Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-10-09
2002-04-09
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000, C343S846000
Reexamination Certificate
active
06369761
ABSTRACT:
BACKGROUND OF THE INVENTION
Ever expanding mobile communications require increasingly sophisticated antenna technology. The need for antennas capable of operating at multiple bands is continually increasing. Two options exist to meet this need—multiple antennas or multiple-band antennas. Several multiple-band antennas have been developed, but all suffer drawbacks.
The quarter-wave monopole is currently the most popular mobile antenna. A monopole can be a dual-band antenna if it includes a coil or “choke” along its length. The monopole antenna with the choke provides dual-band functionality. However, the monopole antenna has drawbacks. First, it is aesthetically undesirable. Second, because it must extend from an exterior portion of the car, it is subject to damage and theft, as well as being a nuisance in going through carwashes.
Another dual-band antenna is the “Andrew” antenna, which has a “bow tie” configuration. This antenna also has drawbacks. First, it must be mounted inside the car, which reduces its performance well below the performance of a quarter-wave monopole. Second, it does not possess the omnidirectionality required for mobile communication applications.
The planar inverted F antenna (also know as a U-shape or an L-shape) is a single-band, low-profile antenna that provides performance comparable to a quarter-wave monopole. The low profile enables the antenna to be quite unobtrusive, even on a vehicle exterior. However, to handle multiple bands, multiple single-band antennas must be used.
SUMMARY OF THE INVENTION
The aforementioned problems are overcome in the present invention comprising a dual-band antenna having an extremely low profile and being relatively compact. Specifically, the antenna includes a ground plane and upper and lower planar elements all parallel to one another and spaced from one another. The lower element is connected to the ground plane through a plurality of shorting posts. A probe or lead interconnects the centers of the upper and lower elements to provide an antenna lead. The lower element alone is responsive to a first frequency band (the higher frequency band); and the coupled upper and lower elements are responsive to a second frequency band (the lower frequency band).
The present antenna has an extremely low profile and is highly compact. It is well suited for mounting in a wide variety of locations inside or outside of a vehicle.
These and other objects, advantages, and features of the invention will be more fully understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.
REFERENCES:
patent: 4994820 (1991-02-01), Suzuki et al.
patent: 5003318 (1991-03-01), Berneking et al.
patent: 5291210 (1994-03-01), Nakase
patent: 5307075 (1994-04-01), Huynh
patent: 5703601 (1997-12-01), Nalbandian et al.
patent: 5767810 (1998-06-01), Hagiwara et al.
patent: 5917450 (1999-06-01), Tsunekawa et al.
patent: 6239750 (2001-05-01), Snygg
patent: 2709878 (1995-03-01), None
Choon Sae Lee & Vahakn Nalbandian, Planar Circularly Polarized Microstrip Antenna with a Single Feed 47 IEEE Transactions on Antennas and Propagation 1005 (Jun. 1999).
Fuchs Andreas Dirk
Lindackers Ralf
Phillips Daniel R.
Thiam Cheikh T.
Nguyen Hoang
RecepTec L.L.C.
Warner & Norcross & Judd LLP
Wong Don
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