This paper investigates a miniaturized resonant antenna that comprises a meandered monopole and a partial ground plane. A bandwidth enhancement is found using the ground plane on the back side of the circuit board where the entire communication system resides. The meandered monopole together with the ground plane forms a wideband dipole antenna. The design shows over 25% 10 dB impedance bandwidth at 2.5 GHz ISM band with a monopole area of 300 mils by 166 mils on a small circuit board and a backside ground plane 1500 mils by 600 mils. The wire length is about one third and the Q factor is about twice as compared against the case of using a straight quarter-wave microstrip monopole. The antenna Q factor as a function ground plane area is characterized. The use of circuit ground as a part of an antenna should find useful applications in portable wireless systems. Good agreements are found between simulated and measured antenna gain patterns and return loss.
2. Garg, R., Microstrip Antenna Design Handbook, Artech House, 2001.
3. Soras, C., M. Karaboikis, G. Tsachtsiris, and V. Makios, "Analysis and design of an inverted-F antenna printed on a PCMCIA card for the 2.4 GHz ISM band," IEEE Antennas and Propagation Magazine, Vol. 44, No. 1, 37-44, February 2002.
4. Sutono, A., D. Heo, Y.-J. Chen, and J. Laskar, "High-Q LTCC-based passive library for wireless system-on-package (SOP) module development ," IEEE Transaction on Microwave Theory and Techniques, Vol. 49, No. 10, 1715-1724, October 2001.
5. Sawicki, A. and K. Sachse, "Novel coupled-line conductor-backed coplanar and microstrip directional couplers for PCB and LTCC applications," IEEE Transaction on Microwave Theory and Techniques, Vol. 51, No. 6, 1743-1751, June 2003.
6. Lai, A., T. Itoh, and C. Caloz, "Composite right/left-handed transmission line metamaterials," IEEE Microwave Magazine, Vol. 5, No. 3, 34-50, September 2004.
7. Eleftheriades, G. V., A. K. Iyer, and P. C. Kremer, "Planar negative refractive index media using periodically L-C loaded transmission lines ," IEEE Trans. Microwave Theory Tech., Vol. 50, No. 12, 2702-2712, Dec. 2002.
8. Best, S. R., "A discussion on the quality factor of impedance matched electrically small wire antennas," IEEE Transaction on Antennas and Propagation, Vol. 53, No. 1, 502-508, January 2005.
9. Stuar, H. R., S R. Best, and A. D.Yaghjian, "Limitations in relating quality factor to bandwidth in a double resonance small antenna," IEEE Ant. Wireless Prop. Lett., Vol. 6, 460-463, 2007.
10. Kwon, D.-H., "On the radiation Q and the gain of crossed electric and magnetic dipole moments," IEEE Transaction on Antennas and Propagation, Vol. 53, No. 5, 1681-1687, May 2005.
11. Warnagiris, T. J. and T. J. Minardo, "Performance of a meandered line as an electrically small transmitting antenna," IEEE Transaction on Antennas and Propagation, Vol. 46, No. 12, 1797-2801, December 1998.
12. Jung, J. and Y. Lim, "A Broadband meander line monopole antenna," Microwave Journal, Vol. 50, No. 10, 154-168, October 2007.
13. Zhang, Y. and H. Y. D. Yang, "Ultra slow-wave periodic transmission line using 3D substrate metallization," IEEE MTT-S International Microwave Symposium, 891-894, Atlanta, June 2008.
14. Yaghjian, A. D. and S. R. Best, "Impedance, bandwidth, and Q of antennas," IEEE Transaction on Antennas and Propagation, Vol. 53, No. 4, 1298-1323, April 2005.