A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
1. Field of Invention
The invention relates generally to antennas for radiating and/or receiving electromagnetic energy, and specifically in one aspect to an antenna in which the radiators are conductor coatings of a dielectric chip; the chip may be, e.g., mounted on a circuit board of a radio device, wherein the circuit board is a part of the antenna structure.
2. Description of Related Technology
In small-sized radio devices, such as mobile phones, the antenna or antennas are preferably placed inside the cover of the device, and naturally the intention is to make them as small as possible. An internal antenna has usually a planar structure so that it includes a radiating plane and a ground plane below it. There is also a variation of the monopole antenna, in which the ground plane is not below the radiating plane but farther on the side. In both cases, the size of the antenna can be reduced by manufacturing the radiating plane on the surface of a dielectric chip instead of making it air-insulated. The higher the dielectricity of the material, the smaller the physical size of an antenna element of a certain electric size. The antenna component becomes a chip to be mounted on a circuit board. However, such a reduction of the size of the antenna entails the increase of losses and thus a deterioration of efficiency.
A drawback of the above described antenna structure is that in spite of the ostensible optimization of the feed circuit, waveforms that increase the losses and are effectively useless with regard to the radiation produced by the device are created in the dielectric substrate. The efficiency of the antenna is thus comparatively poor and not satisfactory. In addition, there is significant room for improvement if a relatively even radiation pattern, or omnidirectional radiation, is required.
The present invention addresses the foregoing needs by disclosing antenna component apparatus and methods.
In a first aspect of the invention, an antenna is disclosed. In one embodiment, the antenna comprises: a dielectric substrate having a first dimension and a second dimension, the dielectric substrate being disposed on a mounting substrate and at least partially coupled to a ground plane; a conductive layer having a first portion and a second portion to form a first resonant element and a second resonant element respectively; an electromagnetic coupling element disposed between the first portion and the second portion; and a feed structure connected to the first portion and coupled through the electromagnetic coupling element to the second portion so as to form a resonant structure between the first resonant element, the second resonant element, the mounting substrate, and the ground plane.
In another embodiment, the antenna is manufactured according to the method comprising: mounting a dielectric element at least partially on a ground plane disposed on a substrate; disposing a conductive first portion at least partially on an upper surface and a first side surface of the dielectric element, and a conductive second portion at least partially on an upper surface and a second side surface of the dielectric element; disposing a feed structure asymmetrically coupled to at least one edge or side of the first portion or the second portion; and forming a mutual coupling region between the first portion and the second portion to adjust an antenna resonant frequency.
In still another embodiment, the antenna comprises a dielectric substrate having an upper surface and a lower surface; and at least two radiating elements mounted at least partially on the upper surface and one of the at least two radiating elements partially coupled along exterior edges to a ground plane partially connected to the lower surface. The at least two radiating elements are separated by a slot, the slot adapted to increase an effective electrical length of the at least two radiating elements; and a resonant structure configured so that the operation of the antenna is responsive to at least one of the following: i.) a dimension of the slot; ii.) a dimension of each of the at least two radiating elements, iii.) a separation length of the ground plane from an exterior surface of the antenna, and iv.) a feed connection point connecting to one of the at least two radiating elements.
In yet another embodiment, the antenna comprises a high-efficiency antenna resulting from use of an antenna component that is comparatively simple in structure, and which allows for an uncomplicated current distribution within the antenna elements, and correspondingly a simple field image in the substrate without superfluous or ancillary waveforms.
In a second aspect of the invention, a radio frequency device is disclosed. In one embodiment, the device comprises: an antenna deposited on a dielectric substrate; a conductive coating deposited on the dielectric substrate, the conductive coating having a first portion comprising a first resonator and a second portion comprising a second resonator. The first resonator and the second resonator are separated at respective open ends by a distance d so as to at least in part determine an operating frequency. The device further comprises a feed structure coupled to the conductive coating; and a resonant structure formed by the first resonator, the second resonator, the substrate, and a ground plane deposited on the substrate, the structure configured to operate substantially within a selected frequency band.
In another embodiment, the device comprises a substrate; a conductive surface adapted to form a ground plane; an antenna comprising a dielectric element having a longitudinal direction and a transverse direction, the element being deposited at least partially on the ground plane; a conductive coating deposited on the dielectric element, the conductive coating having a first portion forming a first resonator and a second portion forming a second resonator; and a feed structure coupled to the conductive coating. Open ends of the first resonator and the second resonator are separated by a non-conductive slot to at least electromagnetically couple the first resonator and the second resonator, and to form a resonant structure with the substrate and the ground plane.
In a third aspect of the invention, a method for tuning an antenna is disclosed. In one embodiment, the antenna is disposed on a substrate, and the method comprises: setting an electrical length of a first conductive element between the first portion of a first radiating element and a ground plane; setting an electrical length of a second conductive element between the second portion of a second radiating element to the ground plane to achieve frequency tuning of the antenna; setting at least one of a feed structure length or connection point to the first portion of the radiating element; setting a width or length of a slot element to at least adjust the coupling of energy between the first radiating element and the second radiating element; and setting a spacing of the first radiating element and the second radiating element extended from the ground plane to determine at least in part an omni-directional radiation pattern.
