BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to an antenna apparatus.

Description of the Background Art

Conventionally, there has been an antenna apparatus that transmits and receives radio waves in a millimeter wave band and a microwave band. Such an antenna apparatus has been widely used, for example, in an on-vehicle radar apparatus, and the like. As for the antenna apparatus, a technology of connecting a line formed on a dielectric substrate, through which signals propagate, to a radiating element for transmitting and receiving radio waves has been known.

However, in the conventional technology, there has been a problem that signals are not sufficiently supplied from the line to the radiating element (or the radiating element to the line). For example, when electric power is not sufficiently supplied to the radiating element, a beam pattern of a radar apparatus, or the like, collapses, so that various antenna characteristics, such as a side lobe ratio and an antenna gain itself, may deteriorate.

SUMMARY OF THE INVENTION

According to one aspect of the invention, an antenna apparatus includes a linear feed line and a radiating element that protrudes laterally from a first side of the feed line. The radiating element is formed by a conductive pattern, and an opening pattern is located in a portion of the feed line from which the radiating element protrudes. The opening pattern extends into a portion of the radiating element.

Thus, it is possible to distribute a desired amount of electric power to the radiating element.

According to another aspect of the invention, the antenna apparatus further includes impedance matching elements that match an impedance of the radiating element. The impedance matching elements are located a predetermined distance away from the radiating element having the opening pattern. A plurality of the radiating elements is provided to the feed line at predetermined intervals, and the feed line is bent together with the impedance matching elements at a location that is between two of the radiating elements that are adjacent to each other.

Thus, a length of an antenna element in an extending direction can be shortened, so that an antenna apparatus can be downsized.

Therefore, an object of the invention is to provide an antenna apparatus that can distribute a desired amount of electric power to the radiating element.

These and other objects, features, aspects and advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

