The present invention generally pertains to an accessory for enhancing the range and/or directionality of a wireless device in a wireless network, and more specifically, pertains to an accessory that has an electromagnetic reflective surface removably positioned adjacent to an antenna of a wireless device to provide improved range/directionality relative to other wireless devices in the network.
There are several techniques that can be used to increase the range of a wireless transmitter/receiver. If the wireless device has a removable antenna, the antenna can be changed to one that provides greater gain and directionality. However, many wireless devices have a fixed antenna that is not designed to be readily removed and replaced, or include an internal antenna, or cannot be replaced for other reasons. While the power of the signals transmitted and received might be increased by changing the RF amplifier or power supply used in the device, to achieve the desired result, it is generally not practical to modify the circuit design and power supply of a wireless device to improve its range.
Even if the antenna of a wireless device can readily be changed, there are several disadvantages to using a replacement antenna with greater gain to achieve a desired range and directionality. First, the antenna connector that facilitates use of a replacement antenna adds cost to a wireless device, which increases the initial purchase price of the device. In addition, it is often desirable to use two antennas on a wireless device to provide antenna diversity, which improves the reception capabilities of the device. But, the benefits of antenna diversity are reduced if the wireless device includes an external and internal antenna, and only the external antenna is replaced. Also, replacement antennas can be relatively expensive to purchase.
Accordingly, it would be preferable to develop an alternative approach to achieve increased range and/or directionality without replacing the existing antenna on a wireless device. Any solution to this problem should not increase the cost of the wireless device as it is normally sold, since some users may not need the increased range and directionality. Also, a solution to this problem should not adversely affect antenna diversity.
The reduction in signal strength caused by intervening walls or distance between devices communicating in a wireless system can be addressed by providing a suitable reflector that is disposed at an appropriate spacing from an existing antenna system on selected wireless devices so that the reflected signal from the reflector reinforces the signal strength of the wireless signals transmitted and received by the supplied antenna system of the device. A reflector can increase the signal strength of a signal transmitted or received by a simple antenna, such as a post antenna, and also improve the directionality of the transmitted and received signals relative to the antenna system. Different shape and size reflectors can be employed in this accessory device, depending upon the type of existing antenna system with which the accessory will be used and the intended goal of the accessory.
The accessory includes a support adapted to be removably coupled to a wireless device at a predefined distance from an existing antenna system. A conductive material disposed on the support extends over an area of sufficient size, so that when the accessory is disposed adjacent to the existing antenna system of the wireless device, the conductive surface serves as a reflector for wireless signals. The reflector thereby enhances at least one of a range and a directionality of wireless signals transmitted or received by the wireless device, without requiring that the antenna system supplied with the device be replaced.
The conductive material defines a surface extending over the support, and this surface is generally planar. Alternatively, the surface can be curved in a shape selected so that when the accessory is disposed at the predefined distance from the existing antenna system, wireless signals are directed in a desired pattern by the conductive material. In one embodiment, the surface defined by the conductive material extends over an area sufficient in size so that the surface is disposed at the predefined distance from a plurality of spaced-apart antennas comprising an existing antenna system of a wireless device.
In another embodiment, the accessory further includes a clip that is sized and shaped so as to couple the accessory to a post antenna of the wireless device. Optionally, the accessory includes a director disposed on a side of the clip opposite from the support and sized and shaped to direct a wireless signal produced or received by a wireless device.
Yet another embodiment includes a base that is sized and shaped so as to couple the accessory to a housing of a wireless device. As another option, the accessory can include means for hanging the accessory and a wireless device on a vertical surface, such as brackets on the reflector or one or more orifices extending through the reflector for accepting threaded fasteners that connect the reflector to a vertical surface.
The predefined distance between the reflector and the existing antenna is preferably about a quarter wavelength of the wireless signal produced or received by the wireless device, but may vary due to the reflecting structure used.
Another aspect of the present invention is directed to a method for increasing at least one of a range of the antenna on a wireless device and a directionality of a wireless device. The method includes steps that are generally consistent with the functions implemented by the components of the accessory described above.
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
Exemplary Wireless Network Illustrating Utility of Present Invention
An exemplary wireless network 10 in
Most wireless networks include at least one wireless access point or base station. Thus, wireless network 10 includes a wireless access point 12 that is provided with an accessory 20 (shown schematically) for improving the range and directional characteristics of the wireless signal transmitted and received by wireless access point 12 in accord with the present invention. Wireless access point 12 is coupled to a cable modem or digital subscriber line (DSL) interface 14, which in turn is connected respectively either to a cable network or a DSL enabled telephone line 16 that provides an Internet connection conveying broadband signals. Also, wireless access point 12 may be directly coupled to a client computing device 18 through a universal serial bus (USB) interface, or other suitable connections such as an Ethernet port.
