Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2002-03-01
2004-10-19
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
Reexamination Certificate
active
06806831
ABSTRACT:
TECHNICAL FIELD
The invention concerns antennas, specifically small stacked patch antennas.
BACKGROUND
The size of mobile wireless terminals is decreasing as digital and analog components become increasingly integrated and miniaturized. Apart from user interface aspects, the main limiting factor on further size reductions are the antennas. The antennas are now a dominating factor in the visual appearance of many mobile devices. From an esthetic point of view it would be desirable to have antennas that are small. Further, manufacturing costs can usually be reduced with smaller antennas.
Wireless local-area network (LAN) solutions for office use are rapidly becoming a prominent competitor to traditional wireline networks. A major advantage of wireless LANs is the mobility they offer. A computer can be connected to a wireless LAN from anywhere within the LAN's coverage area. The antennas for the mobile terminals of the wireless LANs are normally intended for installation on a PC-card, which puts constraints on the allowable antenna size. However, the dimensions of antennas are wavelength dependent. Additionally an antenna's bandwidth and radiation efficiency are limited by the effective volume, in terms of wavelengths, that the antenna occupies.
Another constraint put on antennas is their radiation pattern. Wireless LAN antennas mounted on, for example, a PC-card should be small and radiate primarily in the horizontal plane. Indoor wave propagation tends to be confined to incidence angles within a narrow angular interval centered around the horizon. The antenna should also have an omni-directional radiation pattern, i.e. the radiation pattern should be substantially independent of the azimuthal angle, in order to be able to register the various wave components of a typical multipath propagation channel common in indoor environments. Thus, a wireless LAN antenna should be wideband, efficient and substantially omni-directional. Further, such an antenna should make an optimum use of its volume in order to fit into an alloted space in a respective device. Wireless LAN antennas intended to be mounted on a PC-card (direction of mounting in relation to computer orientation when in use should be taken into account), should therefore be planar and low-profile with a negligible thickness.
Additionally a wireless LAN antenna for indoor use should, apart from an omnidirectional radiation pattern with an essentailly constant radiation pattern in the azimuthal (horizontal) direction, preferably also have a null-depth, or a near null-depth, in the broadside (vertical) direction. A null-depth, or near null-depth in the broadside direction is important to enable different wireless LANs on different floors to co-exist with as little cross interference as possible.
A variety of small low profile antennas have been proposed. Examples include everything from antennas based on modifications of the traditional monopole antenna to elaborate optimized antenna schemes involving multi-layered structures with meandering lines, ceramic materials, and various types of impedence matching schemes. Most types of low profile antennas with wide bandwidths have semi-isotropic radiation patterns with maximum radiation, or at least significant radiation levels, in the broadside, i.e. vertical, direction. One type of antenna that addresses some of the above mentioned constraints is the bent stacked slot antenna (BSSA). The BSSA antenna achieves a relatively wide bandwidth and small size and makes use of a center strip of a middle patch as an integrated impedance matching unit. An example of such an antenna is described in the European patent application EP 795926. However, a disadvantage with the BSSA type of antenna can in some applications be considered to be the inherent azimuthal gain variations and relatively narrow bandwidth, i.e. there is a need for a more omni-directional antenna with a wider bandwidth.
SUMMARY
An object of the invention is to define a low-profile antenna which provides a high efficiency, good omni-directionality and a wide bandwidth.
Another object of the invention is to define a low-cost low profile antenna which is suitable to be mounted on a PC-card.
A further object of the invention is to define a low profile antenna which when mounted horizontally provides a substantially omni-directional radiation pattern in the azimuthal direction and at least a near null-depth in the broadside direction.
The aforementioned objects are achieved according to the invention by a stacked patch antenna. The stacked patch antenna is intended to be mounted on a ground plane. The antenna comprises two stacked metallic patches. The patches are stacked on top of each other. The patch to be mounted closest to the ground plane, the middle patch, comprises at least two conductors at or close to its edge which conductors are intended to be connected to the ground plane to thereby ground the patch in two zero potential areas. The patch to be mounted furthest away from the ground plane, the top patch, comprises at least two conductors at: or close to its edge which electrically interconnect the two patches. The conductors electrically interconnecting the patches should preferably be connected to the middle patch at least proximate the respective zero potential areas of the middle patch. The conductors preferably also provide structural strength to the antenna and provide mounting means and support for the patches. The middle patch is fed at a feed area which is at least proximate the geometric center of the middle patch. The middle patch further comprises at least two apertures completely within the circumference of the middle patch. The apertures do not divide the middle patch into two or more physically and/or electrically separated parts, i.e. the middle patch is in one piece. Preferably the apertures are placed in such a way that at least two paths are provided from each place which is grounded on the middle patch to the feed area, i.e. each aperture blocks a direct line from the feed area to a respective place which is grounded. There is always at least one physical/electrical connection between the feed area and each zero potential area of the middle patch. Thereby enabling radiation from a slot defined by the edge of the top patch and the edge of the middle patch and a slot defined by the edge of the middle patch and the ground plane.
The aforementioned objects are also achieved according to the invention by a stacked patch antenna comprising two metallic patches stacked on top of each other. The middle patch comprises at least two conductors at or close to its edge, which conductors are intended to be connected to a ground plane to thereby ground the patch in two places. The top patch comprises at least two conductors at or close to its edge which electrically interconnect the two patches. The middle patch is fed at a feed area which is at least proximate Its geometric center. The middle patch further comprises at least two apertures completely within its circumference, i.e. each aperture having a respective unbroken circumference. Thereby enabling radiation from slots defined by the edge of the top patch and the edge of the middle patch and defined by the edge of the middle patch and the ground plane.
The aforementioned objects are also achieved according to the invention by a low profile antenna structure. The antenna structure comprises a first metallic patch and a second metallic patch stacked over a ground plane. The first patch comprises a circumference along a patch edge of the first patch. The second patch comprises a circumference along a patch edge of the second patch. The first patch is arranged between the ground plane and the second patch. The first patch is grounded at at least a first zero potential area by electrical connection with the ground plane and a second zero potential area by electrical connection with the ground plane. The first patch is further fed at a single feed area. The second patch is electrically interconnected to the first patch. According to the invention the firs
Grincwajg Anna
Johansson Martin
Lindgren Stefan
Phan Tho
Telefonaktiebolaget LM Ericsson (publ)
LandOfFree
Stacked patch antenna does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stacked patch antenna, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stacked patch antenna will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3321963