Communications: radio wave antennas – Antennas – With lumped reactance for loading antenna
Reexamination Certificate
1998-04-07
2001-02-20
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
With lumped reactance for loading antenna
C343S713000, C343S715000
Reexamination Certificate
active
06191747
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to dual band antennas generally and, more particularly, but not by way of limitation, to a novel dual band on-glass antenna which is suitable for simultaneously broadcasting in the PCS and AMPS bands.
BACKGROUND OF THE INVENTION
In a preferred embodiment, the present invention concerns a dual band antenna that can provide simultaneous performance in two separate frequency bands. In a particularly preferred embodiment, the dual band antenna of the present invention provides mobile cellular function in both the AMPS (806-890 MHz) and PCS (1850-1990 MHz) frequency bands. Preferably, the antenna is an on-glass style in which energy is directed along a coaxial cable to an on-glass coupler. The coupler transfers energy through the glass of a vehicle, such as an automobile or a truck, to an external radiating element. The radiating element preferably distributes the energy throughout space in a desired radiation pattern. Preferably, the radiating element is designed to provide omni-directional coverage in azimuth.
Known single band mobile cellular antennas can be classified into two categories based upon the gain that they provide.
As shown in
FIG. 1
, a short, one quarter wavelength stub provides 0 dBd when installed.
As seen in
FIG. 2
, to increase the antenna gain further, a phasing coil is typically added above the quarter wavelength section. A ½ to ⅝
th
wavelength long section of wire is then added above the phasing coil. The phasing coil provides a 180 degree phase shift in the current distribution causing the upper and lower sections radiate constructively. Gain is increased to 3 dBd with this technique.
As illustrated in
FIGS. 3 and 4
, most dual band antennas also fall into two categories.
As seen in
FIG. 3
, the first category of known dual band antennas is based upon radiators that perform like ½ over ¼ wavelength antennas at high frequencies, while performing like ¼ wave antennas at low frequencies. This category of antenna provides 3 dBd gain in the high band but only 0 dB gain in the low band.
As seen in
FIG. 4
, a second category of known dual band antennas is based upon radiators that implement a coaxial choke. These radiators perform in a manner similar to a ¼ wave antenna at high frequencies, while performance at low frequencies is similar to a ½ wave over a ¼ wave antenna. This second category of antennas provides 0 dBd gain at high frequencies and 3 dBd gain at low frequencies.
Both categories of known dual band antennas provide 3 dBd gain in only one of the two frequency bands.
A principal object of the invention is to provide a dual band antenna capable of simultaneously performing in two separate and distinct bands. Another object is to provide a dual band on-glass antenna capable of simultaneously performing in two separate and distinct bands. A further object is to provide a dual band antenna which delivers 3 dBd of gain in two radiating bands simultaneously via a radiating element that electrically or electromagnetically appears as a ½ wavelength over a ¼ wavelength antenna in both bands.
It is yet another object of the present invention to provide a dual band antenna suitable for simultaneous performance in the PCS and AMPS bands.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.
SUMMARY OF THE INVENTION
The present invention achieves the above objects, among others, by providing, in one preferred embodiment, a dual band antenna which includes a radiating element capable of performing simultaneously in first and second distinct bands. The radiating element includes: a one-quarter first wavelength radiating portion which serves as a base; a one-half first wavelength radiating portion for radiating energy in the first band; a first phasing coil joining the one-quarter first wavelength radiating portion to the one-half first wavelength radiating portion, wherein the first phasing coil substantially allows energy in the second band to pass therethrough; a one-half second wavelength radiating portion for radiating energy in the second band; and a second phasing coil joining the one-half second wavelength radiating portion to the one-half first wavelength radiating portion, wherein the second phasing coil substantially prevents energy in the first band from passing therethrough.
The one-quarter first and the one-half first wavelength radiating portions together behave as a one-quarter wavelength radiating sub-element for energy in the second band, whereby the radiating element behaves as a one-half wavelength over one-quarter wavelength radiating element in the second band. The one-half second wavelength radiating portion is substantially inactive in the first band, such that the one-half first and the one-quarter first wavelength radiating portions behave as a one-half wavelength-over-one-quarter wavelength radiating element in the first band.
In a particularly preferred embodiment, the first band substantially corresponds to the PCS band range, and the second band substantially corresponds to the AMPS band range.
In another preferred embodiment, the present invention provides a dual band on-glass antenna for use on a glass pane having an inner surface and an outer surface. The glass pane may be that found, for example, on a windshield of a vehicle. The antenna comprises: an on-glass coupler means for attaching the antenna to the glass pane and for transferring energy through the glass pane, the on-glass coupler means including an inner coupler mounted on the inner surface of the glass pane and an outer coupler mounted on the outer surface of the glass pane; radiating means for simultaneously, spatially distributing energy in first and second frequency bands which is received from the on-glass coupler means, wherein the first and second frequency bands are distinct from each other, the radiating means being attached to the outer coupler and disposed on the outer side of the glass pane; and connection means disposed on the inner side of the glass pane for delivering energy to the on-glass coupler means. In a preferred specific embodiment, the dual band on-glass antenna is adapted to provide a gain of up to approximately 3 dB in both of the bands simultaneously.
The radiating means preferably comprises a radiating element including: a one-quarter first wavelength radiating portion attached to the outer coupler for radiating energy in the first band; a one-half first wavelength radiating portion for radiating energy in the first band; a first phasing coil joining the one-quarter first wavelength radiating portion to the one-half first wavelength radiating portion, wherein the first phasing coil substantially allows energy in the second band to pass therethrough; a one-half second wavelength radiating portion for radiating energy in the second band; and a second phasing coil joining the one-half second wavelength radiating portion to the one-half first wavelength radiating portion, wherein the second phasing coil substantially prevents energy in the first band from passing therethrough.
The one-quarter first and the one-half first wavelength radiating portions together behave as a one-quarter wavelength radiating sub-element for energy in the second band, whereby the radiating element behaves as a one-half wavelength over one-quarter wavelength radiating element in the second band. The one-half second wavelength radiating portion is substantially inactive in the first band, such that the one-half first and the one-quarter first wavelength radiating portions behave as a one-half wavelength over one-quarter wavelength radiating element in the first band.
In a particularly preferred embodiment, the radiating means comprises a radiating element which includes: a one-quarter PCS wavelength radiating portion attached to the outer coupler; a one-half PCS wavelength radiating portion;
Hirschmann Electronics, Inc.
Klauber & Jackson
Phan Tho
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