A meander annular-ring slot antenna for circularly polarized radiation

This paper presents a novel design of meander annular-ring slot antenna for circular polarized radiation. This antenna operates in the ISM (Industrial, Scientific and Medical) frequency bands, near 915 MHz. The circular polarized radiation is achieved by feeding two orthogonal sides of an annular-ring slot. The required phase difference is achieved by adjusting the position of the feeding port. A meander technique is used in order to reduce the volume of the antenna. Experimental results show that a 3 dB axial ratio bandwidth of 10 MHz has been achieved by this antenna. This type of antenna can be used to enhance the wireless signal coverage of the indoor environment.