Patent Application
20080079635
Antenna element 104 is disposed in antenna space 103. Since antenna 104 is adjacent to, rather than above, ground plane 101 and also does not have a conductive connection to ground plane 101, it is an ungrounded antenna element. Specifically, antenna element 104 is shown in this example as a monopole antenna element.
Projection 105 is an extension of ground plane 101 that is disposed in antenna space 103. Ground plane extension 105 can be part of the same conductive layer that forms ground plane 101 or can be independently formed or disposed on substrate 102. The dimensions of ground plane extension 105 and ground plane 101 together form a resonant length that can be used to transmit data signals. Specifically, when ground plane 101 and ground plane extension 105 are placed within the near field of antenna element 104, antenna element 104 can be operated as a capacitive feed that causes resonance along the resonant length described above. [This is true, right?] In other words, ground plane extension 105 is designed to adapt a length of a portion of ground plane 101 to conform to a resonant length that corresponds to an established communication band. In this way, the resonance of ground plane 101 can be optimized to provide additional performance to antenna system 100.
Substrate 102 is not limited to a single piece of substrate in various embodiments. In fact, substrate 102 can be made of two or more substrate portions, for example, with ground plane 101 disposed on one portion and antenna area 103 disposed on another portion and ground plane extension 105 connected to ground plane 101 through, for example, a soldered connection.
In this example, the proximity of the tip of the horizontal portion of antenna element 104 to extension 105 determines, at least in part, the amount of electromagnetic coupling that occurs between element 104 and the resonant structure formed by ground plane 101 and extension 105. Generally, the greater the distance, the less the coupling, and as coupling between a ground and an antenna increases, the bandwidth of antenna 104 is narrowed. Thus, while it is desirable to minimize coupling to some extent, some amount of coupling is desirable for the capacitive feeding to occur. Similarly, the horizontal orientation of this portion of antenna element 104 reduces coupling since it is substantially orthogonal to the resonant length corresponding the f3 band.
As shown, the length along the outside of the structure formed by ground plane 101 and extension 105 provides a third resonant length that corresponds to a frequency band f3 that is lower than either f1 or f2. In this example, the width at the top of extension 105 affects the resonant length such that a wider top portion lowers frequency band f3. The width at the bottom of extension 105, like the length of the horizontal portion of element 104, affects coupling between antenna element 104 and extension 105.
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In step 1002, a second element electromagnetically coupled to the ungrounded antenna element is resonated, thereby transmitting data in an established communication band, wherein a resonant length of the second element includes at least portions of a ground plane and a projecting member of the ground plane. In other words, coupling with the ungrounded antenna element causes the structure formed by a ground plane and its extension to resonate at its native frequency, thereby transmitting the data. In this example, the data signal of step 1001 includes data at a frequency that corresponds to the native frequency of the structure formed by the ground plane and its extension.
In this way, the ground plane of the antenna system is optimized to resonate at a frequency that corresponds to an established communication band, thereby adding at least one frequency band to the antenna system. This can be utilized to create a system that provides performance over a plurality of bands. A particular example is the UWB spectrum that includes bands from 3.1 GHz to 10.6 GHz in the United States (and other bands in various countries). UWB performance can be facilitated, at least in part, by some embodiments of the invention which provide broadband communications from both an ungrounded antenna element and from the ground plane so that operation over a wider spectrum is achieved.
Other applications of various embodiments include providing antenna systems for wireless networking, e.g., for IEEE 802.11, or for advanced cellular handsets that use, e.g., various Global Systems for Mobile Communications (GSM) bands. In fact, because of the increased spectrum provided by optimizing the ground plane resonance with a ground plane extension, various embodiments can find use in a variety of high data rate communications applications now known or later developed.
Additional advantages of some embodiments include relatively cost-efficient production, especially in PCB designs, since the ground plane extension can be created with few extra steps (if any). In some embodiments, manufacturing a ground plane extension requires only etching a ground plane shape that includes a projection. Some embodiments are manufactured using other steps such as, for example, mounting a lumped element or soldering a connection between the ground plane and its extension.
Other advantages of some embodiments include increasing the number and/or size of radiating structures in an antenna system while incurring minimal increases in design volume. For instance, in some designs that include both a ground plane and a reserved antenna space, the extension can be disposed on the antenna space, thereby requiring a negligible difference in volume over that of a similar design without an ground plane extension.
A further advantage of some embodiments is apparent when compared to prior art antenna systems that use ground plane extensions as parasitic elements. In those prior art embodiments, a parasitic element extends from a ground plane and provides an extra resonance to the antenna system. The resonant length is due to the length of the parasitic only, such that the added resonance is the parasitic element's own resonance and tends to be quite narrow. However, various embodiments of the invention use a ground plane extension to create a resonant length that includes at least a portion of the length of the extension and a portion of the length of the ground plane, thereby using the ground plane plus its extension as a radiating structure. Typically, the result is that the added band is lower in frequency and much wider than a band added by a parasitic extension.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
