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In this article, a small-size printed monopole embedded with a printed narrow strip as a distributed inductor for application in the mobile phone to achieve GSM850/900/1800/1900/UMTS pentaband wireless wide area network operation is presented. With the printed distributed inductor, the fundamental (lowest) resonant mode of the proposed antenna can be effectively shifted to lower frequencies with a wide operating bandwidth, owing to the contributed inductance of the printed distributed inductor compensating for the increased capacitance resulting from the decreased resonant length of the monopole. In this study, the proposed antenna can be printed on the small no-ground portion of size 14 Â 40 mm 2 on the main circuit board of the mobile phone, making it easy to fabricate at low cost and generally showing no thickness above the circuit board; the latter is very attractive for thinprofile mobile phone applications. The proposed monopole antenna is studied in detail in this article. The results also show that the antenna is very suitable to be placed at the bottom of the mobile phone; in this case, the antenna meets the specific absorption rate limit for practical applications.

analyzed. In Figure 3, the surface current distributions at 5 GHz and 8 GHz are shown for when the radiator 1 is excited and radiator 2 is terminated to 50 ⍀ load. The current distributions near radiator 2 for the antenna with stubs are much smaller than those in the antenna without stubs, and the strong current distributions are observed on the three stubs. Similarly, Figure 4 shows the distributions of the surface current at 5 GHz and 8 GHz when port 2 is excited. Adding stubs on the ground plane, the current distributions near the radiator 1 are substantially decreased. The Sparameter characteristics for the proposed antennas with and without stubs are given in Figure 5. As shown in Figures 3 and 4, the isolation characteristics are very sensitive to the existence of stubs in the ground plane. The existence of stubs changes the surface current distributions on the radiating elements and the ground plane. In turn, the isolation characteristic between the two radiating elements is improved. The addition of stubs also lowers the lowest resonant frequency. DIVERSITY ANTENNA CHARACTERISTICSTo validate the performance of the proposed diversity antenna, the HP8719ES vector network analyzer was used to measure the S-parameter characteristics of the fabricated antenna. As shown in Figure 6, it is clearly observed that UWB operation is achieved. Measured results show that the proposed antenna satisfies the 10 dB return loss (S 11 and S 22 ) requirement in the frequency bandwidth from 2.27 GHz to 10.2 GHz, and high isolation characteristics (S 12 and S 21 ) are observed. Figure 7 plots the radiation patterns for the proposed antenna on the x-z and y-z planes at 5 GHz and 8 GHz. As it is shown in Figure 7, the radiation patterns are quasi-omnidirectional in the x-z plane. Figure 8 shows the measured antenna gain in the operating frequency band.The antenna gain variation for each radiating element is less than 1.5 dB within the UWB. CONCLUSIONThe two-elements diversity planar antenna for UWB applications in a PDA phone has been designed and manufactured. By adding stubs on the ground plane, the high-isolation characteristic between the two radiating elements is obtained. Also, quasi-omnidirectional radiation patterns and flat gain variations are achieved in the operating frequency bands. ANALYSIS OF DIELECTRIC RESONATOR ANTENNA EXCITED BY

An on-board small-size printed two-strip monopole antenna integrated with a universal series bus (USB) connector and generating two wide operating bands to cover penta-band wireless wide area network operation in the 824-960/1710-2170 MHz bands is presented. The two strips of the antenna are respectively printed on two small no-ground portions of 15 Â 25 and 15 Â 15 mm 2 (total size 600 mm 2 ). In-between the two printed strips, there is a protruded ground of 15 Â 10 mm 2 to accommodate a USB connector, which serves as the data port of the mobile phone. Also, easy control of the antenna's two wide lower and upper bands can be achieved by respectively adjusting the longer and shorter strips of the printed monopole antenna. That is, the antenna is easy to fabricate and also easy to fine-tune in practical applications. Details of the proposed antenna are presented and discussed. The radiation characteristics of the antenna, including the specific absorption rate results with the presence of the user's head and hand, are also studied.

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