Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2001-04-16
2002-06-18
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S795000, C343S850000
Reexamination Certificate
active
06407710
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to antennas and antenna structures for hand-held, portable, or fixed wireless communications devices (WCD), such as cellular telephones, data devices, and GPS receivers. More particularly, the invention relates to an asymmetrical dipole antenna that includes a short planar conductor (ground plane) portion, a resonator portion and a matching network portion. In one embodiment, the antenna is adaptable to fit inside a housing of a WCD for mechanical robustness. An antenna according to the present invention may be used for transmitting, receiving, or for transmitting and receiving.
DESCRIPTION OF RELATED ART
There exists a need for an improved antenna assembly that provides a single and/or dual band response and which can be readily incorporated into a small wireless communications device (WCD). Size restrictions continue to be imposed on the radio components used in products such as portable telephones, personal digital assistants, pagers, etc. For wireless communications devices requiring a dual band response the problem is further complicated. Positioning the antenna assembly within the WCD remains critical to the overall appearance and performance of the device.
Known wireless communications devices such as hand-held cell phones and PCS devices typically are equipped with an external wire antenna (whip), which may be fixed or telescoping. Such antennas are inconvenient and susceptible to damage or breakage. The overall size of the wire antenna is relatively large in order to provide optimum signal characteristics. Furthermore, a dedicated mounting means and location for the wire antenna are required to be fixed relatively early in the engineering process. Several other antenna assemblies are known, including:
Quarter wave straight wire antenna
A quarter wave straight wire antenna is a ¼ wavelength external antenna element, which operates as one side of a half-wave dipole. The other side of the dipole is provided by the ground traces of the transceiver's printed wiring board (PWB). The external ¼ wave element may be installed permanently at the top of the transceiver housing or may be threaded into place. The ¼ wave element may also be telescopically received into the transceiver housing to minimize size. The ¼ wave straight wire adds from 3-6 inches to the overall length of an operating transceiver.
Coiled quarter wave wire antenna
A coiled quarter wave wire antenna has an external small diameter coil that exhibits ¼ wave resonance, and is fed against the ground traces of the transceiver's PWB to form an asymmetric dipole. The coil may be contained in a molded member protruding from the top of the transceiver housing. A telescoping ¼ wave straight wire may also pass through the coil, such that the wire and coil are both connected when the wire is extended, and just the coil is connected when the wire is telescoped down. The transceiver overall length is typically increased by ¾-1 inch by the coil.
Planar Inverted F Antenna (PIFA)
PIFA (Planar Inverted F Antenna) antennas have been used to provide a linear polarization and an omnidirectional pattern in free space, in one plane. A PIFA antenna has an external conducting plate which exhibits ¼ wave resonance, and is fed against the ground traces of the PWB of a transceiver to form an asymmetric dipole. The plate is usually installed on the back panel or side panel of a transceiver and adds to the overall volume of the device.
Patch
Patch antennas have been used to provide either a linear polarization or a circular polarization and a near-hemispherical pattern in free space. An antenna including a planar dielectric material having a resonant structure on one major surface of the dielectric and a second ground plane structure disposed on the opposite major surface. A conductive post may electrically couple (through the dielectric) the resonant structure to a coaxial feedline.
Additionally, there have been numerous efforts in the past to provide an antenna inside a portable radio communication device. Such efforts have sought at least to reduce the need to have an external whip antenna because of the inconvenience of handling and carrying such a unit with the external antenna extended.
Various configurations of driven or driven and parasitic elements located on one side and at one end of a larger planar conductor are known to provide gain proximate that of a dipole (+2.1 dBi), a unidirectional pattern, and linear polarization. The planar conductor's major dimension has been known to be greater than that required for the antenna of the present invention, for operation at a particular frequency range.
SUMMARY OF THE INVENTION
In view of the above-mentioned limitations of the prior art antennas, it is an object of the present invention to provide an antenna for use with a portable wireless communications device. It is another object of the invention to provide an antenna unit which is lightweight, compact, highly reliable, and efficiently produced.
The present invention replaces the external wire antenna of a wireless communication device with a resonator element which is disposed within the housing of a wireless device and closely-spaced to the printed wiring board (PWB) and signal port of the wireless device. Electrical connection to the wireless device's PWB may be achieved through automated production equipment, resulting in cost effective assembly and production.
It is an object of the present invention to provide an antenna assembly which can resolve the above shortcomings of conventional antennas. Additional objects of the present invention include: the elimination of the external antenna and its attendant faults such as susceptibility to breakage and impact on overall length of the transceiver; the provision of an internal antenna that can easily fit inside the housing of a wireless transceiver such as a cell phone, with minimal impact on its length and volume; the provision of a cost effective antenna for a wireless transceiver, having electrical performance comparable to existing antenna types; and, the reduction in SAR (specific absorption rate) of the antenna assembly, as the antenna exhibits reduced transmit field strength in the direction of the user's ear for hand held transceivers such as a cellular telephone, when compared to the field strength associated with an external wire type antenna system.
Another object of the present invention is the provision of an antenna assembly which is extremely compact in size relative to existing antenna assemblies. The antenna assembly may be incorporated internally within a wireless handset. A unique feed system with a matching component is employed to couple the antenna to the RF port of the wireless device. Beneficially, the antenna assembly may be handled and soldered like any other SMD electronic component. Because the antenna is small, the danger of damage is minimized as there are no external projections out of the WCD's housing. Additionally, portions of the antenna assembly may be disposed away from the printed wiring board and components thereof, allowing components to be disposed between the antenna assembly and the printed wiring board (PWB).
Another object of the present invention is an antenna assembly providing substantially improved electrical performance versus volume ratio, and electrical performance versus cost as compared to known antenna assemblies. In a preferred embodiment, the antenna may exhibit resonant frequency ranges within cell phone and PCS bands, 880-960 MHz and 1710-1880 MHz ranges, respectively.
The present invention provides an antenna having a compact size and able to conform to an available volume in the housing of a wireless transceiver such as a cellular telephone. The antenna assembly may be excited or fed with 50 ohm impedance, which is a known convenient impedance level found at the receiver input/transmitter output of a typical wireless transceiver.
One aspect of the present invention provides an asymmetri
Commens Matthew
Hill Robert
Keilen Donald
McKivergan Patrick
Fulbright & Jaworski L.L.P.
Le Hoang-anh
Tyco Electronics Logistics AG
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