Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
1999-08-16
2001-04-10
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C348S700000
Reexamination Certificate
active
06215447
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to antenna assemblies for hand held radio frequency transmitters or receivers, and more particularly to antenna assemblies for communication devices such as cellular telephones, PCS devices, and the like.
2. Description of the Related Art
Various antennas have been proposed and implemented for radio frequency communication devices such as cellular phones, PCS telephones and the like. Antennas have also been proposed and developed for other applications, for example, U.S. Pat. No. 5,677,698 shows a slot antenna arrangement for portable personal computers. Prior antennas for radio frequency transceivers for telecommunication devices such as cellular telephones and PCS devices have had significant limitations including limited signal range, limited directionality, significant radio frequency radiation output to the user, significant multipath interference, and other related performance limitations.
Accordingly, it is the primary object of this invention to provide an improved antenna for communication devices including hand-held radio frequency transceivers such as cellular phones and PCS devices with improved directionality, broadband input impedance, increased signal strength, and increased battery life. The present invention reduces radio frequency radiation incident to the user's body and reduces the physical size requirements for a directional antenna used on communication devices. Other benefits include a reduction in multipath interference, an increased front-to-back ratio, and improved peak gain. The antenna assembly of the present invention may be integrated into the housing of a cellular transceiver, for example, at the rear portion of a cellular telephone, and is accordingly less susceptible to damage during normal operation.
In general, wireless communication devices, and hand held cellular telephones in particular, use external whip antennas which radiate nominally omnidirectionally. Minimal reduction in transmitted RF energy toward the user's head is provided. As a consequence, typical specific absorption rates (SAR) values of 2.7 mw/g at 0.5 watts input are realized. The external whip antenna is also susceptible to damage and misalignment. Gain of the whip antenna is typically in the range of −5 to +1.5 dBi.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
SUMMARY OF THE INVENTION
To achieve the foregoing objects, and in accordance with the purpose of the invention as embodied and broadly described herein, a multiple element directive antenna assembly for a hand-held radio frequency communication device, such as a cellular telephone or PCS device, is provided. The antenna assembly has a configured active radiating conductor element disposed relative to a conductive ground plane element. A dielectric spacing member may be provided to communicatively couple the active radiating conductor element to the ground plane. The conductive ground plane member may be provided by a printed circuit board or other conductive surface of the hand-held radio frequency transceiver. The multiple-element directive antenna allows for improved directionality and reduced user exposure to radio frequency radiation.
The antenna assembly according to the present invention may be used in wireless communication device such as a cellular telephone or PCS devices where a low physical profile antenna is desired. The antennas of the present invention are particularly suited to receive and radiate electromagnetic energy in the 1850-1990 MHz band. The disclosed antenna offers a rugged, low cost antenna assembly having improved physical parameters while providing superior conformal capability for a handset chassis. Importantly, the overall volume occupied by the present antenna assembly can be held to a minimum. Due to their relative size and conformability, such antenna is preferably housed within an interior portion of the communication device, or on a back chassis surface of the device.
The antenna assembly according to the present invention may operate proximate a ground plane element of a communication device and provide 0-6 dBi gain and 3-18 dB front-to-back directivity, over 2:1 VSWR bandwidths of 8% with linear polarization. Significant improvements include: a reduced overall size relative to known antenna assemblies having similar performance characteristics; the ability to incorporate the antenna within a communication device housing without external appendages; a provision of an interior region within the conductor element and the printed wiring board in which componentry of the communication device may be disposed; and a reduction in the RF energy directed toward a user's head during operation of a hand-held communication device. The present invention provides a substantially smaller and more compact antenna assembly relative to known antenna assemblies having similar gain and directivity characteristics.
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Clinger James
Klos John F.
Larkin Hoffman Daly & Lindgren Ltd.
RangeStar Wireless, Inc.
Wong Don
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