Patent Application
20100289701
Contemporary consumers want small, reasonably portable electronic devices. At the same time, such devices are becoming more and more multifunctional, providing many features. As a result, numerous component parts need to be put into the device and integrated together. Thus, as the size of such devices shrink, the components need to be smaller.
By way of example, contemporary gaming consoles not only provide gaming functionality, but also provide networking experiences, such as internet competition, movie streaming and so forth. At the same time, such gaming consoles include wireless communication links for controller-to-console communications, and internet communications (although a wired connection may be used).
An antenna is thus needed to provide reliable communication links (e.g., via Bluetooth®, Wi-Fi and/or proprietary wireless links) between such a console or other devices and the peripheral devices with which it communicates. In general, a patch antenna is used in such devices, in which the physical position of the patch antenna is fixed in the device.
As the device form factor gets smaller, the size of the patch antenna also needs to be smaller to meet the physical design specifications. However, when attempting to shrink the size of the antenna, the bandwidth needed to meet the specified frequency range becomes too small using existing antenna designs. Desired results can likely be obtained by using relatively expensive dielectric materials for the antenna substrate; however the expense of such materials is unacceptable for products that are to be mass produced.
In sum, existing antenna technology is unable to deliver the desired bandwidth and cost targets for physically small and fixed patches as specified by small product form factors. Any technology that can achieve the desired bandwidth with acceptable cost is thus valuable.
This Summary is provided to introduce a selection of representative concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used in any way that would limit the scope of the claimed subject matter.
Briefly, various aspects of the subject matter described herein are directed towards a technology by which a patch antenna meets specified frequency and bandwidth requirements via slits on a patch element of the antenna. For example, for a dual-polarized antenna having two feedlines, the patch has three slits that are configured to determine the antenna's frequency characteristics, and no (or a substantially reduced) fourth slit, which by its elimination (or reduction) provides wider bandwidth.
The slits may be physically configured to provide the desired frequency characteristics, e.g., via their size (width and/or height dimensions). Alternatively, the slits may be electronically configured and/or mechanically configured.
In one implementation, the patch is coupled to feedlines, such as via aperture coupling through slots in a ground plane; the ground plane is on the opposite side of a substrate that supports the feedlines, e.g., on its underside. For diagonal feedlines, with respect to the x and y directions, one of the three frequency slits extends substantially horizontally, and the other two extend substantially vertically, that is, one extends upward and one extends downward from an respective lower and upper edge of the patch.
Other advantages may become apparent from the following detailed description when taken in conjunction with the drawings.
The present invention is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements and in which:
Various aspects of the technology described herein are generally directed towards a patch antenna with slits that are configured to provide desired frequency and/or bandwidth characteristics. In one implementation, for a dual-polarized design, three slits (“frequency slits”) in the patch provide the desired frequency, while the conventional fourth slit (a “bandwidth slit”) is reduced in size (including eliminating the fourth slit altogether by having it reduced to zero size) for impedance bandwidth enhancement on small size substrates. Note that heretofore, four slits in the patch have been used, however as described herein, eliminating (or reducing the size of) one of the slits increases the impedance bandwidth of the antenna.
While a gaming console is exemplified herein as one device that benefits from such an antenna/antenna system, it should be understood that this is only one practical example usage. Other uses for such an antenna are straightforward to implement, such as in personal computers, wireless access points/routers, printers, remote controlled appliances, and virtually any type of device that uses or may benefit from wireless communications. Further, the type of wireless communication can be at any suitable frequency using any wireless technology (e.g., Bluetooth®, Wi-Fi or proprietary technologies).
As such, the present invention is not limited to any particular embodiments, aspects, concepts, structures, functionalities or examples described herein. Rather, any of the embodiments, aspects, concepts, structures, functionalities or examples described herein are non-limiting, and the present invention may be used various ways that provide benefits and advantages in antenna technology and wireless communication technology in general.
Returning to
Note that the dashed boxes associated with elements 114 and 220 are provided to show an approximate positioning and size relationship with the other antenna elements in one implementation. However, the illustrated relative sizes are only example approximations for one implementation, and are not necessarily to scale.
As is known in dual-polarized designs, one of the feedlines is selected depending on current conditions (generally corresponding to the current orientation of the peripheral device's antenna). With respect to the slots, feedlines and feed points, because the ground plane 112 will likely be loaded with other RF/digital components, the feedlines 106 and 107 are positioned underneath. Aperture coupling via the slots 110 and 111 is employed such that energy from an actively selected feedline (e.g., 106) couples at the respective feed point (e.g., 108) through the respective aperture (one of the slots, e.g., 110) in the ground plane 112 to the patch 114 for excitation. Maintaining symmetry for dual-polarized designs allows the antenna performance to be nearly the same for either feed.
