Low profile sector antenna configuration

An impedance plane has an elongated strip ship. The impedance plane approximates a magnetic conductor within a particular frequency band. A sector antenna is coupled to one side of the impedance plane. The sector antenna has a planar form factor with dimensions contained within the elongated strip. The sector antenna has a radiation pattern in the particular frequency band that is flared out from the impedance plane at a particular angle.

FIELD OF THE INVENTION

The present invention relates to the field of wireless communications. More specifically, the present invention relates to a low profile, sector antenna configuration.

BACKGROUND

Wireless communications are a driving force in the electronics industry. Wireless connections are widely used for computer networking, peripheral devices, and the like. Antennas are an integral part of all wireless communications. The amount of data that a wireless connection can carry, as well as the distance and the coverage of a wireless connection, often depend in large part on the size, type, and configuration of the antenna(s) being used. Larger antennas tend to provide better connectivity, but large antennas can be inconvenient, fragile, and unsightly. Furthermore, the form factors of many electronic devices do not readily accommodate large or fragile antennas.

Notebook computers provide a good example of the design challenges for antennas. Wireless networking is increasingly popular among notebook computer users. Notebook computers, however, are often compact, leaving limited room for an antenna. Durability is also quite important because notebook computers are frequently moved, packed away and pulled out of bags or carrying cases, used in cramped quarters, and the like. External housings are often made of metal to improve durability, but metal can interfere with, or shield, an antenna. This shielding effect makes an internal antenna especially difficult to implement. Attaching an antenna flush against a metal surface can also be problematic. A protruding antenna, on the other hand, can be vulnerable to damage, not to mention unsightly.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, those skilled in the art will understand that the present invention may be practiced without these specific details, that the present invention is not limited to the depicted embodiments, and that the present invention may be practiced in a variety of alternative embodiments. In other instances, well known methods, procedures, components, and circuits have not been described in detail. Parts of the description will be presented using terminology commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. Repeated usage of the phrase “in one embodiment” does not necessarily refer to the same embodiment, although it may.

Embodiments of the present invention combine a strip of magnetic conductor material and a sector antenna into a low profile, sector antenna configuration that can, for example, be mounted flush on a metal surface. Various embodiments of the present invention also arrange a combination of these low profile, sector antennas in different orientations to provide improved, sectorized connectivity.

A sector antenna is directional. In other words, the radiation pattern of a sector antenna is designed to transmit and/or receive a signal in a particular direction, or orientation, with respect to the antenna. Compared to an omni-directional antenna, or a multi-directional antenna, a sector antenna can provide superior connectivity for signals within its radiation pattern.

A Yagi antenna is one example of a sector antenna.FIG. 1illustrates one embodiment of a Yagi antenna170. A number of parallel dipoles110,120, and130are arranged perpendicularly along a common axis140. Dipole120is often called the driven dipole, where a signal enters or leaves the antenna. Dipole110is usually longer than dipole120and is often called the reflector dipole. Dipoles130are often called director dipoles. A Yagi antenna may include one or more director dipoles.

The antenna's radiation pattern150is generally directed along the common axis140, and fans out at a particular angle160. The angle160is often called an azimuth or elevation, depending on how the antenna is oriented. Azimuth usually refers to the angle in a horizontal plane and elevation usually refers to the angle in a vertical plane. The azimuth and elevation angles can be different for a given antenna. In the illustrated embodiment, angle160is over 90 degrees.

A Yagi antenna can be made in a planar form factor with a low profile. For instance, as shown inFIG. 1, the antenna170can be printed in a layer of a printed circuit board (PCB)100. Additional layers of the PCB above and below the antenna can provide a great deal of protection for the antenna in a form factor that is mere millimeters or less in thickness.

FIG. 2illustrates a side view of the Yagi antenna170fromFIG. 1. The radiation pattern150can also be seen in this view as it is generally directed along the length of the antenna. The angle260at which the radiation pattern fans out may be different in this orientation than angle160inFIG. 1.

The magnetic conductor material used in various embodiments of the present invention is an impedance plane that acts as a sort of radio frequency mirror, both altering the direction of the radiation pattern of the sector antenna and providing improved isolation for the antenna. Artificial Magnetic Conductor (AMC) material is a type of magnetic conductor. AMC is usually made from layers of printed circuit board (PCB) material comprising metal patches, vias (holes), and dielectric material, giving it a planar form factor. In some embodiments, the AMC material can have a thickness of 4 millimeters or less.

AMC is designed to approximate a perfect magnetic conductor for signals in at least one particular frequency band. For example, single-band AMC material can approximate a perfect magnetic conductor in one frequency band, and dual-band AMC material can approximate a perfect magnetic conductor in two frequency bands.

FIGS. 3 and 4illustrate one embodiment of a low profile, sector antenna configuration300. Sector antenna320and AMC strip310both have planar form factors. Sector antenna320is mounted flush against AMC310so that the dimensions of sector antenna320fit within the elongated strip of AMC310.

