Antennas and Wireless Propagation Letters, Vol. 12, 828-831, 2013.
13. Morishita, A. M., C. K. Y. Kitamura, A. T. Ohta, and W. A. Shiroma, "A liquid-metal monopole array with tunable frequency, gain, and beam steering," IEEE Antennas and Wireless Propagation Letters, Vol. 12, 1388-1391, 2013.
14. Rodrigo, D., L. Jofre, and B. A. Cetiner, "Circular beam-steering reconfigurable antenna with liquid metal parasitics," IEEE Transactions on Antennas and Propagation, Vol. 60, 1796-1802, 2012.
15. Balanis, C. A., Antenna Theory: Analysis and Design, 3rd edition (With CD), Wiley India Pvt. Limited, 2009.
16. Garg, R., Microstrip Antenna Design Handbook, Artech House, 2001.
17. Devi, M. and D. Mohanta, "Rheological properties of iron oxide based ferrofluids," AIP Conference Proceedings, Vol. 1147, 495-501, 2009.
18. Furumura, K. and S. Matsunaga, "Process for producing a ferrofluid, and a composition thereof,", ed: Google Patents, 1984.