A printed broadband planar inverted-F antenna (PIFA) with zeroth-order resonator (ZOR) loaded is proposed whose shorting strip of the PIFA is replaced by an inter-digital capacitor and thin inductive strip in series. The loaded inter-digital capacitor and thin inductive strip act as a shorting strip at the 3.1 GHz, which allows the antenna to maintain its regular performance. Around 2.0 GHz, the antenna with the inter-digital capacitor and thin inductive strip works on the zeroth-order resonance mode, which makes the physical size be independent of the wavelength. By merging the two modes, a broadband performance can be achieved. The size of the antenna is only 12.5 mm×7.81 mm×1.6 mm with single layer. The measured antenna bandwidth is 1.63 GHz (about 65%), total gain is above 2.5 dBi and the simulated radiation efficiency is over 90% in the working band. Especially the antenna has same direction of the radiation patterns in the broadband. In the end, the antenna with lumped elements loading is also discussed.
2. Sanada, A., C. Caloz, and T. Itoh, "Planar distributed structures with negative refractive index," IEEE Trans. Microw. Theory Tech., Vol. 52, 1252-1263, 2004.
3. Sanada, A., C. Caloz, and T. Itoh, "Novel zeroth-order resonance in composite right/left-handed transmission line resonators," Proc. Asia-Pacic Microwave Conf., Vol. 3, 1588-1591, 2003.
4. Choi, J. and S. Lim, "Ultra-wideband power splitting/combining technique using zero-degree left-handed transmission lines," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 14-15, 2119-2127, 2010.
5. Sanada, A., M. Kimura, I. Awai, C. Caloz, and T. Itoh, "A planar zeroth-order resonator antenna using a left-handed transmission line," Proc. Eur. Microw. Conf., Vol. 3, 1341-1344, 2004.
6. Choi, J. and S. Lim, "Frequency and radiation pattern reconfigurable small metamaterial antenna using its extraordinary zeroth-order resonance," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 14-15, 2119-2127, 2008.
7. Dolatsha, N., M. Shahabadi, and R. Dehbashi, "Via-free cpw-based composite right/left-handed transmission line and a calibration approach to determine its propagation constant," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 11-12, 1599-1606, 2008.
8. Zhou, H., S. Qu, Z. Pei, Y. Yang, J. Zhang, J. Wang, H. Ma, C. Gu, X. Wang, Z. Xu, W. Peng, and P. Bai, "A high-directive patch antenna based on all-dielectric near-zero-index metamaterial superstrates," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 10, 1387-1396, 2010.
9. Yu, A., F. Yang, and A. Elsherbeni, "A dual band circularly polarized ring antenna based on composite right and left handed metamaterials," Progress In Electromagnetics Research, Vol. 78, 73-81, 2008.
10. Si, L.-M. and X. Lv, "CPW-fed multi-band omni-directional planar microstrip antenna using composite metamaterial resonators for wireless communications," Progress In Electromagnetics Research, Vol. 83, 133-146, 2008.
11. Antoniades, M. A. and G. V. Eleftheriades, "A broadband dual-mode monopole antenna using NRI-TL metamaterial loading," IEEE Antennas Wireless Propag. Lett., Vol. 8, 258-261, 2009.
12. Zhu, J., M. A. Antoniades, and G. V. Eleftheriades, "A compact tri-band monopole antenna with single-cell metamaterial loading," IEEE Trans. Antennas Propag., Vol. 58, No. 4, 1031-1038, 2010.
13. Deng, S. M., C. L.Tsai, C. K. Yeh, S. S, and Bor, "CPW-fed PIFAS with a capacitively coupling slot for dual wide-band operations," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 5-6, 721-733, 2010.
14. Sanchez-Montero, R., S. Salcedo-Sanzand, J. A. Portilla-Figueras, and R. Langley, "Hybrid pifa-patch antenna optimized by evolutionary programming," Progress In Electromagnetics Research, Vol. 108, 221-234, 2010.
15. Yang, C. W. and C. W. Jung, "Broad dual-band PIFA using self-complementary structure for DVB-H applications," Electron. Lett., Vol. 46, No. 4, 606-608, 2010.
16. Sim, D.-U. and J.-I. Choi, "A compact wideband modified planar inverted F antenna (PIFA) for 2.4/5-GHz WLAN applications," IEEE Antennas and Wireless Propag. Lett., Vol. 5, No. 1, 391-394, 2006.
17. Park, J.-H., Y.-H. Ryu, J.-G. Lee, and J.-H. Lee, "Epsilon negative zeroth-order resonator antenna," IEEE Trans. Antennas Propag., Vol. 55, No. 12, 3710-3712, 2007.
18. Huang, J.-Q. and Q.-X. Chu, "Small ZOR antenna with high efficiency based on epsilon negative transmission line," Proc. of Int. Conf. on Microwave & Millimeter Wave Tech., 528-531, 2010.
19. Bahl, I., Lumped Elements for RF and Microwave Circuits, Artech House, Norwood, 2003.