Communications: radio wave antennas – Antennas – Antenna with parasitic reflector
Reexamination Certificate
1999-05-01
2001-02-20
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Antenna with parasitic reflector
C343S713000, C343S722000, C343S752000
Reexamination Certificate
active
06191751
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to antenna structures, and in particular to dual band directional antenna assemblies. The invention provides particular utility to dual band antennas for use in vehicular applications.
BACKGROUND OF THE INVENTION
Wireless communication is well known for communicating over large distances and also where the communicating devices require a high degree of mobility. Known antenna devices for use in communication systems are capable of resonating at two or more different frequencies. U.S. Pat. No. 4,494,122 to Garay et al. and U.S. Pat. No. 5,406,296 to Egashira et al. disclose two examples of multiple frequency antenna structures. Also known are antenna structures finding particular applicability within the interior portions of vehicles. U.S. Pat. Nos. 5,634,209 and 5,649,316 both to Prudhomme et al. disclose a radio antenna system that can be positioned in a variety of locations within a vehicle interior.
SUMMARY OF THE INVENTION
An antenna structure exhibiting first and second predetermined resonant frequency ranges is disclosed. The present invention includes a directional antenna assembly for use in the cellular telephone and PCS device frequency ranges (800-900 MHz. and 1850-1990 MHz., respectively). The antenna assembly is adapted for in-vehicular use and may be housed within the rear view mirror assembly, the brake light assembly, or a separate housing and dashboard or rear-deck mounted to provide provides thru-glass access. The improvements and benefits of the antenna assembly of the present invention include:
An increased signal strength, resulting in extended signal range and fewer dropped calls for a given power consumption rate;
Reduced radio frequency radiation incident to a vehicle occupant's body, thereby reducing potential health risks;
Reduction in the physical size of a directional antenna;
Improved directionality and gain—reduced rearward radio radiation (front-to-back ratio of 1-10 nominal) and forward gain of 2.7 dBi; and
Reduction in multipath interference, resulting from better call/data quality.
An improved cellular telephone/PCS device antenna assembly is provided for suitable applicability within vehicles. The antenna assembly is attractive, economical, reliable and effective. The inventive antenna assembly is useful in association with many types of vehicles, such as: automobiles, vans, trucks, taxicabs, buses, motorcycles, construction equipment, tractors, and agricultural vehicles.
The cellular telephone and PCS device system has an antenna housing for securing and protecting the antenna components and which may be secured within the vehicle interior. A coaxial cable operatively couples the antenna assembly to the cellular telephone/PCS device.
The antenna structure includes a conductive driven element which is electrically coupled to a feed port of the radio device. An end of the conductive driven element is coupled to a first LC trap structure. The antenna assembly further includes a second LC trap structure aligned relative the driven element and disposed upon a conductive reflector element. A resonant circuit is thus provided and includes the driven element, reflector element, and pair of LC trap structures.
In a preferred form, the cellular telephone/PCS device antenna assembly is positioned within an antenna housing in the interior of a vehicle. A desirable feature of an interior mounted antenna assembly as compared to an exterior mounted antenna is the lack of a vehicle surface aperture for passing the coax feed line to the exterior environment. The antenna assembly also provides a disguised antenna which is hidden to prevent unwanted recognition, making the antenna assembly less visible and accessible to thieves and vandals. Since the antenna assembly is encased in a protective housing, it cannot easily be bent, broke, or otherwise damaged. Advantageously, the in-vehicle antenna assembly is not normally in contact with or adversely effected by external weather conditions, e.g. ice, snow, sleet, or rain.
The antenna assembly is also less obstructive to the occupants of the vehicle and provides a greater unimpaired range of vision for the driver. In one preferred embodiment, the antenna assembly may reside within a separate housing which may be dash-mounted or rear-deck mounted. In another embodiment, the antenna assembly may be positioned within an upper rear brake light assembly of the vehicle. In yet another embodiment, the in-vehicle antenna assembly is positioned within a rear view mirror assembly.
Yet another object of the invention provides an antenna structure partially formed from a metallic stamping. Elements of the antenna structure may be efficiently defined by reshaped regions of a conductive planar panel through a stamping or related process. These and other objects, features and advantages of the present invention will become apparent to one skilled in the art upon analysis of the following detailed description in view of the drawings.
REFERENCES:
patent: 3725938 (1973-04-01), Black et al.
patent: 4010475 (1977-03-01), James
patent: 4494122 (1985-01-01), Garay et al.
patent: 5767807 (1998-06-01), Pritchett
patent: 5767812 (1998-06-01), Basciano et al.
patent: 5999140 (1999-12-01), Johnson
Klos John F.
Larkin Hoffman Daly & Lindgren Ltd.
Nguyen Hoang
RangeStar Wireless, Inc.
Wong Don
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