In another embodiment, both the tuning and the matching of the antenna is carried out without discrete components; i.e., by shaping the conductor pattern of the circuit board near the antenna component.
In a fourth aspect of the invention, a chip antenna is disclosed. In one embodiment, the chip antenna comprises: a dielectric substrate with an upper and lower surface, a first and a second head and a first and a second side, and on surface of the substrate a first and a second radiating element; a slot disposed substantially between the elements; the first radiating element connected to a feed conductor of the antenna at a first point and to a ground plane of the radio device at a second point, and the second radiating element connected at a third point to a ground conductor and through it galvanically to the ground plane.
In one variant, and in order to reduce the antenna losses and to provide substantially omnidirectional radiation, the first radiating element comprises a portion covering the first head and another portion covering the upper surface, and the second radiating element comprises a portion covering the second head and another portion covering the upper surface so that the slot extends from the first side to the second side and divides the upper surface to two parts of the substantially same size, over which slot the second radiating element is arranged to obtain a feed electromagnetically.
In a fifth aspect of the invention, a chip component for implementing an antenna of a radio device is disclosed. In one embodiment, the component comprises: a dielectric substrate comprising an upper surface, a lower surface, a first head, a second head, a first side, and a second side; a first antenna element coupled to a feed conductor at a first point and to a ground plane of the radio device at a second point, the first antenna element at least partially disposed on the first head and at least partially on the upper surface; a second antenna element coupled to the ground plane at a third point, the second antenna element at least partially disposed on the second head and at least partially on the upper surface; and a slot extended between at least a portion of the first antenna element and the second antenna element to provide electromagnetic energy to feed the second antenna element.
In another embodiment, the chip component is produced by the method comprising using of a semiconductor technique; i.e., by growing a metal layer on the surface of the substrate (e.g. quartz substrate), and removing a part of it so that the elements remain.
In the following, the invention will be described in more detail. Reference will be made to the accompanying drawings, wherein:
a and 4b present another example of the chip component of an antenna according to the invention;
a-d show examples of shaping of the slot between the radiating elements in an antenna according to the invention;
Reference is now made to the drawings wherein like numerals refer to like parts throughout.
As used herein, the terms “wireless”, “radio” and “radio frequency” refer without limitation to any wireless signal, data, communication, or other interface or radiating component including without limitation Wi-Fi, Bluetooth, 3G (3GPP/3GPPS), HSDPA/HSUPA, TDMA, CDMA (e.g., IS-95A, WCDMA, etc.), FHSS, DSSS, GSM, UMTS, PAN/802.15, WiMAX (802.16), 802.20, narrowband/FDMA, OFDM, PCS/DCS, analog cellular, CDPD, satellite systems, millimeter wave, or microwave systems.
Additionally, as used herein, the term “chip antenna” means without limitation an antenna structure comprising a chip component. In addition to the actual chip component itself, the structure may comprise the ground arrangement surrounding it and the antenna feed arrangement.
It will further be appreciated that as used herein, the qualifiers “upper” and “lower” refer to the relative position of the antenna shown in
Overview In one salient aspect, the present invention comprises a chip component (and antenna formed therefrom) which overcomes the aforementioned deficiencies of the prior art.
Specifically, one embodiment of the invention comprises a plurality (e.g., two) radiating antenna elements on the surface of a dielectric substrate chip. Each of them is substantially symmetric and of a similar or same size, and covers one of the opposing heads, and part of the upper surface of the (e.g., rectangular) chip. In the middle of the upper surface between the elements is formed a slot. The circuit board or other substrate, on which the chip component is mounted, has no ground plane under the chip nor on its sides up to a certain distance. The lower edge of one of the radiating elements is galvanically connected to the antenna feed conductor on the circuit board, and at another point to the ground plane, while the lower edge of the opposite radiating element, or the parasitic element, is galvanically connected only to the ground plane. The parasitic element obtains its feed through said electromagnetic coupling, and both elements resonate with substantially equal strength at the operating frequency.
In one embodiment, the aforementioned component is manufactured by a semiconductor technique; e.g., by growing a metal layer on the surface of quartz or other type of substrate, and removing a part of it so that the elements remain.
In addition, the invention has the advantage that the efficiency of an antenna made using such a component is high, in spite of the use of the dielectric substrate. This is due to the comparatively. simple structure of the antenna, which produces an uncomplicated current distribution in the antenna elements, and correspondingly a simple field image in the substrate without “superfluous” waveforms.
Moreover, the invention has an excellent omnidirectional radiation profile, which is largely due to the symmetrical structure, shaping of the ground plane, and the nature of the coupling between the elements.
A still further advantage of the invention is that both the tuning and the matching of an antenna can be carried out without discrete components; i.e., just by changing the width of the slot, shaping the conductor pattern of the circuit board near the antenna component, etc.
