关键词: |
GLOBAL POSITIONING SYSTEM, ANTENNA COMPONENTS, ANTENNA CONFIGURATIONS, CIRCULAR ANTENNAS, DIODES, SIMULATION, GROUND LEVEL, METALS, RADIATION, POLARIZATION, SURFACE WAVES, REAL TIME, MODIFICATION, DIELECTRICS, SUBSTRATES, ELECTROMAGNETIC WAVE PROPAGATION, PRINTING, RADIATION PATTERNS, TRANSISTORS. |
摘要: |
Various schemes for the design of recontigurable printed antenna eiements are presented for GPS and other applications. The antenna elements can be linearly or circularly polarized. The physical phenomenon behind these schemes is based on the modification of the EM propagation characteristics of a dielectric substrate by using parasitic metallic strips connected by switches. The switches can be implemented with diodes, transistors or RF MEMS. The switches effectively change the dimensions of the metallic strips causing the radiation of surface waves supported within the substrate. The radiation patterns can be changed in real time by turning the switches on or off. An reconfigurable linearly polarized printed antenna is obtained by using four strips near all four edges of the antenna. On the other hand, a circularly polarized antenna requires a ring completely surrounding the antenna element. To reduce the overall size of the antenna, an alternative configuration having a smaller ground plane and ring is presented. Simulated results, obtained with a FDTD code, are obtained to assess the performance of the various designs. |