Dipole antennas on a substrate without a ground plane are common in wireless sensor networks and RFID applications. This paper reviews a number of theoretical approaches to solving for the effective permittivity when the substrate material is thin. The surface impedance and slab waveguide propagation techniques are compared to a capacitive solution and an insulated wire antenna. The insulated wire method gives most accurate results (< 3.5%) and was verified using numerical modeling and experimental work. Measurements on a planar straight dipole on FR4 (fc = 1.50 GHz) compare favorably with the antenna modelled without the substrate and scaled using the insulated wire technique at (fc = 1.49 GHz). The method can be readily incorporate the effect of an RFID antenna on a thin plastic film placed on a wide variety of lossy and lossless objects.
David V. Thiel,
"A Robust Method of Calculating the Effective Length of a Conductive Strip on an Ungrounded Dielectric Substrate," Progress In Electromagnetics Research M,
Vol. 35, 57-66, 2014. doi:10.2528/PIERM13122404
1. Finkenzeller, D. K., RFID Handbook: Radio-frequency Identification Fundamentals and Applications, 2nd Ed., J. Wiley & Sons, New York, 2003.
2. Kanesan, M., D. V. Thiel, A. Galehdar, and S. G. O'Keefe, "Rapid analysis and optimization of planar Yagi-Uda dipole arrays printed on a dielectric substrate," Int. J. RF Microwave Comput.-Aided Eng., 2013, Doi: 10.1002/mmce.20747.
3. Abbosh, A., "Accurate effective permittivity calculation of printed center-fed dipoles and its application to quasi Yagi-Uda antennas," IEEE Trans. Antennas Propag., Vol. 61, No. 4, 2297-2300, 2013. doi:10.1109/TAP.2012.2231925
4. Kanesan, M., D. V. Thiel, and S. G. O'Keefe, "The effect of lossy dielectric objects on a UHF RFID meander line antenna," IEEE AP-S International Symposium, 1-2, Chicago, Jul. 2012.
5. Jackson, D. and N. Alexopoulos, "Analysis of planar strip geometries in a substrate-superstrate configuration," IEEE Trans. Antennas Propag., Vol. 34, No. 12, 1430-1438, 1986. doi:10.1109/TAP.1986.1143784
6. Delgado, H. J. and M. H. Thursby, "A novel neural network combined with FDTD for the synthesis of a printed dipole antenna," IEEE Trans. Antennas Propag., Vol. 53, No. 7, 2231-2236, 2005. doi:10.1109/TAP.2005.850706
7. Zhang, Y., Z. N. Chen, and M. Y. W. Chia, "Characteristics of planar dipoles printed on finite-size PCBs in UWB radio systems," IEEE AP-S International Symposium, Vol. 3, 2512-2515, Monterey, Jun. 2004.
8. Arima, T., T. Uno, and M. Takahashi, "FDTD analysis of printed antenna on thin dielectric sheet including quasi-static approximation," IEEE AP-S International Symposium, Vol. 1, 1022-1025, Monterey, Jun. 2004.