Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-01-25
2001-10-09
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S719000, C343S846000, C343S850000
Reexamination Certificate
active
06300907
ABSTRACT:
TECHNICAL FIELD
The invention relates to utility meter transmitter assemblies located in subsurface pit enclosures.
DESCRIPTION OF THE BACKGROUND ART
In moderate climate zones, utility meters are located in subsurface enclosures in areas adjacent to residences or other dwellings. Such enclosures are commonly referred to as “pits.” An example of such an enclosure is illustrated in Cerny et al., U.S. Pat. No. 5,298,894.
As further disclosed in Cerny et al., a radio frequency (RF) transmitter may be situated in an assembly which is mounted or otherwise disposed in the pit enclosure. Such a radio frequency transmitter transmits signals representing meter consumption data to a mobile collection unit which may be carried in a vehicle or which may be carried by a person. Radio frequency transmitters may also be used to transmit signals from such a pit enclosure in a network with stationary collection units at predetermined locations. In this type of system, it has become necessary to provide transmitters and antennae with greater power and greater range than in prior art equipment.
Examples of prior art transmitters and antennae are disclosed in Cerny et al., U.S. Pat. No. 5,298,894, and Bloss et al., U.S. Pat. No. 5,877,703. Cerny et al. discloses that the antenna assembly can be separate from, or integrated with, the transmitter assembly.
It is also desirable to make the assemblies which are located in meter pits compact in size, low in cost of manufacture, durable and easy to install and service.
SUMMARY OF THE INVENTION
The invention relates to an antenna assembly for subsurface utility metering equipment. The assembly has a wire which acts as an inductor and which is connected in cascade with a thin, disk-shaped capacitor to provide an LC circuit of controllable impedance.
The antenna assembly more particularly includes a first planar conductor forming a ground plane and having an aperture therein; a dielectric material disposed over said first planar conductor; and a second planar conductor disposed over said dielectric material and having an area which defines a capacitor that includes the second planar member, a portion of dielectric material lying below said second planar conductor and a portion of the ground plane lying below said second planar conductor. A radiating antenna element is disposed in a plane above and generally parallel to the capacitor and separated from the capacitor by a space. The assembly further includes a connector having a ground portion electrically connected to the ground plane conductor, and a substantially rigid wire conductor extending from a signal portion of the electrical connector, through the aperture in the ground plane, for electrical connection to the second planar conductor, and then extending further and through the space to electrically connect to the antenna element.
The substantially rigid conductor is selected to provide an inductance, and the capacitor is selected to provide a capacitance which when cascaded with the inductance provides an impedance for adjustment to an output impedance of the transmitter.
The invention is provided in at least two embodiments having different levels of integration. The capacitive element is advantageously comprised of a circuit board material having two copper or copper alloy conductors and layer of dielectric material in between the two conductors.
In a preferred embodiment of the invention, a diameter of the antenna element is sized such that the antenna operates in the resonant mode. The ground plane, like the antenna element, is also a radial transmission line and has a diameter such that the ground plane operates in an antiresonant mode, in which a voltage minimum occurs at its periphery.
The assembly is enclosed in a housing of plastic insulating material having a cover and a base portion of a construction to be more particularly described below.
Other objects and advantages of the invention, besides those discussed above, will be apparent to those of ordinary skill in the art from the description of the preferred embodiments which follow. In the description, reference is made to the accompanying drawings, which form a part hereof, and which illustrate examples of the invention. Such examples, however, are not exhaustive of the various embodiments of the invention, and therefore, reference is made to the claims which follow the description for determining the scope of the invention.
REFERENCES:
patent: 4070676 (1978-01-01), Sanford
patent: 4401988 (1983-08-01), Kaloi
patent: 4835540 (1989-05-01), Haruyama et al.
patent: 5270704 (1993-12-01), Quintana et al.
patent: 5298894 (1994-03-01), Cerny et al.
patent: 5416475 (1995-05-01), Tolbert et al.
patent: 5519387 (1996-05-01), Besier et al.
patent: 5583492 (1996-12-01), Nakanishi et al.
patent: 5621419 (1997-04-01), Meek et al.
patent: 5703601 (1997-12-01), Nalbandian et al.
patent: 5825303 (1998-10-01), Bloss, Jr. et al.
patent: 5877703 (1999-03-01), Bloss, Jr. et al.
patent: 6166692 (2000-12-01), Nalbandian et al.
Glissman John
Jensen Richard
Lazar Mark
Lee Tienchu
Marshall Noel
Badger Meter Inc.
Le Hoang-anh
Nguyen Hoang
Quarles & Brady LLP
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