Communications: radio wave antennas – Antennas – Having electric space discharge device
Reexamination Certificate
2002-06-06
2004-04-27
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Having electric space discharge device
C343S702000
Reexamination Certificate
active
06727856
ABSTRACT:
BACKGROUND
1. Field of the Invention
This invention relates generally to the field of network data services. More particularly, the invention relates to an improved antenna for receiving signals on a wireless device.
2. Description of the Related Art
Antenna systems used in current cell phones and wireless data processing devices are typically comprised of a single straight wire or conducting loop contained within the devices' casing.
FIGS. 1
a
and
1
b
illustrate some of the basic principles associated with antenna theory. The electromagnetic signal received by an antenna
110
is comprised of an electric field vector (E)
120
and a magnetic field vector (H)
130
. The magnetic field vector
130
is perpendicular to the electric field vector
120
. The wave shown in
FIG. 1
a
is said to be “vertically polarized” because the electric field vector is in a vertical orientation. The plane defined by E and H is a plane of energy (measured in, e.g., watts/m
2
) traveling in the direction of Wave propagation (Z)
150
. The transmitter
100
may transmit the wave at various frequencies and using various types of modulation, depending on the particular standards involved (e.g., CDMA, GSM, TDMA, . . . etc).
The antenna
110
configured within the wireless device
105
also transmits and receives an electric field component (E)
121
and a magnetic field component (not shown). For ideal reception, the electric field component
121
of the wireless device's antenna
110
should have the same vertical orientation as the electric field component
120
of the base station signal when the wireless device is in the dominant user position. By contrast, if the electric field
121
of the antenna is perpendicular to the electric field
120
of the base station wave, as illustrated in
FIG. 1
b
, the antenna will not effectively receive the base station signal. Because of this cross-polarized condition, the wireless device will not effectively receive vertically polarized signals from the base station when the wireless device is in a horizontal orientation.
FIGS. 2
a
and
2
b
plot signal strength as a function of the wireless device's rotation. The plot shown in
FIG. 2
a
is associated with rotation arrow
140
shown in
FIG. 1
a
and the plot shown in
FIG. 2
b
is associated with rotation arrow
142
shown in
FIG. 1
b
. If the wireless device is rotated along its vertical axis as indicated by rotation arrow
140
, the vertical component of the antenna's electric field
121
remains in a vertical orientation and signal reception strength is excellent because the electric field vectors of both the base station and the wireless device are aligned. If, however, the device is rotated as indicated by rotation arrow
142
in the horizontal position illustrated in
FIG. 1
b
, then the device's ability to capture energy from the incoming vertically polarized signal is greatly degraded because the electric field of the device's antenna has rotated from a vertical to a horizontal polarization condition.
In sum, present wireless devices are incapable of effectively receiving vertically polarized waves when the wireless device is in a horizontal orientation. Thus, when placed horizontally on a tabletop, the signal strength generally becomes very weak. Adding an additional antenna may strengthen the signal but adds significantly to the cost and complexity of the device.
Moreover, because the antenna
110
is contained within the wireless device
105
the casing must be limited to dielectric materials such as rubber or plastic in the region containing the antenna. In addition, the antenna
110
may consume a significant amount of space within the device
105
which could otherwise be used to make the device more compact and less expensive to manufacture.
Accordingly, what is needed is an antenna system which can effectively transmit and receive a vertically polarized signal when the wireless device is in the vertically oriented dominant user position as well as when the wireless device is placed horizontally on a table. What is also needed is an antenna system which does not consume space within the wireless device or limit the type of material with which the wireless device may be constructed.
SUMMARY
An enclosure for a wireless device is described which may be used as the device's antenna. In one embodiment, the enclosure is designed such that the wireless device is capable of receiving vertically polarized signals in two distinct orthogonal orientations. The antenna is comprised of two charged front and back conducting plates which propagate an omnidirectional vertically polarized electric field used to transmit and receive electromagnetic signals from a first orientation. In addition, in one embodiment, the size of the plates are selected to propagate a second vertically polarized electric field which is used to transmit and receive electromagnetic signals in a second orthogonal orientation.
REFERENCES:
patent: 3736591 (1973-05-01), Rennels et al.
patent: 6195054 (2001-02-01), Washino et al.
patent: 6437745 (2002-08-01), Vaisanen et al.
patent: 6580397 (2003-06-01), Lindell
patent: 6618014 (2003-09-01), Stoiljkovic et al.
patent: 2003/0090422 (2003-05-01), Diament
Blakely , Sokoloff, Taylor & Zafman LLP
Good Technology, Inc.
Ho Tan
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