利用微带圆环天线优良的多模特性，设计了一种基于八分之一圆环的微带天线。天线由1个八分之一(45°)的圆环，1条位于天线中心区域的窄缝和1排靠近天线边缘的短路钉组成。这些附加在天线上的缝隙和短路钉起到了激发环形微带天线多模特性的作用，并进一步减小了天线尺寸。本文研究了这些附加结构对环天线的影响，并经过仿真、优化获得了具有3个频点的微带天线。天线的实测结果表明，该天线可以很好地工作在0.9 GHz,1.8 GHz和2.4 GHz，增益分别达到了4 dBi,5 dBi,6 dBi，工作带宽分别为7 MHz,12 MHz和20 MHz。

A triple-band microstrip antenna is designed using the characteristic of a microstrip ringantenna. The proposed antenna consists of a 1/8(45°) ring antenna, a ring slot in the center and an array ofshorting-pins placed on the edge of the patch. The slot and the shorting-pins in the patch can excite threeresonant frequencies and decrease the physical size of the proposed antenna. The influences of thoseadditional structures on the performance are studied. And the triple-band antenna is designed based on thestudies. There is a good agreement between the experiment results and the simulation results. Theproposed antenna can operate at 0.9 GHz, 1.8 GHz and 2.4 GHz with operating bandwidth of 7 MHz,12 MHz and 20 MHz，respectively. Their measured gain are about 4 dBi,5 dBi and 6 dBi，respectively.