Yet another advantage of the invention is that the antenna according to it is very small and simple and tolerates relatively high field strengths.
Detailed discussions of various exemplary embodiments of the invention are now provided. It will be recognized that while described in terms of particular applications (e.g., mobile devices including for example cellular telephones), materials, components, and operating parameters (e.g., frequency bands), the various aspects of the invention may be practiced with respect to literally any wireless or radio frequency application.
Moreover, the parasitic element obtains its feed through the coupling prevailing over the slot and not through the coupling between the ground conductor of the parasitic element and the feed conductor. The first radiating element 220 of the antenna 200 comprises a portion 221 partly covering the upper surface of an elongated, rectangular substrate 210 and a head portion 222 covering one head of the substrate. The second radiating element comprises a portion 231 symmetrically covering the upper surface of the substrate partly and a head portion 232 covering the opposite head. Each head portion 222 and 232 continues slightly on the side of the lower surface of the substrate, thus forming the contact surface of the element for its connection. In the middle of the upper surface between the elements there remains a slot 260, over which the elements have an electromagnetic coupling with each other. The slot 260 extends in this example in the transverse direction of the substrate perpendicularly from one lateral surface of the substrate to the other, although this is by no means a requirement for practicing the invention.
The chip component 201, or the substrate with its radiators, is in
The tuning of the antenna is also influenced by the shaping of the other parts of the ground plane, too, and the width d of the slot 260 between the radiating elements. There is no ground plane under the chip component 201, and on the side of the chip component the ground plane is at a certain distance s from it. The longer the distance, the lower the natural frequency. In turn, increasing the width d of the slot increases the natural frequency of the antenna. The distance s also has an effect on its impedance. Therefore the antenna can advantageously be matched by finding the optimum distance of the ground plane from the long side of the chip component. In addition, removing the ground plane from the side of the chip component improves the radiation characteristics of the antenna, such as its omnidirectional radiation.
At the operating frequency, both radiating elements together with the substrate, each other and the ground plane form a quarter-wave resonator. Due to the above described structure, the open ends of the resonators are facing each other, separated by the slot 260, and said electromagnetic coupling is clearly capacitive. The width d of the slot can be dimensioned so that the resonances of both radiators are strong and that the dielectric losses of the substrate are minimized. The optimum width is, for example, 1.2 mm and a suitable range of variation 0.8-2.0 mm, for example. When a ceramic substrate is used, the structure provides a very small size. The dimensions of a chip component of an exemplary Bluetooth antenna operating on the frequency range 2.4 GHz are 2×2×7 mm3, for example, and those of a chip component of a GPS (Global Positioning System) antenna operating at the frequency of 1575 MHz 2×3×10 mm3, for example.
a shows another example of the chip component of an antenna according to the invention. The component 401 is mainly similar to the component 201 presented in
In
a-d show examples of shaping of the slot between the radiating elements in an antenna according to the invention. In
In
The curve 91 shows the fluctuation of the reflection coefficient S11 as a function of frequency in the antenna, the size of the chip component of which is 10×3×4 mm3, and the slot between the radiating elements is perpendicular. The resonance frequency of the antenna, which is approximately the same as the medium frequency of the operation band, falls on the point 1725 MHz.
The curve 92 shows the fluctuation of the reflection coefficient, when the slot between the radiating elements is diagonal according to
The curve 93 shows the fluctuation of the reflection coefficient, when the slot between the radiating elements has turns according to
A ceramics having the value 20 of the relative dielectric coefficient Fr is used for the antenna in the three cases of
While the above detailed description has shown, described, and pointed out novel features of the invention as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art without departing from the invention. The foregoing description is of the best mode presently contemplated of carrying out the invention. This description is in no way meant to be limiting, but rather should be taken as illustrative of the general principles of the invention. The scope of the invention should be determined with reference to the claims.
Number | Date | Country | Kind |
---|---|---|---|
20040892 | Jun 2004 | FI | national |
This is a continuation application of and claims priority to International PCT Application No. PCT/FI2005/050089 having an international filing date of Mar. 16, 2005, which claims priority to Finland Patent Application No. 20040892 filed Jun. 28, 2004, each of the foregoing incorporated herein by reference in its entirety. This application is related to co-owned and co-pending U.S. patent application Ser. No. 11/544,173 filed Oct. 5, 2006 and entitled “Multi-Band Antenna With a Common Resonant Feed Structure and Methods”, and co-owned and co-pending U.S. patent application Ser. No. 11/603,511 filed Nov. 22, 2006 and entitled “Multiband Antenna Apparatus and Methods”, each also incorporated herein by reference in its entirety. This application is also related to co-owned and co-pending U.S. patent application Ser. No. 11/648,429 filed contemporaneously herewith and entitled “Antenna, Component And Methods”, also incorporated herein by reference in its entirety.
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Number | Date | Country | |
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Parent | PCT/FI2005/050089 | Mar 2005 | US |
Child | 11648431 | US |