Glass antenna
A glass antenna with improved reception sensitivity was provided. A glass antenna formed on a surface of a window of a motor vehicle includes: an FM antenna element; and a heater that is capacitively coupled to the FM antenna element, and includes a plurality of heating wires, wherein a distance S between the FM antenna element and the heater is more than 40 mm.
1. A glass antenna formed on a surface of a window of a motor vehicle including a device that transmits a radio wave in an FM band, the glass antenna comprising:
an FM antenna element;
a heater that is capacitively coupled to the FM antenna element, and includes a plurality of heating wires; and
a noise suppression element located on a side of the heater opposite to the FM antenna element, and affecting noise from the device,
wherein the heater includes at least one vertical element extending in a vertical direction, and
the FM antenna element and the heater constitute an FM antenna reception unit.
2. The glass antenna according to claim 1 , wherein a distance S between the FM antenna element and the heater is more than 40 mm.
3. The glass antenna according to claim 2 , wherein the distance S is 50 mm or more.
4. The glass antenna according to claim 1 ,
wherein the window is a rear window,
the motor vehicle is a hybrid vehicle having an internal combustion engine and an electric motor as drive sources, and includes a driving battery for the electric motor, an auxiliary battery, and a DC-DC converter that converts a voltage of the driving battery into a voltage suitable for the auxiliary battery as the device,
the DC-DC converter is located in a rear part of the motor vehicle, and
a central frequency F of noise generated by driving the DC-DC converter satisfies 76 MHz≤F±7 MHz≤108 MHz.
5. The glass antenna according to claim 1 , further comprising a plurality of noise rejection elements located between the FM antenna element and the heater, and including at least a horizontal element extending in a horizontal direction,
wherein the plurality of noise rejection elements are arranged along the horizontal direction at a predetermined spacing.
6. The glass antenna according to claim 5 , wherein the plurality of noise rejection elements are each connected to a vehicle ground.
7. The glass antenna according to claim 1 , further comprising:
an AM antenna element;
a parallel resonance circuit that is formed by a pattern of an antenna wire connected to the AM antenna element, allows passage of a received signal in an AM broadcast frequency band, and blocks or attenuates a received signal in an FM broadcast frequency band.
8. The glass antenna according to claim 7 , wherein the AM antenna element is located between the FM antenna element and the heater.
9. A hybrid vehicle having an internal combustion engine and an electric motor as drive sources, comprising:
a rear window;
a glass antenna according to claim 1 , formed on a surface of the rear window,
a driving battery for the electric motor,
an auxiliary battery, and
a DC-DC converter that converts a voltage of the driving battery into a voltage suitable for the auxiliary battery as the device,
wherein the heater includes an anode bus bar connected to the auxiliary battery and supplies power to the heater, and a cathode bus bar connected to a vehicle ground,
a noise filter for the FM antenna element is provided between the auxiliary battery and the anode bus bar, the noise filter including a coil element, and
no noise filter is provided between the cathode bus bar and the vehicle ground.
10. The hybrid vehicle according to claim 9 , wherein on the surface of the rear window, a power supplying terminal for supplying power to the FM antenna element is located on a cathode bus bar side.