Antenna

摘要

A shared antenna communicates radio waves with different frequencies or different polarization characteristics, and has a simple configuration that can be placed in a small device. The antenna includes a plurality of loops of the shape of a cross in a spiral fashion and includes a gap provided at a certain midpoint in the spiral loops and a power supply portion provided in a central portion. The distance of the gap is set such that electromagnetic coupling is caused at a first frequency and no electromagnetic coupling is caused at a second frequency different from the first frequency.

主权项

1. An antenna comprising:
a first antenna portion having a plurality of loops in a spiral fashion and forming a cross shape; a second antenna having a plurality of loops in a spiral fashion and forming a cross shape, the second antenna portion being provided on an outer circumference of the first antenna portion such that the first antenna portion comprises an inner portion of the antenna and the second antenna comprises an outer portion of the antenna, the first and second antenna portions being disposed in a same layer; and a power supply provided on an inner most loop of the first antenna portion and at a central location of the antenna, wherein an outer end portion of the second antenna portion is an open end and an outer end portion of the first antenna portion and an inner end portion of the second antenna portion are separated by a gap interposed therebetween, electromagnetic coupling being caused in the gap at a first frequency, and no electromagnetic coupling being caused at a second frequency different from the first frequency.