A design for dual-band circularly polarized microstrip antennas with different radiation patterns is described. The design is based on a stacked patch antenna composed of an upper circular patch and a lower ring patch. For the higher operation band, the two patches are simultaneously resonant at the TM21 mode and the stacked patch antenna can produce a conical radiation pattern. As for the lower operation band, only the upper patch is resonant at its fundamental mode and a broadside radiation pattern is obtained. To allow the two radiation patterns to be with circular polarization, 90° hybrid couplers are used to excite the patch antennas at the two operation bands. A prototype designed at the GPS and WLAN bands is constructed. The experimental results demonstrate that the prototype operated at each frequency band has a 3dB-axial-ratio bandwidth of more than 15%. Simulation performed with HFSS also validates the measured results.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Electrical and Electronic Engineering