| The wireless communication services have been rapidly growing since its first appearance. The initial establishment of the small radio paging system in Shanghai marks the start of Mobile communication in China. When the mobile phone was invented, it has changed and dominated the world of communication. Then 2G technology brought in voice services, short message service and fax services. Soon followed by 3G, more services were provided to people besides voice service. Such as video services, fast web browsing, e-mail,multimedia messaging services, games and other entertainment services. The mobile communication has now entered into 4G era, the demand of data transmission rate is becoming higher and higher.With the diversity of the mobile data services and enhancements of functionalities, the number of mobile users is rapidly growing, meanwhile, the demand for indoor communication is also growing. The requirement of data transfer rate, system capacity, and performance etc are increasing. To better meet the demand for indoor communication,different kinds of ceiling mount antennas were mounted indoors by many operators. There are WLAN antennas, voice call antennas and so on. To cover different frequency bands for different applications, several ceiling mount antennas are often installed in the same indoor environment; this not only compromises the interior design of the room, but also causes a waste of space. So It will be much more desirable that if a single ceiling antenna would cover entire frequency band, and offer miniaturization and high indoor performance.The dual-polarized antenna can realize polarization diversity and greatly compensate multipath fading. It also can expand system capacity, reduce the number of antennas, cut the cost of system construction. But the size of the dual polarized indoor ceiling antenna is large and its bandwidth is limited. In order to solve the problems of the indoor ceiling mounted antenna, such as narrow band, single polarization, big dimension, this paper presents three kinds broadband dual polarized omnidirectional ceiling antennas. Both the vertical and horizontal polarization units can cover 1710-2690 MHz. First one, both the vertical and horizonatal polarization units are microstrip antennas. It is convenient and inexpensive to manufacture. It has light weight and is easy to install with low roundness and good omni-directionality. The second and third ones are designed with microstrip horizontal unit and dis-cone antenna unit. Both antennas exhibits low cross polarization levels of less than20 dB, and low profile. Finally, the antenna with best performance is fabricated and tested.There is a good consistency between simulation and experiment results, which proved theproposed antenna can be used in the actual environment. |
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