Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/1271—Supports; Mounting means for mounting on windscreens
  • H01Q1/1278—Supports; Mounting means for mounting on windscreens in association with heating wires or layers

Definitions

• the present invention relates to antennas fitted to motor vehicles, more particularly to the screen-printed antennas on the rear window of such vehicles and especially of saloon type motor vehicles.
• the antennas intended to be mounted on board passenger or utility vehicles are increasingly integrated so that they are no longer visible from the outside of the vehicle, allowing the latter to present a more harmonious appearance, in agreement with the current tastes of the public.
• the drawbacks associated with the use of protruding equipment, which relate to aerodynamics, noise, vibration, sealing and vandalism, are thus greatly reduced. It is important that the antenna is placed in an environment such that it can continue to perform its essential function which consists in transducing an electromagnetic field (external to the vehicle) into an electrical signal which can be used by radio equipment.
• the FM and SERVITUDE antennas are with linear terrestrial polarization and the reference is an antenna of length equal to a quarter of the wavelength (ie a length of approximately 750 mm for FM and 170 mm for SERVITUDE).
• the current state of the art offers many possibilities for so-called hidden antennas, in particular for the following three radio reception functions: FM radio (Frequency modulation between 76 MHz and 108 MHz); - AM radio (Amplitude Modulation) between 140 kHz and 1.7 MHz); - SERVITUDE function 434 MHz (or 315 MHz for Japan).
• the radiative part of these antennas consists of conductive lines screen printed on the glass part of the vehicle which then serves as a support. The lines have a thickness of 0.8 mm allowing the passage of sufficient and acceptable current for the proper functioning of the defrost.
• the rear window is used as a support for the multi-antenna system.
• each of the FM, AM and SERVITUDE hidden antenna functions implements an aerial and an electronic circuit as close as possible to it.
• the aerial of the AM antenna is formed by one or more horizontal conductive lines with a thickness of approximately 0.8 mm in the upper or lower part of the rear window. These screen-printed lines do not participate in the defrosting function.
• the electronic unit includes an electronic circuit carrying out a high impedance adaptation from the air to the radio receiver;
• the aerial of the FM antenna is made up of a number of horizontal conductive lines varying between a minimum of 15 and a maximum of 25. These lines, about 0.8 mm thick, also participate in the defrosting function .
• the electronic unit comprises a circuit carrying out the adaptation of the impedance of the aerial to the characteristic impedance of the coaxial cable leaving the unit, that is to say equal to a value as close as possible to 75 ohms.
• the SERVITUDE antenna aerial can be the same as the AM aerial or the FM aerial.
• the electronic unit includes an electronic card which adapts the impedance of the aerial to the impedance of the coaxial cable leaving the housing, that is to say close to 50 ohms.
• This box is said to be passive or active depending on whether a + 12V power supply is used coming directly or indirectly from the vehicle battery.
• the function of the active box is to amplify the signal with the use of one or more transistors.
• the choice to use a active or passive electronic unit is made according to the average gain calculated compared to a reference antenna (quarter wave antenna). In general, the minimum acceptable gain with respect to the reference antenna is around -10dB. The average gain is obtained by calculating the average of the 360 measurement values (one measurement at each degree around the vehicle). If with a passive box the antenna is below this limit of -10dB, we generally go to an active box to compensate for the missing dB.
• FM reception is improved by combining different antennas, for example up to four antennas, called FMI, FM2, FM3 and FM4. These different antennas use the same support of the rear window and are differentiated by their collecting point, these collecting points on the rear window then create four different electromagnetic responses.
• the object of the present invention is to propose a screen-printed antenna device for the rear window of a saloon-type motor vehicle, of the general known type mentioned above and which, while ensuring excellent reception of signals both in modulation frequency and amplitude modulation than in the easement function, is of a design and installation which are particularly simple and economical.
• the screen-printed antenna on the rear window of a saloon-type motor vehicle has four radio reception functions, namely AM, FMI, FM2 and SERVITUDE, and comprises: - an AM antenna comprising an aerial consisting of at least one horizontal conductive line disposed in the upper or lower part of the rear window and not participating in the defrosting function, the aerial of the AM antenna being associated with a first electronic circuit disposed in an electronic unit and performing a high impedance adaptation of said overhead to a radio receiver; - FMI and FM2 antennas comprising the same aerial consisting of several horizontal conductive lines which participate in the defrosting function, these two antennas having different signal collecting points (12, 13), and each comprising an electronic unit circuit carrying out the adaptation of their aerial impedance to the characteristic impedance of the coaxial cable leaving the electronic unit; and - a SERVITUDE antenna comprising the same aerial as that of the AM antenna, a circuit of the electronic unit carrying out the impedance adaptation of the aerial of this antenna to the impedance of the coaxial
