Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2000-10-27
2002-07-23
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S7000MS, C343S767000
Reexamination Certificate
active
06424300
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to antennas, and more particularly to antennas used with wireless communications devices. Radiotelephones generally refer to communications terminals which provide a wireless communications link to one or more other communications terminals. Radiotelephones may be used in a variety of different applications, including cellular telephone, land-mobile (e.g., police and fire departments), and satellite communications systems. Radiotelephones typically include an antenna for transmitting and/or receiving wireless communications signals. Historically, monopole and dipole antennas have been employed in various radiotelephone applications, due to their simplicity, wideband response, broad radiation pattern, and low cost.
However, radiotelephones and other wireless communications devices are undergoing miniaturization. Indeed, many contemporary radiotelephones are less than 11 centimeters in length. As a result, there is increasing interest in small antennas that can be utilized as internally-mounted antennas for radiotelephones.
It is also becoming desirable for radiotelephones to be able to operate within multiple frequency bands in order to utilize more than one communications system. For example, GSM (Global System for Mobile) is a digital mobile telephone system that operates from 880 MHz to 960 MHz. DCS (Digital Communications System) is a digital mobile telephone system that operates from 1710 MHz to 1880 MHz. The frequency bands allocated for cellular AMPS (Advanced Mobile Phone Service) and D-AMPS (Digital Advanced Mobile Phone Service) in North America are 824-894 MHz and 1850-1990 MHz, respectively. Since there are two different frequency bands for these systems, radiotelephone service subscribers who travel over service areas employing different frequency bands may need two separate antennas.
There is also a growing trend towards development of radiotelephones which perform multiple functions. For instance, radiotelephones may incorporate Global Positioning System (GPS) technology or Bluetooth™ wireless technology. GPS is a constellation of spaced-apart satellites that orbit the Earth and make it possible for people with ground receivers to pinpoint their geographic location. Bluetooth technology provides a universal radio interface in the 2.45 GHz frequency band that enables portable electronic devices to connect and communicate wirelessly via short-range ad hoc networks. Radiotelephones incorporating these technologies may require additional antennas tuned for the particular frequencies of GPS and Bluetooth.
Thus, as noted in U.S. patent application Ser. No. 09/193,587, entitled Portable Radiotelephones Including Patch Antennas, to William O. Camp, Jr., assigned to the assignee of the present invention, the disclosure of which is hereby incorporated herein by reference, radiotelephones including GPS receivers have typically used an additional antenna to provide GPS reception. For example, quadrafilar helix antennas extending from the radiotelephone body have been used. The size constraints on these antennas, however, may reduce the gain available using quadrafilar helix antennas. Moreover, these antennas may be oriented at less than ideal angles and/or may be too close to the user's body when used during telephone communications further reducing gain. Accordingly, there continues to exist a need in the art for improved antennas for GPS receivers incorporated into radiotelephones.
Recently, the Federal Communications Commission (FCC) has promulgated rules requiring that all cell phones be able to transmit their location during a 911 emergency call. As a result, when a user makes an emergency (911) call, the cell phone can be used to precisely determine the user's location and transmit that location as a part of the emergency (911) call. The FCC approach is defined as Enhanced 911 (E911)Call Completion. The FCC requirements for E911 are described in FCC Document No. 94-102 (available at www.fcc.gov/e911/). One way the FCC requirements for E911 may be satisfied is by providing a cell phone with a separate GPS antenna.
In the few cases that a GPS function has been included in a cell phone product, the GPS antenna has typically been a patch antenna. For example, see U.S. patent application Ser. No. 09/193,587, entitled Portable Radiotelephones Including Patch Antennas, to William O. Camp, Jr., wherein a large GPS patch antenna is located on the front face of a cell phone. Although this configuration may enhance isolation, it may also undesirably disable the GPS function when the cell phone is in a normal talk position. Moreover, large patch antennas may be undesirable in today's shrinking cell phones. In addition, externally mounted GPS antennas may be aesthetically undesirable.
A GPS antenna and a primary antenna within a wireless communicator, such as a cell phone, may be in close proximity. Interference and/or coupling between the two antennas may degrade the performance of both antennas. For example, a circuit coupled to one antenna may absorb power coupled to it from the other antenna thereby reducing efficiency of the other antenna. Alternately, a circuit coupled to one antenna may reflect power coupled from the other antenna thereby distorting a radiation pattern for the adjacent antenna.
As such, there is a need for GPS antennas that are small in size, that are inexpensive to manufacture, and that can be isolated from other antennas within a wireless communicator, such as a cell phone.
Notch antennas are well known antenna structures. Notch antennas have a radiation pattern which allows for uniform reception in all directions except for one or more relatively small angular regions where there is a null having a relatively steep slope. Notch antennas may be formed by etching a single side of a unitary metallically clad dielectric sheet or electrodeposited film using conventional photoresist-etching techniques.
FIG. 3A
shows a perspective view of a conventional hand-held two way radio shown partially cut away to illustrate the location of a notch antenna.
FIG. 3B
illustrates a more detailed perspective view of the conventional notch antenna of FIG.
3
A. In particular, U.S. Pat. No. 4,723,305 to Phillips et al. discloses an improved antenna configuration for a fully duplex portable radiotelephone that is normally operated in the nearly horizontal position next to the user's ear and mouth. A notch antenna is provided in the bottom portion of the portable radio transceiver parallel to the major longitudinal axis of the housing. Phillips et al. suggest that the notch
80
aperture is cut in the conductive radio housing
78
at a transverse angle to the major face plane of the radiotelephone to form a notch antenna which radiates predominantly vertically polarized E-field waves when the transceiver is positioned such that the major longitudinal axis of the radio is approximately horizontal. U.S. Pat. No. 4,723,305 also discloses that the notch
80
is positioned in the bottom portion
20
of conductive housing
78
such that a plane passing through the notch is perpendicular to the major surface plane of the housing (which is parallel to the X-Y plane). Significantly, the notch
80
is cut in the bottom of the case such that the antenna is located under an operator's hand. The other ends of coaxial cables
86
,
88
are attached to radio circuitry
90
as shown.
SUMMARY OF THE INVENTION
In view of the above discussion, notch antennas that can be internally incorporated into wireless communicators and that are functional in a variety of orientations are provided. As used throughout, a “wireless communicator” may refer to analog and digital radiotelephones, multiple mode radiotelephones, high function Personal Communication Systems (PCS) devices that may include large displays, scanners, full size keyboards and the like, and laptop, palmtop and pervasive computing devices that include wireless communications capabilities.
According to first embodiments of the present invention, an
Holshouser Howard E.
Sanford Gary George
Chen Shih-Chao
Le Hoang-anh
Telefonaktiebolaget L.M. Ericsson
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