| 摘要 |
An antenna for reception of signals in a plurality of frequency bands employed in portable and vehicular communications is constructed of a dielectric layer (34) disposed on a metallic plate (28) which serves as a ground plane. Microstrip antenna elements in the form of a planar radiator (24;24A;112;120;126) encircled by a loop radiator (26;26A;26B) are disposed upon the dielectric layer (34;34,134,132). A rod radiator (22,22A) oriented normally to the plate extends through the planar radiator and the dielectric layer, and is surrounded by a dielectric cylinder (44) which insulates the rod radiator from the planar radiator and the plate (28). The planar radiator may be configured as a patch radiator, a spiral radiator, or a crossed dipole radiator. Also, one or more additional layers of patch radiator elements (128,130) may be stacked upon the patch radiator to provide a stacked microstrip radiator. Terminals (54,56) are positioned about the planar radiator for extracting orthogonal components of a circularly polarized electromagnetic signal. All radiators are smaller than approximately one-half wavelength of the shortest wavelength signal to be received by the antenna. The antenna can be used for receiving vehicular signals such as telephony, keyless door lock operation, ground positioning satellite signals, as well as AM/FM radio. <IMAGE> |