• each pair of vertical lines of the aerial of the FMI and FM2 antennas is placed approximately 510 mm from the middle of the corresponding defrost collector.
• - the electronic circuit of the FMI antenna is a passive circuit while the electronic circuit of the FM2 antenna is an active circuit; and - the electronic circuit of the AM antenna is an active circuit, and the electronic circuit of the SERVITUDE antenna is a passive circuit.
• the electronic unit is constituted by a single card comprising the four electronic circuits of the antennas FMI, FM2, AM and SERVITUDE, the points collecting signals on the aerials of these antennas being grouped in the same sector of the rear window of the vehicle to make the length of the connection wires from the rear window to said housing as short as possible.
• FIG. 1 is a front view of a rear window of an automobile sedan equipped with a screen-printed antenna system according to the present invention
• FIG. 2 is an enlarged representation of the lower part of the screen-printed antenna of FIG. 1.
• a first FMI frequency modulation antenna comprises an aerial consisting of the original deicing network 2 to which are added two pairs of vertical lines 9, 10 which are symmetrical with respect to the median vertical longitudinal plane of the window 1.
• An electronic unit 11 adapts the impedance of the FMI antenna to 75 ohms.
• a second FM2 frequency modulation antenna includes the same aerial as that of the FMI antenna and an active electronic unit.
• the FM2 signal collected at 13 is transmitted to the electronic unit 11 which adapts the FM2 antenna to 75 ohms and amplifies the signal.
• the point 13 is arranged on the collector 4 which is on the same side as the housing 11, so that the connection between this point 13 and the housing 11 takes place by a single wire 14 of approximately 300 mm.
• a third AM amplitude modulation antenna is composed of an AM aerial and an active adaptation box.
• the AM aerial consists of horizontal lines
• a fourth SERVITUDE antenna is composed of a SERVITUDE aerial and a passive adaptation box.
• the SERVITUDE aerial consists, like the AM aerial, of screen-printed horizontal lines 15, the signal collecting point also being at 16.
• a filter 8 is interposed between the supply battery 7 and the midpoint 6 of the defrost collector 3.
• This filter 8 which is composed of an inductive element and a capacitive filter element connected to the chassis of the vehicle, ensures correct operation of the antenna system by preventing the radiofrequency signal is conducted, by the defrost supply wires, to the battery 7.
• the electronic unit 11 consists of a single electronic card comprising four circuits, that is to say: a circuit for the AM function, which is connected to point 16 by a connection wire 17; a circuit for the FMI function, which is connected to point 12 of the FMI aerial by a connection wire 19; - a circuit for the FM2 function, which is connected to point 13 of the aerial FM2 by wire 14; and a circuit for the SERVITUDE function, which is connected to point 16 by the connection wire 17, like the circuit for the AM function.
• the wires 14, 17 and 19 are provided as short as possible, that is to say not greater than 300 mm, to avoid losses in FM and AM.
• the electronic unit 11 is advantageously arranged in the vicinity of the lower part of the rear window of the vehicle, to the right or to the left.
• This housing 11 is rectangular in shape and is preferably placed on the metal rear plate or on the metal upright adjacent to the rear window. It is fixed by a screw to the chassis, which then serves to obtain the ground signal.
• a thick screen-printed mass line 20 with a thickness for example of approximately 15 mm, is in contact with the adhesive 21 ensuring the fixing of the rear window 1 on the chassis.
• This ground line 20 and a screen-printed line 22 at the bottom of the window form a transmission line for the FMI radiofrequency signal.
• the FMI signal is thus transmitted from the side of the electronic unit 11, so that a single wire 19 (with a length of approximately 150 mm) takes the signal at point 12 and brings it to the housing 11.
• the collecting point 16 which extracts the AM and SERVITUDE signals by means of a single wire of approximately 150 mm going towards the housing 11.
• the pairs of vertical lines 9 and 10 are respectively placed at a distance L of approximately 510 mm (a quarter of the wavelength) from the media 6, 13 of the defrost collectors (see FIG. 1), which makes it possible to obtain a system of antenna resonating in the FM band having the maximum energy radiated in this band.

Landscapes

• Details Of Aerials (AREA)
• Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34778552

Family Applications (1)

Country Status (6)

Families Citing this family (8)

Family Cites Families (7)

• 2004
  • 2004-02-06 FR FR0401140A patent/FR2866155B1/fr not_active Expired - Fee Related
• 2005
  • 2005-02-07 US US10/586,919 patent/US7348927B2/en not_active Expired - Fee Related
  • 2005-02-07 EP EP05717571A patent/EP1711978A1/fr not_active Withdrawn
  • 2005-02-07 CN CNA2005800041284A patent/CN1918743A/zh active Pending
  • 2005-02-07 JP JP2006551888A patent/JP4195718B2/ja not_active Expired - Fee Related
  • 2005-02-07 WO PCT/FR2005/000268 patent/WO2005078857A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events