To provide a planar antenna which can be made compact, without increase in cost and has the advantages of both balanced and unbalanced antennas which are not affected by the ground, and by electromagnetic leakage, even if it is used in compact portable equipment.
In the planar antenna, in which a radiating element of a metal plate and two inverted F antennas on a ground plane are combined on the ground plane to be formed in a symmetrical manner, the ground plane is eliminated to form one balanced antenna having two antenna elements, and a facing projecting part is formed on each of middle parts of the both elements, a coaxial cable 6 is connected to a feeding point P of one projecting part 4 and to the projecting part 5 of the ground side element 3 of the other side, the coaxial cable 6 is taken about on the ground side element 3 of the other side, the base end of a shield casing 6b of the coaxial cable 6 to the center S of a connection part of the two elements 2 and 3, and the length of the coaxial cable 6 taken about on the ground side element 3 of the other side is set to about 1/4 of the wavelength of the frequency to be tuned.
COPYRIGHT: (C)2007,JPO&INPIT
Tadashi Sato
Toshiya Sato
Haruka Oda