| 摘要 |
PURPOSE: To suppress the radiation of radio waves in the direction of a user by providing plural antennas and a phase shift circuit for exciting the plural antennas with a prescribed phase difference. CONSTITUTION: Two bar-shaped antennas 18 and 19 are erected at the peak part of a communication equipment case body. The antenna 18 is provided on a position close to a front surface and the antenna 19 is provided on the position away from the front surface. The antenna 18 is directly connected to a distribution/synthesis device 21 and the antenna 19 is connected to the distribution/synthesis device 21 through a phase shifter 22. In the case of arranging the antennas 18 and 19 in such a manner, the power distribution ratio of the respective antennas 18 and 19 in the distribution/synthesis device 21 is defined as 1:1. Also, the phase shift amount of the phase shifter 22 is set so as to satisfy conditions indicated by ϕ1 -d/λ=-π including electric length from the distribution/synthesis device 21 to the respective antennas 18 and 19. In this case, ϕ1 indicates the exciting phase of a first element, (d) indicates an antenna interval and 2 indicates a wavelength. Thus, the radiation of the radio waves in the direction of the user is suppressed at the time of communication. |
