Low-profile and small-sized spiral-shaped microstrip line antenna with multi-band operation in UHF frequency band

摘要

Generally, small-sized antennas are needed for specified low-power radio applications, especially automobile applications. Because such antennas were usually placed on the neighborhood of metal surfaces such as housings and ground planes, an antenna, being hard to be influenced from neighboring conductors, is desired. Having this fact in mind, the spiral-shaped microstrip line antenna consisting of two radiation elements being set on the surface 10 mm away from the ground plane was proposed and its performance was numerically and experimentally investigated to realize a low-profile antenna with multi-band operation in UHF band. This antenna was installed in the automobile, and the radiation patterns were evaluated.