The feasibility of using a capacitive sensor to sense the proximity of an external load, especially a finger, to a mobile terminal antenna was experimentally studied using a PIFA-type antenna as one of the sensor's electrodes. It was found that with the proposed arrangement it is possible to detect objects with permittivity close to that of body tissue or the conductivity level of aluminium and the size of a human finger at distances up to 15 mm.
2. Krogerus, J., J. Toivanen, C. Icheln, and P. Vainikainen, "Effect of the human body on total radiated power and the 3-D radiation pattern of mobile handsets," IEEE Trans. Instrumentation and Measurement, Vol. 56, No. 6, 2375-2385, December 2007.
doi:10.1109/TIM.2007.903591
3. Pelosi, M., O. Franek, M. Knudsen, M. Christensen, and G. Pedersen, "A grip study for talk and data modes in mobile phones," IEEE Trans. Antennas and Propag., Vol. 57, No. 4, 856-865, April 2009.
doi:10.1109/TAP.2009.2014590
4. Lindberg, P., A. Kaikkonen, and B. Kochali, "Body loss measurements of internal terminal antennas in talk position using real human operator," Proc. Int. Workshop on Antenna Tech.: Small Antennas and Novel Metamaterials, IWAT 2008, 358-361, Chiba, Japan, March 2008.
doi:10.1109/IWAT.2008.4511354
5. Ramachandran, P., Z. Milosavljevic, and C. Beckman, Adaptive matching circuitry for compensation of finger effect on handset antennas, Proc. 3rd European Conference on Antennas and Propag. EuCAP 2009, 801-804.
6. Gabriel, S., R. W. Lau, and C. Gabriel, "The dielectric properties of a human body tissues: III. Parametric models for the dielectric spectrum of tissues ," Phys. Med. Biol., Vol. 41, 2271-2293, 1996.
doi:10.1088/0031-9155/41/11/003
7. Riddle, B., J. Baker-Jarvis, and J. Krupka, "Complex permittivity measurements of common plastics over variable temperature," IEEE Trans. Microwave Theory and Tech., Vol. 51, No. 3, 727-733, March 2003.
doi:10.1109/TMTT.2003.808730
8. Myllymaki, S., A. Huttunen, M. Berg, M. Komulainen, and H. Jantunen, "Method for measuring user-induced load on mobile terminal antenna," IET Electronics Letters, Vol. 45, No. 21, 1065-1066, October 8, 2009.
doi:10.1049/el.2009.1728
9. Komulainen, M., M. Berg, H. Jantunen, E. Salonen, and C. Free, "A frequency tuning method for a planar inverted-F antenna," IEEE Trans. Antennas and Propag., Vol. 56, No. 4, 944-950, April 2008.
doi:10.1109/TAP.2008.919200
Submit
