Abstract: The reflector-provided dipole-antenna shows outstanding performance in a wide frequency range and allows simultaneous transmission and reception at different frequencies. A dipole antenna element is provided at the back of a dielectric substrate set to the reflector surface. A parasitic element is provided on the front of the dielectric substrate, which is constituted by forming and protruding the central portion of a linear conductor forward in an almost trapezoidal shape, for example. The protruded portion is set to a position corresponding to the front of the feed point of the dipole antenna element and the portions of the said parasitic element towards the ends are set to positions corresponding to the rear of the dipole antenna element. A feed circuit provided on the face side of dielectric substrate is connected to a coaxial connector provided at the back of the reflector.

Abstract: The present invention relates to a compact, lightweight microstrip antenna that operates at two frequencies that are widely different. On a dielectric substrate are formed an element consisting of an annular conductive pattern, wherein a central edge side thereof is short-circuited to a ground electrode, and an element consisting of a circular conductive pattern within the annular conductive pattern. The circular conductive pattern is accommodated within the annular conductive pattern. The two antennas operate at different frequencies, with the element formed by the annular conductive pattern resonating in TM.sub.11 mode and the element formed of the circular pattern resonating in the TM.sub.01 mode. An antenna capable of being used in common by systems with widely different frequency bands, such as the GPS and VICS, is thus obtained.

Abstract: A conductive layer is formed on one surface of an insulating substrate. Notches are formed in the conductive layer to be axially symmetric at equal angular intervals of 120.degree.. A feeding line of a notch antenna is formed on the other surface of the substrate. The feeding line has a C-shape and wide portions for adjusting the phases of excitation of the notches, and receives power at its one point. A ground plate is arranged to be parallel to the substrate. A feeding rod is connected to the conductive layer. The conductive layer and the ground plate are short-circuited by impedance matching pins. The matching pins are integrally formed with the ground plate. The notches and the feeding line constitute an notch antenna, and the feeding rod, the ground plate, the conductive layer, and the matching pins constitute a capacity loaded monopole antenna. To resonate these antennae at a plurality of resonant points, slits are formed in the conductive layer to be axially symmetric at equal angular intervals of 120.