| The increasing demand for wireless communication services inspires the need for antennas with high performance such as miniaturization, wideband and/or multi-band. This thesis mainly focuses on the design of various dual-band base station antennas for cellular mobile radios. The author's major contributions are outlined as follows:1. By taking the advantages of the printed dipole such as simple structure and light weight, three types of antenna elements are designed and fabricated. The mutual coupling between the elements in the array can be reduced, because the shape of the printed dipole is modified and then the spacing between elements in the antenna array is decreased. The measured results show that the VSWR is less than 2 in GSM, CDMA, 2.45GHz WLAN, and 3G bands, and the beam width of this antenna in the horizontal plane reaches 120°by introducing the reflector.2. By choosing the best one among these three antennas as the element, a 16-element antenna array is formed. The beam-shaped design of the vertical radiation pattern for the array with equal amplitude and unequal phase excitation is addressed by using Ansoft HFSS 10.0, which makes the array with 0.5λelement spacing meet the design requirements. These results show that the antenna array is suitable for 900/1800MHz cellular mobile radios system with 120°beam width in the horizontal plane.3. For the indoor wireless communication system, a new dual-band antenna with U-shaped reflector is designed. By increasing the thickness of the air medium, the wider frequency band is achieved.4. In order to increase its gain, the antenna with the metamaterial cover is designed. Simulated results show that the gain of the proposed antenna increases about 2.4dB, comparing with the antenna without the metamaterial cover. |
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