Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2000-08-14
2003-03-11
Wimer, Michael C. (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S7000MS, C343S873000, C455S575100, C455S090300, C455S347000
Reexamination Certificate
active
06531985
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates generally to antenna structures coupled to mobile electronic devices. More specifically, the present invention concerns integrated antennas for portable computers.
2. The Prior State of the Art
Various communication systems are used to allow computers to communicate and exchange data and other types of information. For example, various networks, including Local Area Networks (LAN), Internet, Ethernet and conventional telephone networks, often link computers. These known communication systems, however, usually require the computer to be physically connected to telephone lines, modems or specialized wiring. In some locations, however, it is difficult if not impossible to be physically connected to the communication system. Additionally, these known systems generally cannot be used if the user is traveling or moving to different locations, as is typically the case with a laptop computer.
It is also known to use wireless or cellular telephone systems to connect laptop computers to a communication system. One such application is WLAN, part of the latest technology craze attempting to integrate wireless communication onto portable electronic devices. Another particularly effective application allowing laptop computers to communicate are cellular telephone systems, because the computer does not have to be connected to an existing telephone line. In addition, cellular telephone systems are very useful in connection with portable computers because the cellular communication circuitry can be miniaturized and provided as a component of the computer.
Both of these wireless systems often require specialized antennas. Antenna structures, predominantly used for communication, efficiently transmit and receive electromagnetic energy in the form of radio waves. Antenna structures are used whenever it is impractical, or impossible to use a physical connection, such as a transmission line or wave-guide. In order to get the best performance out of the wireless antenna, the antenna must not be obstructed by anything within its path of radiation.
Antenna design attempts to achieve good impedance matching to the feeding transmission line so as to maximize the available power for radiation. Often the power levels are limited by transmission standards. For example “Bluetooth” wireless technology is a de facto standard, as well as a specification for small-form factor, low-cost, short-range radio links between laptops, phones, and other portable digital devices. One of the present Bluetooth specifications is to limit the transmission range to around 10meters. Bluetooth limits the transmission range by reducing the transmit power to the antenna, thus in order to conform with the Bluetooth standard the maximum available transmit power supplied to the antenna for radiation. Thus, while the antenna is designed to distribute the radiation optimally, it has a limited transmission range due to the supplied transmit power.
Antenna design also attempts to achieve the best compromise between the various constraints imposed on the desired radiation pattern. Optimization of the radiation pattern may include maximizing the radiation in one direction and suppressing it in others. If a specific desired radiation pattern is difficult or impossible to obtain using a single antenna, antenna engineers will often resort to designing arrays of simple antennas. Adjustment of the amplitude and phase of the feed voltages to the various elements in the array, as well as the geometrical arrangement of these elements, often achieves the desired radiation characteristics. Unfortunately, antenna array design is complicated by the mutual interaction between the various elements in the array and the operating environment of the array.
One example of a more difficult operating environment with multiple mutual interacting components that affect the desired radiation patterns is a laptop computer. Different brands of laptop computers use different shielding components for electromagnetic interference (EMI) that affect the antennas quite dramatically from one vendor to another. For example, some laptop computers use conductive materials or fillers, such as exotic conductive plastic material, that interfere with fully integrated antenna arrays in the laptop cases or housing bodies. Of course, the laptop display screen also presents a difficult shielding problem of the radiation pattern depending on where the antenna is located. Furthermore, a user is generally positioned in front of the laptop computer blocking a portion of the receiving area and obstructing the desired radiation pattern. Obstruction by the user is especially important with a low power wireless signal, such as Bluetooth, where signals are easy to block and absorb the radiation pattern.
Additionally, the present marketplace severely restricts the placement of integrated antenna structures on laptop computers due to performance, aesthetic, and reliability concerns. Most notable is the reluctance to place an extended integrated antenna on top of the laptop display screen, where the antenna would be virtually unobstructed out and away from everything. It is believed that this reluctance is due to concerns that the antenna structure would interfere with the LCD display. Another concern is that extended antenna structures are often bent, broken, knocked out of alignment or otherwise damaged. It is known that the repair and replacement of integrated antennas is difficult and costly. In fact, the entire attached display screen assembly is often removed and replaced instead of attempting to repair a portion of the integrated antenna or support structure. Thus, repair or replacement of the integrated antenna on top of the display screen is expensive and time consuming. As previously mentioned, even cellular systems require specialized antennas. Antennas used with cellular communication systems generally include a number of antenna elements, each including a radiating element, which is equal in length to some fraction of the wavelength to be transmitted or received. In order to increase the efficiency of communication, these known antennas must include elements that are separated by a minimum distance and these elements are preferably orientated normal to each other to provide the necessary separation and spatial diversity.
Conventional antennas used to connect a computer to a wireless communication system or cellular telephone is typically placed externally of the computer because of the noise, interference, obstruction and shielding caused by the various components of the computer. In particular, conventional antennas do not function correctly if they are obstructed or shielded by the housing or other structures of the computer.
Conventional antennas are also generally rigid and they protrude a relatively long distance from the body of the computer. These protruding antennas are often large, unwieldy, aesthetically unpleasing and they make the computer difficult to move and transport. In addition, these antennas are often bent, broken, knocked out of alignment or otherwise damaged because they can easily catch or strike foreign objects such as people, walls, doors, etc. Further, these known antennas require a large support structure to secure the antenna to the housing of the computer and this support structure requires a considerable amount of space inside the body of the computer. This space is very valuable, especially in small, portable computers. Additionally, the support structure is often damaged when the antenna is accidentally moved.
It is known that the repair and replacement of conventional antennas and the associated support structure is difficult and costly. In fact, the entire antenna assembly is often removed and replaced instead of attempting to repair a portion of the antenna or support structure. Thus, the repair and replacement of the antenna and/or antenna support structure is expensive and time consuming.
In order to alleviate these problems, known antennas are often remov
Andrus David
Jones Jeffrey L.
Ostermiller Dirk
Prestwich Sy
3Com Corporation
Wimer Michael C.
Workman & Nydegger & Seeley
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