REFERENCES 1. P. Parolari, L. Marazzi, D. Rossetti, G. Maier, and M. Martinelli, Coherent-to-incoherent light conversion for optical correlators, J Light- wave Technol 18 (2000), 1284 –1288. 2. C. Skoufis, S. Sygletos, N. Leligou, C. Matrakidis, I. Pountourakis, and A. Stavdas, Data-centric networking using multiwavelength headers/ labels in packet-over-WDM networks: A comparative study, J Light- wave Technol 21 (2003), 2110 –2122. 3. S. Xiao, Q. Zeng, J. Wang, J. Xu, and Y. Wang, Realization of multiwavelength label optical packet switching, IEEE Photon Technol Lett 15 (2003), 605– 607. © 2006 Wiley Periodicals, Inc. MULTIBAND DIAMOND SHAPED SIERPINSKI GASKET MONOPOLE ANTENNA Ali Mirkamali, 1,2 Peter S. Hall, 1 and Mohammad Soleimani 2 1 Department of Electronic, Electrical, and Computer Engineering University of Birmingham Edgbaston, Birmingham, B15 2TT, U.K. 2 Electrical Engineering Department Iran University of Science and Technology Tehran, Iran Received 7 December 2005 ABSTRACT: A multiband diamond-shaped Sierpinski gasket monopole antenna is described. The radiation pattern of wideband monopole an- tennas like the circular-disk and diamond monopole antennas degrades as frequency increases. In this paper, several cutouts based on the Sier- pinski gasket geometry are made in the diamond monopole antenna in order to improve the radiation pattern of the antenna. It is experimen- tally shown that a multiband diamond-shaped Sierpinski gasket mono- pole antenna with a significant improved radiation pattern can be achieved by making cutouts in the diamond monopole antenna. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1069 –1073, 2006; Published online in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/mop.21603 Key words: wideband monopole antenna; diamond monopole; radiation pattern; Sierpinski gasket; multiband 1. INTRODUCTION Multiband and wideband monopole antennas have attracted a great deal of attention for modern wireless communication systems. The circular-disk monopole antenna with a very large impedance band- width was introduced in [1] and further studied in [2]. The pattern of the circular-disk monopole antenna degrades as frequency in- creases. The multiple-ring monopole antenna was proposed in [3]. It consists of a set of self-similar circular rings, which are super- imposed to form the single antenna unit, as shown in Figure 1. The multiple-ring monopole antenna is a multiband antenna and due to the discrete structure of the multiple rings, it shows improved radiation pattern at higher operating bands in comparison to the circular disk. In this paper, the diamond monopole antenna is investigated and several cutouts based on the Sierpinski gasket geometry [4] are made in the antenna in order to improve the radiation pattern at high frequencies. Two diamond monopole antennas with flare Figure 1 Multiple-ring monopole antenna Figure 2 Diamond monopole antennas: (a) flare angle of 60°; (b) flare angle of 90° Figure 3 Diamond-shaped Sierpinski gasket monopole antenna with flare angle of 60° DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 48, No. 6, June 2006 1069