A reconfigurable design for circularly-polarized (CP) slot antennas with dual-frequency operation is presented in this article. The proposed antenna structure is composed of an annular-ring slot, fed by an L-shaped strip, and four parasitic patches, symmetrically placed along the circumference of the ring slot. The slot antenna operates at a one-wavelength resonant mode, and its resonant frequency has a noticeable reduction with increasing the dimensions of the parasitic patches. Furthermore, while the resonant frequency is decreased, both good CP radiation and impedance matching can be simultaneously obtained as long as the open-stub length of the L-shaped strip is properly selected. For the proposed antenna, the effects of various parasitic-patch dimensions on resonant frequency are investigated, and the obtained results indicate that the resonant frequency ranges between 1050 and 1665 MHz as the length of the parasitic patches is changed. Therefore, a CP antenna with the capability of switching between two operating frequencies can be realized by employing diodes to reconfigure the length of the parasitic patches. A prototype designed for the dual-frequency operation (L1/L2) of the Global Positioning System is implemented. Details of the antenna designs and experimental results are presented and discussed.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Electrical and Electronic Engineering