多带混合平衡天线

　　多带混合平衡天线

　　小用户设备天线的设计多年来一直依赖于非平衡设计的使用–通常巧妙的变体的单极和倒L天线。为降低设备尺寸、非平衡天线成为越来越严重的问题，因为它们的输入阻抗和辐射性能强烈依赖于地面和他们的位置在它的大小。

　　本文介绍了一种新的多波段天线采用平衡馈电网络显示从通常的接地面的影响，指出新的天线设计方式的实质性免疫，可很少或根本没有修改平台之间移动。为了节省空间，设计包括天线下的一个海湾，以容纳相关的射频电路和设备。

　　Balanced Antennas

　　While an unbalanced antenna has only a single terminal and is driven against the local groundplane， a balanced antenna has two terminals exhibiting equal impedances with respect to the local groundplane. These two terminals are excited with respect to ground by equal voltages with a phase difference of 180°。 This slightly unusual definition makes it clear that there are two ways in which we can imagine a balanced structure （Figure 1b and 1c）。 Figure 1（c） provides a useful insight into an alternative way of realizing a balanced structure by using a complementary pair of unbalanced structures， each of which can use the compressed formats which have become usual in small wireless devices.