Abstract: In an antenna unit, the generation of capacitances between each of the open ends of first and second microstrip antennas and a control electrode is controlled by turning a switch on and off, both antenna frequencies being simultaneously changed.

Abstract: A compact surface-mounted antenna having a wide frequency band. In the surface-mounted antenna, a first radiation electrode is formed on the left-half region of the upper surface of a base dielectric substrate. A multi-layer dielectric substrate is laminated on the upper surface of the base dielectric substrate to be bonded and fixed thereto. A second radiation electrode is formed on the right-half region of the upper surface of the multi-layer dielectric substrate. The first and second radiation electrodes are not vertically opposed to each other. Opposing edges of the first and second radiation electrodes are oblique lines. A feeding signal of a signal source is supplied to the first radiation electrode by coupling from a feeding connection electrode, and then, is supplied to the second radiation electrode from the first radiation electrode by another coupling between the first and second radiation electrodes.

Abstract: An antenna device comprising: a feeding radiation electrode and a non-feeding radiation electrode separately disposed on a surface of a dielectric substrate; a short circuit part of the feeding radiation electrode and a short circuit part of the non-feeding radiation electrode adjacently disposed to each other on one side surface of the dielectric substrate; and an open end of the feeding radiation electrode and an open end of the non-feeding radiation electrode disposed on mutually different surface sides of the dielectric substrate other than the surface on which said short circuit parts are disposed.

Abstract: A surface mount antenna, comprising: a base, comprising an insulator having a first main face, a second main face and end faces extending between said first main face and second main face, a ground electrode provided on the first main face of said base, first and second radiation electrodes, provided on the second main face of said base, and a first connection electrode, a second connection electrode and a feed electrode, provided on end faces of said base, said first and second radiation electrodes facing each other with a slit in between, said slit being provided at a diagonal to all sides of the second main face of said base, the slit having first and second ends extending to end portions of the second main face, an end of said first radiation electrode which is near to the first end of said slit connecting to said ground electrode via said first connection electrode, said feed electrode being provided near to an end portion of the first radiation electrode, with a gap provided between the feed electrode a