Communications: radio wave antennas – Antennas – Loop type
Reexamination Certificate
1999-07-21
2001-02-13
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Loop type
C343S741000, C343S846000, C343S847000
Reexamination Certificate
active
06188371
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally pertains to antennas and is particularly directed to low-profile antennas.
Low-profile antennas are used on aircraft and various earth-bound vehicles, including trains, motor vehicles and ships. One type of low-profile antenna is a marker-beacon antenna, such as described by R. A. Burberry, “VHF and UHF Antennas”, Peter Peregnus, Ltd., UK, 1992, p. 161. Other types of low-profile antennas are described in U.S. Pat. No. 5,880,697 to McCarrick et al. and U.S. Pat. No. 4,862,181 to Ponce De Leon et al. Each of these different types of low-profile antennas includes an elongated radiator element configured and disposed in relation to a ground plane to define a vertical loop when the ground plane is horizontally disposed, with a substantial broad segment of the radiator element being parallel to the ground-plane element, with one end of the radiator element being connected to the ground-plane element and with another end of the radiator element being capacitively coupled to the ground-plane element.
SUMMARY OF THE INVENTION
The present invention provides a low-profile antenna of simple construction that may be operated within an adjustable range of frequencies.
An antenna according to the present invention comprises a ground-plane element defining a ground plane; an elongated radiator element configured and disposed in relation to the ground plane to define a vertical loop when the ground plane is horizontally disposed, with a substantial broad segment of the radiator element being parallel to the ground plane, with one end of the radiator element being connected to the ground-plane element and with another end of the radiator element being capacitively coupled to the ground-plane element; a dielectric spacing element disposed between the other end of the radiator element and the ground-plane element for capacitively coupling the radiator element to the ground-plane element; and a conductive-material layer contacting the other end of the radiator element between the other end of the radiator element and the dielectric spacing element with an exposed portion of the conductive-material layer extending from beneath the other end of the radiator element for enabling said capacitive coupling to be adjusted by removing at least some of the exposed portion of the conductive-material layer; wherein said adjustable capacitive coupling and the dimensions and configuration of the radiator element are such as to enable the radiator element to resonate within an adjustable band of frequencies within a predetermined range of frequencies. In the preferred embodiment, the exposed portion of the conductive-material layer includes a plurality of tabs that can be removed selectively to adjust said capacitive coupling.
In one aspect a low-profile antenna includes a tuning circuit that is coupled to the radiator element for selectively enabling the antenna to transmit signals at a first frequency within said band or to receive signals at a second frequency within said band.
Additional aspects and features of the present invention are described with reference to the detailed description of the preferred embodiments.
REFERENCES:
patent: 4827266 (1989-05-01), Sato et al.
patent: 4862181 (1989-08-01), Ponce De Leon et al.
patent: 5764190 (1998-06-01), Murch et al.
patent: 5767810 (1998-06-01), Hagirawa et al.
patent: 5880697 (1999-03-01), McCarrick et al.
patent: 6002367 (1999-12-01), Engblom et al.
Burberry, “VHF and UHF Antennas” Peter Peregnus, Ltd. UK, 1992, p. 161.
Johnson, “Antenna Engineering Handbook” 3rd. ed., Georgia Institute of Technology, 1993, pp. 27-21, 37-18/19.
Li Kevin
Lin Leon Chia-Liang
Seay Thomas Stanley
Wixom Brian Louis
Callan Edward W.
Nguyen Hoang
Quake Wireless, Inc.
Wong Don
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