Moreover, we would like to note that the folded antenna has much smaller size than the unfolded antenna, in addition to the bandwidth improvement in the DCS band.An absolute gain including the return loss and radiation efficiency was measured. The measured radiation patterns for the proposed antenna at 1 and 2 GHz are presented in Figure 6. The radiation patterns of H, E1, and E2 planes were measured in the x-y, z-x, and y-z planes, respectively. In the x-y plane, the radiation pattern at 1 GHz had quite good omni-directional characteristics. The radiation pattern gets more directional in the high-order resonant 2 GHz band. For the GSM and DCS bands, maximum absolute antenna gains (G 0abs ) were Ϫ0.05 and Ϫ0.13 dBi, respectively. These radiation patterns show that the proposed antenna had a good radiation efficiency.
CONCLUSIONA dual-band small chip antenna was designed to satisfy requirements for operation in the GSM and DCS bands. The impedance bandwidth and resonant frequency of each band was controlled by the intercoupling capacitance of the metallic structure. The intercoupling capacitance was created by folding a metallic structure. The resonant frequencies were nonuniformly shifted due to the intercoupling capacitance. This property was very useful in controlling the resonance frequencies and their corresponding bandwidths. The simulated and measured results show that the proposed antenna satisfies the requirements for both GSM and DCS bands simultaneously. This resonanceshift effect caused by the folding intercoupling capacitance can be usefully exploited in designing a multiband antenna with high-order resonance phenomena. printed monopole, Electron Lett 28 (1992), 1326 -1327. 4. M. Makimoto and S. Yanashita, Microwave resonator and filters for wireless communication, Springer Verlag, New York, 2000, pp. 84 -87. 5. C.A. Balanis, Antenna theory and analysis and design, Wiley, New York, 2005, pp. 177-217. ABSTRACT: Dielectric resonator-loaded circular microstrip patch antennas can be used as an alternative way to generate circular polarization. The dielectric resonator is placed on the edge of the circular microstrip patch antenna to result both strong coupling effect and two degenerated orthogonal modes. Then, we choose the feeding point, the placed position and size of DR, and the height of antenna as key tuning parameters; both wide circular polarization and impedance matching are achieved. Application is given for WLAN 2.4 GHz band. Both simulated and measured data are matched well. Measured results show that the center frequency is at 2.45 GHz. The impedance bandwidth is 19.2%. Besides, the axial ratio bandwidth is 3.7% (2.39 -2.48 GHz). The radiation patterns are broadside radiations and high antenna gain of 8.6 dBic is achieved.