一种地板加载可变电容的频率可重构天线研究

Research of a frequency reconfigurable antenna with varactor-loaded on the ground

研制了一种地板加载可变电容的频率可重构微带贴片天线,该天线在UMTS（1 920-2 170 MHz）频段内连续可调。在方形贴片背面的地板上开一个矩形槽,加载一对可变电容,可以有效增长贴片表面电流的路径。通过控制可变电容两端的直流电压,改变可变电容的电容值,可使天线的工作频率连续可调。由于矩形槽和可变电容不在辐射贴片上,无需设计直流隔离区和偏置电路,降低了天线结构的复杂度。实验结果表明,天线在工作频段内的阻抗匹配良好,S11最低值小于–20 dB,各个工作频点的辐射方向图几乎不变,最大增益约为4.3 dB,可以应用在现代无线通信系统中。

A frequency reconfigurable microstrip patch antenna with varactor-loaded on the ground plane was designed The antenna frequency can be tuned continuously in the range of UMTS band（ 1 920-2 170 MHz）. The surface current path on the patch could be lengthened if a rectangular slot with a pair of varactors was loaded on the ground of the antenna. The capacitance values were changed by controlling the DC voltage supplied to the varactors, so the operation frequency of the antenna could be tuned continuously. Because the slot and varactors were on the ground plane, DC isolation area and bias circuit were omitted. Thus, the complexity of the antenna structure is reduced. The measured results show good impedance match in the operation frequency band. The lowest return loss is less than -20 dB and the maximum gain is about 4.3 dB. Radiation patterns at each work frequency almost are the same. This antenna can be used in the modem wireless communication systems.