This paper describes the design of the disk-loaded monopole with a parasitic array for beam switching. Usually the radiation pattern of a single element such as a λ/4 monopole and the disk-loaded monopole provide low values of gain. The beamwidth is normally large and the coverage is wide. This may be appropriate in an on-body channel where the antenna orientation may not be easily controlled, such as when the users put the terminal in their pocket. In some non-body applications such as WLAN, it is necessary to design antennas with high gain to meet other demands such as high capacity or long range. Also, in the on-body environment it is essential to have such gain in order to minimize the path loss between the antennas, and hence increase the battery life. The antenna was excited using coaxial cable produced more gain and pattern compared to the single element top disk-loaded antenna. The reduced-size antenna namely a sector antenna array also has been discussed in detail in this paper. Such design has allowed at least 50% of the size reduction. The simulation results have shown very good agreement with the measurement for both antennas.
2. Sim Simpson, T. L., "The disk loaded monopole antenna," IEEE Transactions on Antennas and Propagation, Vol. 52, No. 2, 542-550, Feb. 2004.
3. Balanis, C. A., Antenna Theory Analysis and Design, 2nd edition, John Wiley & Sons Ltd., 1997.
4. Cheng, D. K., "Gain optimization for Yagi-Uda arrays," IEEE Antennas and Propagation Magazine, Vol. 33, No. 3, 42-46, June 1991.
5. Ozdemir, M. K., H. Arslan, and E. Arvas, "Mutual coupling effect in multiantenna wireless communication systems," Global Telecommunications Conference, 2003. GLOBECOM '03. IEEE, Vol. 2, 829-833, Dec. 1-5, 2003.
6. Ali, M. A. and P. Wahid, "Analysis of mutual coupling effect in adaptive array antennas," Antennas and Propagation Society International Symposium, 2002. IEEE, Vol. 1, 102-105, 2002.
7. Min, K. S., D. J. Kim, and Y. M. Moon, "Improved MIMO antenna by mutual coupling suppression between elements," The European Conference on Wireless Technology, 125-128, Oct. 3-4, 2005.
8. Parsons, J. D., The Mobile Radio Propagation Channel, 2nd edition, John Wiley and Sons Ltd., 2000.
9. Preston, S. L., D. V. Thiel, T. A. Smith, S. G. O'Keefe, and J. W. Lu, "Base-station tracking in mobile communications using a switched parasitic antenna array," IEEE Transactions on Antennas and Propagation, Vol. 46, No. 6, June 1998.
10. Qian, Y., W. R. Deal, N. Kaneda, and T. Itoh, "Microstrip-fed quasi-Yagi antenna with broadband characteristics," Electronics Letters, Vol. 34, No. 23, 2194-2196, Nov. 12, 1998.
11. Padhi, S. K. and M. E. Bialkowski, "Parametric study of a microstrip Yagi antenna," Microwave Conference, 2000, Asia-Pacific, 715-718, Dec. 3-6, 2000.
12. Song, H. J., M. E. Bialkowski, and P. Kabacik, Parameter study of a broadband uniplanar quasi-Yagi antenna, 13th International Conference on Microwaves, Radar and Wireless Communications, 2000. MIKON-2000, Vol. 1, 166-169, May 22-24, 2000.
13. Deal, W. R., N. Kaneda, J. Sor, Y. Qian, and T. Itoh, "A new quasi-Yagi antenna for planar active antenna arrays," IEEE transactions on Microwave Theory and Techniques, Vol. 48, No. 6, 910-918, June 2000.
14. Kretly, L. C. and A. S. Ribeiro, "A novel tilted dipole quasi-Yagi antenna designed for 3G and Bluetooth applications," Microwave and Optoelectronics Conference, 2003. IMOC 2003. Proceedings of the 2003 SBMO/IEEE MTT-S International, Vol. 1, 303-306, Sept. 20-23, 2003.
15. Huang, J. and A. C. Densmore, "Microstrip Yagi array antenna for mobile satellite vehicle application," IEEE Transactions on Antennas and Propagation, Vol. 39, No. 7, 1024-1030, July 1991.
16. Huang, J., "Planar microstrip Yagi array antenna," Antennas and Propagation Society International Symposium, 1989, AP-S. Digest, 894-897, June 26-30, 1989.
17. Schlub, R. and D. V. Thiel, "Switched parasitic antenna on a finite ground plane with conductive sleeve," IEEE Transaction on Antennas and Propagation, Vol. 52, No. 5, 134-1347, May 2004.
18. Kawakami, H. and T. Ohira, "Electrically steerable passive array radiator (ESPAR) antennas," IEEE Antennas and Propagation Magazine, Vol. 47, No. 2, 43-49, Apr. 2005.
19. Lu, J., D. Ireland, and R. Schlub, "Dielectric Embedded ESPAR (DE-ESPAR) antenna array for wireless communications," IEEE Transactions on Antennas and Propagation, Vol. 53, No. 8, Part 1, 2437-2443, Aug. 2005.
20. Islam, R. and R. Adve, "Beam-forming by mutual coupling effects of parasitic elements in antenna arrays," Antennas and Propagation Society International Symposium, IEEE, Vol. 1, 126-129, June 16-21, 2002.
21. Kumar, G. and K. Gupta, "Nonradiating edges and four edges gap-coupled multiple resonator broad-band microstrip antennas," IEEE Transaction on Antennas and Propagation, Vol. 33, No. 2, 173-178, Feb. 1985.
22. Gray, D., J. W. Lu, and D. V. Thiel, "Electronically steerable Yagi-Uda microstrip patch antenna array," IEEE Transactions on Antennas and Propagation, Vol. 46, No. 5, 605-608, May 1998.