AMC310alters the radiation pattern that sector antenna320would otherwise have. For signals in the appropriate frequency band(s) where AMC310approximates a perfect magnetic conductor, antenna configuration300has a radiation pattern350that is flared up at an angle330. One or both of the fan-out angles360and460(shown inFIG. 4), however, may be largely unaffected by AMC310.

For example, if Yagi antenna170fromFIGS. 1 and 2were used for sector antenna320, the shape of the radiation pattern350would be substantially similar to the shape of radiation pattern150, just redirected from the plane of the PCB by the angle330. In other words, the fan-out angle360, like angle260, would be over 90 degrees.

In the illustrated embodiment, angle330is about 45 degrees. However, in alternate embodiments, a variety of angles may be achieved by various combinations of sector antennas and magnetic conductor materials. For example, the angle330may be from 35 degrees to 60 degrees in certain embodiments. In the case of a dual-band AMC strip, the radiation patterns, and the extent to which they are affected by the AMC material, may also be different for each band.

FIG. 5illustrates one embodiment of the present invention in which the sector antenna configuration is mounted flush to a metal housing510. That is, AMC520is coupled flush to housing510, and sector antenna550is coupled flush to AMC520. AMC520limits or suppresses surface currents for signals in the appropriate frequency band(s). In other words, AMC520improves isolation between antenna550and metal housing510, limiting or eliminating any effects of metal housing510on the shape and direction of radiation pattern560.

The inventive sector antenna configuration can be used in a variety of embodiments. For example,FIGS. 6–8illustrate embodiments that use multiple antennas to provide sectorized antenna coverage. Since sector antennas tend to perform better compared to omni-directional antennas, at least in one direction, using an array of multiple sector antennas to provide omni-directional coverage can provide superior connectivity.

FIG. 6illustrates one embodiment of a notebook computer600that has four mounting locations610on opposite edges630of its lid620. Thanks to the magnetic conductor material, a sector antenna configuration can be flushly mounted at each mounting location610, even if notebook600has a metal housing. By orienting the radiation patterns of a pair of sector antennas on each edge630in opposite directions, the pair of sector antennas can provide signal coverage for 180 degrees or more of azimuth. A pair of similarly oriented sector antennas on the opposite edge630can provide another 180 degrees of coverage. All together, the four sector antennas can provide 360 degrees of azimuth around the notebook.

The sector antennas can be oriented in any number of ways. For instance, an antenna mounted at a top mounting location on one edge of the notebook may be aligned so that the long axis of the antenna is parallel, or substantially parallel, to the long dimension of the edge of the notebook, with the radiation pattern angled up. The lower antenna on the same edge may also be mounted in a parallel configuration, but with the radiation pattern angled down. The antennas on the opposite side may use the same orientation. In another embodiment, the antennas may be aligned in a perpendicular, or substantially perpendicular, orientation to the long dimension of the edge of the notebook. In which case, the radiation patterns for the top sector antennas may angle toward the front, or screen, side of the lid, and the lower radiation patterns may angle to the rear side of the lid. Alternate embodiments may use any number of combinations of parallel and perpendicular orientations, with radiation patterns pointing up, down, frontward, or backward. While many sector antenna arrays can provide 360 degrees of azimuth, some embodiments may provide less than 360 degrees of azimuth. And, while edge mounting locations are often convenient to provide 360 degrees of coverage, the sector antenna configurations of the present invention can be used in any number of mounting locations.

For example,FIG. 9illustrates one embodiment of a dual-bands sector antenna configuration900. Much like antenna configuration300shown inFIGS. 3 and 4, sector antenna320can be mounted flush against dual-band AMC material910. Dual-band AMC strip910can approximate a perfect magnetic conductor for signals in two frequency bands, and differently alter the radiation pattern that sector antenna320. Would otherwise have in each band. In the illustrated embodiment, radiation pattern950may correspond to one frequency band that is flared up at an angle930, and radiation pattern952may correspond to another frequency band that is flared up at an angle932.

FIG. 7shows lid620from a top view with an array of four, perpendicularly mounted sector antennas750. In this top view, only one antenna750can be seen on each edge630, but there are actually two antennas750on each edge630. The four antennas750provide four radiation patterns710,720,730, and740. In other words, two out of the four antennas750are oriented to radiate down in the figure (patterns720and740), and two are oriented to radiate up in the figure (patterns710and730). Together, the patterns provide 360 degrees of azimuth around lid620.

FIG. 8illustrates another sector antenna array on a tablet computer810. Tablet810has a pair of sector antennas830mounted flush along each opposite edge820. Each pair of sector antennas is mounted with opposite orientations to provide 180 degrees of coverage.

Thus, a low profile, sector antenna is described. Whereas many alterations and modifications of the present invention will be comprehended by a person skilled in the art after having read the foregoing description, it is to be understood that the particular embodiments shown and described by way of illustration are in no way intended to be considered limiting. Therefore, references to details of particular embodiments are not intended to limit the scope of the claims.