Wireless access point 12 communicates with two client computing devices having a wireless interface 24 and 26. The wireless interface will typically comprise either a wireless interface card that connects to a data bus in a computing device, or a PCMCIA (Personal Computer Memory Card International Association) card of the type used in a portable computing device. These client computing devices are coupled to the Internet using wireless signals that are transmitted to and from wireless access point 12.
Client computing devices with wireless interfaces 24 and 26 are disposed within a region 32. Within region 32, the strength of the wireless signals transmitted and received by wireless access point 12 are sufficient to readily communicate with these two client computing devices using only the antenna system included with wireless access point 12. However, a client computing device with wireless interface 30 is disposed within a region 34 that has different reception and transmission characteristics than region 32. A primary cause of the different reception and transmission characteristics within region 34 is a physical obstruction 28 that is interposed between client computing device 30 and wireless access point 12. However, even without the physical obstruction, client computing device 30 might simply be disposed at too great a distance to readily communicate with wireless access point 12, given the specific limitations of the wireless interface and/or wireless access point and the frequency being employed.
Physical obstruction 28 may comprise a wall, or a plurality of walls or ceilings or other internal building structures that reduce the signal strength of wireless signals propagating through the structure in which wireless network 10 is installed. An accessory 20 in accord with the present invention is coupled to wireless access point 12 and is specifically intended to address this problem by providing enhanced directionality and extending the range of the wireless signals propagating between wireless access point 12 and client computing device 30, so that they can readily communicate with each other. Although accessory 20 is only shown coupled to wireless access point 20 it might also optionally be coupled to the wireless interface of client computing device 30. Or as a further alternative, accessory 20 might be fitted only to the wireless interface on client computing device 30 (but not on wireless access point 12). Since the accessory improves the signal strength and directionality of both transmit and receive signals, it only needs to be used on one of the two wireless devices that are communicating with each other, since both devices will benefit from the enhanced signal strength and directionality provided by the accessory.
One possible disadvantage of using accessory 20 with wireless access point 12 instead of client computing device 30 is that the signal strength is thereby reduced on the opposite side of the accessory. Thus, if another client computing device with wireless interface were disposed on the opposite side of wireless access point 12, the signal level on the opposite side might be to low to enable communication with wireless access point 12. Using the omni-directional antenna system originally supplied with wireless access point 12 would be preferable in this situation, since the signal strength would then be more uniform in all directions around wireless access point 12.
Embodiments of Adaptors for Improving Signal Strength/Directionality
Most laptops and other portable devices employ either built-in wireless interfaces or use PCMCIA wireless interface cards that may not have a post antenna. Wireless interface cards that are designed to plug into the data bus of a conventional personal computer typically include external post antennas that are either fixed or able to rotate about one or more axes. The present invention can clearly be used with any antenna system that includes a post, but in other embodiments, can be used with antenna systems that are either completely or partly internal.
As more clearly shown in
Although arm 52 is generally aligned with a longitudinal axis of wireless LAN base station 42 in the illustrations shown in
If wireless LAN base station 42 includes an internal antenna 68, as shown in
A further alternative accessory 60″ is shown in
Turning now to
Yet another approach for increasing the directionality of the accessory in accord with the present invention is illustrated in
For providing greater dispersion of a wireless signal in a general direction, a convex surface might also be used for the reflector instead of a concave surface. Accordingly, it is not intended that the shapes used for the reflector and conductive layer in any way be limited to the examples illustrated in the drawings.
Although the present invention has been described in connection with the preferred form of practicing it and modifications thereto, those of ordinary skill in the art will understand that many other modifications can be made thereto within the scope of the claims that follow. Accordingly, it is not intended that the scope of the present invention in any way be limited by the above description, but instead be determined entirely by reference to the claims that follow.
Number | Name | Date | Kind |
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3742513 | Ehrenspeck | Jun 1973 | A |
5539419 | Ogawa et al. | Jul 1996 | A |
6208300 | Johnson | Mar 2001 | B1 |
6816120 | Kuramoto | Nov 2004 | B2 |
Number | Date | Country | |
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20050026655 A1 | Feb 2005 | US |