| Because of the escalating of mobile communications business in the capacity and quality and the very crowded mobile communication frequency band, Therefore, advanced technology must be used to effectively utilize the limited frequency resources, satisfying the business needs to high-speed and large capacity, while overcoming the multi-path fading of the high-speed data in wireless channels. As restrictions of the mobile terminal antenna in size, weight and cost and so on, technologies and measures to improve the quality of communication depend on the base station antenna. So researching the base station antenna for mobile communication base station antenna system also becomes a hotspot. Most of the current 3G systems put distributed base station antenna to use, the study of distributed mobile communication base station antenna system is of a very important significance to solve the communication problems.Firstly, a two-way and a four-way equal power splitter are proposed for the feed network, and the splitters take up of the bands from 800MHz to 3.36GHz. The splitter is designed with four Chebyshev impedance transformers, and the isolation is improved by using the isolation resistor.Second, the distributed base station with cross polarization technique for 3G mobile communication is designed and fabricated. The antenna consists of four cross-polarized linear elements, with the bandwidth of 1710-2170MHz, the gain of 14dBi, horizontal beamwidth of 65°, port isolation greater than 30dB.Finally, two indoor ceiling mounted antenna are proposed, one with short loaded pin and the other without the pin. The ceiling mounted antenna without short loaded pin works from 800MHz to 2500MHz; the highest gain in the bands is 4.5dB, gain fluctuation±1dB. The other antenna is a dual band antenna, with the bands of 806MHz-960MHz and 1710MHz-2500MHz, and the highest gain in the low and high bands are 11.8dB and 7dB, respectively, gain fluctuation±1dB. |
