Communications: radio wave antennas – Antennas – With vehicle
Reexamination Certificate
2000-05-01
2001-10-23
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With vehicle
C343S704000
Reexamination Certificate
active
06307516
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to an antenna system for a vehicle radio and, more particularly, to an antenna system for a vehicle radio in which the antenna elements are embedded in a vehicle window and employ the window defogger heating elements.
BACKGROUND OF THE INVENTION
Automotive vehicles are commonly equipped with a radio and a corresponding antenna system to receive amplitude modulation (AM) and frequency modulation (FM) broadcast radio signals. One conventional vehicle antenna system includes a mast antenna vertically extending from the body of the vehicle. Mast antennas are generally limited in signal performance, add wind noise and drag to the vehicle, and are susceptible to corrosion and damage.
Another conventional vehicle radio antenna includes a backlite antenna system in which antenna elements are embedded in a rear window of the vehicle. Examples of backlite antenna systems are disclosed in U.S. Pat. Nos. 5,610,619, 5,790,079, and 5,099,250. The vehicle antenna set forth in U.S. Pat. No. 5,099,250 utilizes the defogger elements encapsulated in the back window of the vehicle as antenna elements to receive broadcast radio signals. Conventional antenna systems that integrate the antenna with the defogger heating elements in the rear window of a vehicle typically require bifilar or toroidal chokes coupled between the conductive window elements and the vehicle DC power supply to separate the received antenna signal from the high current signals that heat the defogger elements. These chokes provide low impedance paths for the propagation of large current flow necessary to power the defogger heating elements, and high impedance paths against the propagation of the radio signals. The chokes are generally incorporated in an antenna impedance matching network in order to match the output of the antenna elements to the input of the amplifier associated with the vehicle radio to reduce the attenuation of power transfer from the antenna elements to the radio.
Typical impedance matching networks are specially designed and vary from one type of vehicle to other types of vehicles to realize the greatest efficiency in impedance matching. This is generally because the capacitance created between the conductive elements in the vehicle body varies from vehicle to vehicle. Further, prior art antenna grid patterns are often directional at FM frequencies, and have relatively low gain at AM frequencies.
It is therefore desirable to provide for an antenna system that employs the defogger heating elements in a vehicle window, such as the rear window, and includes an antenna impedance matching network that can be incorporated into a variety of vehicles. It is further desirable to provide for such an antenna system that does not require lumped matching components.
SUMMARY OF THE INVENTION
The present invention provides for an antenna system integrated with the defogger heating elements in a window to achieve enhanced impedance matching without requiring lumped matching components. To achieve this and other advantages and in accordance with the purpose of the present invention as embodied and described herein, the present invention provides for an antenna system for a radio of a vehicle comprising a vehicle window, a conductive grid formed in the vehicle window and having a plurality of horizontal and generally parallel conductive elements, first and second bus bars connecting the horizontal conductive elements at opposite ends. The antenna system has first and second vertical conductive elements embedded in the vehicle window and arranged substantially orthogonal to the horizontal conductive elements. A tuning element is coupled to each of the first and second vertical conductive elements and is substantially orthogonal thereto. The tuning element has a length selected so as to substantially match impedance of an RF signal path. The horizontal elements are energized to heat the vehicle window during a defogger heating operation, and also serve to receive radio signals for the radio.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.
REFERENCES:
patent: 5097270 (1992-03-01), Lindenmeier et al.
patent: 5099250 (1992-03-01), Paulus et al.
patent: 5231410 (1993-07-01), Murakami et al.
patent: 5293173 (1994-03-01), Kropielnicki et al.
patent: 5581263 (1996-12-01), Maeda et al.
patent: 5610619 (1997-03-01), Zafar
patent: 5790079 (1998-08-01), Zafar
patent: 5933119 (1999-08-01), Fujii et al.
patent: 6002373 (1999-12-01), Taniguchi et al.
Bally Nazar F.
Schaefer Reed Clinton
Zafar Imtiaz
Delphi Technologies Inc.
Funke Jimmy L.
Nguyen Hoang
Wong Don
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