volume | PIER Journals

Abstract

A compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna with a small size of 22×36 mm² is proposed for portable devices. The MIMO antenna consists of two symmetric slot antenna elements with back-to-back separation of 7 mm. Adjusting the open-ended stepped radiator and position of the microstrip line can realize UWB impedance matching. In order to achieve wideband and high isolation, a cross-shaped decoupling slot and connecting metal line are etched on the ground plane. The cross-shaped slot between the antenna elements is used to decrease the mutual coupling caused by near-field at middle and high bands. The connecting line can be interpreted as a neutralized line, which produces an additional current path for the coupling ground currents. Measured S-parameters show that the isolation is better than -16 dB across the UWB of 3.1-10.6 GHz. The radiation pattern, gain, and envelope correlation coefficient are also measured. The proposed antenna with a simple structure and compact size achieves good impedance matching and excellent port isolation simultaneously, and is a good candidate for UWB MIMO systems.

1. Roy, S., J. R. Foerster, V. S. Somayazulu, and D. G. Leeper, "Ultrawideband radio design: The promise of high-speed, short-range wireless connectivity," Proceedings of the IEEE, Vol. 92, No. 2, 295-311, Feb. 2004.
doi:10.1109/JPROC.2003.821910

2. Wallace, J., M. Jensen, A. Swindlehurst, and B. Jeffs, "Experimental characterization of the MIMO wireless channel: Data acquisition and analysis," IEEE Trans. Wireless Commun., Vol. 2, No. 2, 335-343, Mar. 2003.
doi:10.1109/TWC.2003.808975

3. Wu, C.-H., G.-T. Zhou, Y.-L.Wu, and T.-G. Ma, "Stub-loaded reactive decoupling network for twoelement array using even-odd analysis," IEEE Antennas Wireless Propag. Lett., Vol. 12, 452-455, 2013.
doi:10.1109/LAWP.2013.2255255

4. Wang, Y. and Z. W. Du, "A wideband printed dual-antenna with three neutralization lines for mobile terminals," IEEE Trans. Antennas Propag., Vol. 62, No. 3, 1495-1500, Mar. 2014.
doi:10.1109/TAP.2013.2295226

5. See, T. S. P. and Z. N. Chen, "An ultrawideband diversity antenna," IEEE Trans. Antennas Propag., Vol. 57, No. 6, 1597-1605, Jun. 2009.
doi:10.1109/TAP.2009.2019908

6. Najam, A. I., Y. Duroc, and S. Tedjni, "UWB-MIMO antenna with novel stub structure," Progress In Electromagnetics Research C, Vol. 19, 245-257, 2011.

7. Zhang, S., Z. Ying, J. Xiong, and S. He, "Ultrawideband MIMO/diversity antennas with a tree-like structure to enhance wideband isolation," IEEE Antennas Wireless Propag. Lett., Vol. 8, 1279-1282, 2009.
doi:10.1109/LAWP.2009.2037027

8. Zhang, S., B. K. Lau, A. Sunesson, and S. He, "Closely-packed UWB MIMO/diversity antenna with different patterns and polarizations for USB dongle applications," IEEE Trans. Antennas Propag., Vol. 60, No. 9, 4372-4380, 2012.
doi:10.1109/TAP.2012.2207049

9. Jusoh, M., M. F. B. Jamlos, M. R. Kamarudin, and M. F. B. A. Malek, "A MIMO antenna design challenges for UWB application," Progress In Electromagnetics Research B, Vol. 36, 357-371, 2012.
doi:10.2528/PIERB11092701

10. Qin, H. and Y.-F. Liu, "Compact UWB MIMO antenna with ACS-fed structure," Progress In Electromagnetics Research C, Vol. 50, 29-37, 2014.
doi:10.2528/PIERC14033105

11. Liu, L., S. W. Cheung, and T. I. Yuk, "Compact MIMO antenna for portable devices in UWB applications," IEEE Trans. Antennas Propag., Vol. 61, No. 8, 4257-4264, Aug. 2013.
doi:10.1109/TAP.2013.2263277

12. Dissanayake, T. and K. P. Esselle, "Prediction of the notch frequency of slot loaded printed UWB antennas," IEEE Trans. Antennas Propag., Vol. 55, No. 11, 3320-3325, Nov. 2007.
doi:10.1109/TAP.2007.908792

13. Zheng, Z. A., Q. X. Chu, and Z. H. Tu, "Compact band-rejected ultrawideband slot antennas inserting withλ/2 and λ/4 resonators," IEEE Trans. Antennas Propag., Vol. 59, No. 2, 390-397, Feb. 2011.
doi:10.1109/TAP.2010.2096399

14. Zhang, S., S. N. Khan, and S. He, "Reducing mutual coupling for an extremely closely-packed tunable dual-element PIFA array through a resonant slot antenna formed in-between," IEEE Trans. Antennas Propag., Vol. 58, No. 8, 2771-2776, Aug. 2010.
doi:10.1109/TAP.2010.2050432

15. Li, J.-F., Q.-X. Chu, Z.-H. Li, and X.-X. Xia, "Compact dual band-notched UWB MIMO antenna with high isolation," IEEE Trans. Antennas Propag., Vol. 61, No. 9, 4759-4766, Sep. 2013.
doi:10.1109/TAP.2013.2267653

16. Blanch, S., J. Romeu, and I. Corbella, "Exact representation of antenna system diversity performance from input parameter description," Electron. Lett., Vol. 39, No. 9, 705-707, May 2003.
doi:10.1049/el:20030495

Dr. Yan Zhang

Dr. Bingjian Niu