In-vehicle antenna device

An in-vehicle antenna device comprising:

• a dielectric element having a front surface, first and second side surfaces and a rear surface, wherein a distance between the front surface and the rear surface is substantially equal to a product of one-fourth of a wavelength of an electromagnetic wave and a shortening ratio of the wavelength of the electromagnetic wave passing through the dielectric element, and wherein the dielectric element includes a power supply point disposed on both of the first and second side surfaces, a first conductive surface disposed on the first side surface, a second conductive surface disposed on the second side surface, and a third conductive surface disposed on the rear surface;
• and
• an antenna element including a base element and a branch element, wherein the base element is coupled with the power supply point at one corner of the front surface, wherein the branch element is connected to the base element and has an end opposite to the base element, and wherein a part of the branch element moves apart from one of the first and second conductive surfaces as it goes from the base element to the one end of the branch element,
• wherein the front surface of the dielectric element is attached to a windshield of a vehicle near a corner, at which a roof and a pillar of the vehicle intersect.