The radiating patch 114 is layered on a top substrate 220 as shown in
In one implementation, the slit 115 is on the left side of the patch 114, symmetric with respect to a horizontal line that crosses the midpoint of the patch 114. The slit 116 extends vertically from the bottom of the patch 114 to a position close to the center of the patch 114. The slit 117 extends vertically from the top of the patch 114 to a position close to the center of the patch 114.
Note that
The insulator 222, when formed from a lossless dielectric such as air, can significantly increase the antenna gain when inexpensive and relatively high loss substrates such as FR-4 are used for part of the antenna implementation. If air is the desired insulator 222, the antenna's substrate may be modified in various ways to include locations where plastic spacers or the like may be used to attach the upper substrate 220 to the ground plane 112, e.g., as exemplified in
Further note that the dielectric layer insulator may be eliminated by selecting appropriate dielectrics for the remaining layers of the antenna structure. The dimensions of the patch/slits are adjustable to account for the dielectric layer structure of the antenna stack; regardless, the three slit design that enhances bandwidth in a dual feedline antenna applies.
An alternative implementation of the antenna may use a multilayer circuit board structure. For example, the layers shown in
In one implementation, the substrate material for the substrates 220 and 104 is FR-4, which has a dielectric constant (Er) of 4.45±0.25 and a loss tangent (tan δ) of 0.025. The thickness for the substrate 104 between the ground plane 112 and the feedlines 106 and 107 is h1=39 mils, while the thickness of the substrate 220 between the insulator 222 and the patch 114 is h2=62 mils. The thickness of the insulator 222 (for an air layer) is hair=39 mils. The thickness for the copper (Cu) traces is 1.4 mils, which includes the feedlines 106 and 107, the patch 114 and the ground plane 112. In this implementation, the feedlines 106 and 107 are 71 mils wide in order to provide a 50 ohm input without any discontinuities.
In a gaming console implementation, such an outward facing antenna 330 may provide the communication link between the console and the user's peripheral device (e.g., a controller, joystick, and so forth). One such antenna design operates between 2.4-2.483 GHz, which is the ISM band for Bluetooth® and Wi-Fi connectivity. Notwithstanding, the technology described herein is broadly applicable to patch antennas at any operating frequency range.
The configuration of this antenna makes it straightforward to integrate the antenna 102 to a printed circuit board without the need to modify other circuitry on the board. Note however that the patch 114 and the substrate need not be directly attached to the printed circuit board. In a transmitting (or receiving) mode, the feedlines 106 and 107 allow for two polarizations to be excited individually based on the alignment of the receiving (or transmitting) antenna. The feeding points of the feedlines may be relatively close, e.g., in order to connect the terminals of a switch, a PIN diode or other feed network. The switch, the PIN diode or other feed circuitry serves as the switching mechanism to determine which polarization is excited. Additionally, feedlines 106 and 107 can be excited simultaneously to provide increased signal throughput by way of a larger range of polarizations.
To summarize the operating characteristics of the rectangular patch, having three slits with dual-polarization provides resonant frequency reduction for a given patch size, while bandwidth is increased by reducing or eliminating the fourth slit. The resonant frequency of the antenna is reduced by elongating the surface current paths that define the resonant frequency of operation, as generally shown by the arrows in
More particularly, the position of the slits provides optimal impedance matching. The length of the slits determines the resonant frequency, that is, when the slits are longer, the resonant frequency decreases. However, the decrease in resonant frequency comes at the expense of reduced impedance bandwidth.
As described herein, eliminating (or substantially reducing the size of) the conventionally-used fourth slit widens the impedance bandwidth that is lost.
In the return loss, it is seen that the impedance bandwidth is much wider in the design with three slits (the line 770) as opposed to the design with four (the line 772). This is likely due to the existence of a second mode that exists at a higher frequency. This higher mode frequency is close enough to the fundamental mode so the impedance bandwidth of both is combined, leading to a larger overall impedance bandwidth. In this particular implementation, the absolute impedance bandwidth of the three slit design is approximately 2.5 times larger than the design with four slits.
In
Turning to other variations and alternatives, it should be noted that if only linear polarization is needed, then only two slits are needed to provide the desired frequency and bandwidth results. For example, in
As another alternative,
As shown via the feedlines in
Turning to another aspect generally represented in
For example, an electronic device such as a variable resistor, a set of control diodes, and so forth may be controlled with control currents to alter the surface currents of a patch 1214, as if a slit (or slot) was present with effectively variable dimensions. A mechanical device may likewise be used as the variable control mechanism 1290, e.g., to change the physical properties of the surface and thus the surface currents. Such a variable control mechanism 1290 may be dynamic (e.g., processor-based) or static (e.g., manually tuned once). Further, as depicted by the shading within the slits in
While the invention is susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents failing within the spirit and scope of the invention.
