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 electro-magnetic energy, and specifically in one aspect to a component, where conductive coatings of a dielectric substrate function as radiators of an antenna. The invention also relates to an antenna made by using such a component.
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 optimization of the feed circuit, waveforms that increase the losses and are useless with regard to the radiation are created in the dielectric substrate. The efficiency of the antenna is thus not satisfactory. In addition, the antenna leaves 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 element having a longitudinal direction and a transverse direction, the element being deposited at least partially on a ground plane disposed on a substrate; 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. In one variant, 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 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 coating as a first portion and a second portion on the dielectric element; disposing a feed structure coupled to at least one of the first portion and the second portion; and forming a non-conductive slot coupled between the first portion and the second portion.
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 substantially on a dielectric substrate having a longitudinal direction and a transverse direction; a conductive coating deposited on the dielectric substrate, the conductive coating having a first portion that forms a first resonator and a second portion that forms a second resonator, the first resonator and the second resonator separated at open ends by a non-conductive slot to provide frequency tuning; 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 and configured to operate 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; and setting at least one dimension of the ground plane to adjust an omni-directional antenna radiation pattern. In one variant, the first portion and the second portion are separated by a non-conductive slot so as to form a resonant structure, the resonant structure having an operating frequency determined at least in part by a dimension of the non-conductive slot.
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, an antenna is disclosed comprising an antenna component. In one embodiment, the component comprises a dielectric substrate and a conductive layer that is at least partially coupled to a ground plane, the conductive layer partitioned at least in part by a non-conductive slot. In one variant, the non-conductive slot forms at least in part a first radiating element and a second radiating element, the first and the second radiating elements having an effective electrical length being related at least in part to a dimension of the non-conductive slot. A resonant structure is formed substantially based on the first radiating element, the second radiating element, the non-conductive slot, the ground plane proximate to the antenna component, and location of at least one feed point connection of at least one of the first radiating element and the second radiating elements, so to provide a substantially omni-directional radiation pattern during use.
In a fifth aspect of the invention, an antenna component for implementing an antenna of a radio device is disclosed. In one embodiment, the antenna component comprises: a dielectric element having an upper surface and a lower surface, a first and a second head, and a first and a second side; a first antenna element disposed substantially on a surface of the dielectric element and adapted to be 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, the first antenna element comprising the first head and a first portion of the upper surface; a second antenna element disposed substantially on a surface of the dielectric element and adapted to be connected to the ground plane at a third point, the second antenna element comprising the second head and a second portion of the upper surface; and a slot formed between the first portion and the second portion of the upper surface to couple electro-magnetic energy between the first antenna element and the second antenna element. In one variant, the first and second points are formed on the lower surface of the dielectric element proximate to an edge of the first head; and the third point is formed on the lower surface of the substrate proximal to an edge of the second head.
In a sixth aspect of the invention, an antenna component for implementing an antenna of a radio device is disclosed. In one embodiment, the component comprises: a first and a second antenna element; and a dielectric substrate with an upper and lower surface, a first and a second head, and a first and a second side. The first antenna element is located on at least one of the upper and lower surfaces of the substrate, and is arranged to be connected to feed conductor of the antenna at a first point, and to ground plane of the radio device at a second point, and the second antenna element is located on at least one of the upper and lower surfaces of the substrate, and is arranged to be connected to the ground plane at a third point.
In another embodiment, the antenna 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, in which:
a-d present examples of a shaping the slot between the antenna elements in the antenna component according to the invention;
a and 5b present an example of an antenna component 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, it will be appreciated that as used herein, the qualifiers “upper” and “lower” refer to the relative position of the antenna shown in
In one salient aspect, the present invention comprises an antenna 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 substantially covers one of the opposing heads, and part of the upper surface of the chip. In the middle of the upper surface between the elements is formed a narrow slot. The lower edge of one of the antenna elements is galvanically coupled to the antenna feed conductor on the circuit board, and at another point to the ground plane, while the lower edge of the opposite antenna element, or the parasitic element, is galvanically coupled only to the ground plane. The parasitic element obtains its feed through the electromagnetic coupling over the slot, and both elements resonate with substantially equally strength at the designated 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.
The antenna component disclosed herein has as one marked advantage a very small size. This is due primarily to the high dielectricity of the substrate used, and that the slot between the antenna elements is comparatively narrow. Also, the latter fact makes the “electric” size of the elements larger.
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 shaping the conductor pattern of the circuit board near the antenna component.
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 gets its feed through the coupling prevailing over the slot, and not through the coupling between the feed conductor and the ground conductor of the parasitic element. The first antenna element 220 of the antenna component 201 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 a part of the substrate upper surface 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 electro-magnetic coupling with each other. In the illustrated example, the slot 260 extends 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.
In
The tuning of the antenna of the illustrated embodiment 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 antenna elements. There is no ground plane under the antenna component 201, and on the side of the component the ground plane is at a certain distance s from it. The longer the distance, the lower the natural frequency. Also reducing the slot width d lowers the antenna natural frequency. The distance s has an effect on the impedance of the antenna also. Therefore, the antenna can advantageously be matched by finding the optimum distance of the ground plane from the long side of the component. In addition, removing the ground plane from the side of the component improves the radiation characteristics of the antenna, such as its omnidirectional radiation. When the antenna component is located on the inner area of the circuit board, the ground plane is removed from its both sides.
At the operating frequency, both antenna 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 the electromagnetic coupling is clearly capacitive. The width of the slot d can be dimensioned so that the dielectric losses of the substrate are minimized. One 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, this structure provides a very small size. The dimensions of a 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 component of a GPS (Global Positioning System) antenna operating at the frequency of 1575 MHz are 2×3×10 mm3, for example. On the other hand, the slot width can be made very small, further to reduce the component size. When the slot becomes narrower, the coupling between the elements strengthens, of course, which strengthening increases their electric length and thus lowers the natural frequency of the antenna. This means that a component functioning in a certain frequency range has then to be made smaller than in the case of a wider slot.
a-d show examples of a shaping the slot between the antenna elements in the antenna component according to one embodiment of the invention. The antenna component is seen from above in each of the four drawings. In
In
When a very narrow slot between the antenna elements is desired, a semiconductor technique can be applied. In that case, the substrate is optimally chosen to be some basic material (e.g., wafers) used in the manufacturing process of semiconductor components, such as quartz, gallium-arsenide or silicon. A metal layer is grown on the surface of the substrate e.g. by a sputtering technique, and the layer is removed at the place of the intended slot by the exposure and etching technique well known in the manufacture of semiconductor components. This approach makes it possible to form a slot having 50 μm width, for example.
a shows another example of the antenna component according to the invention. The component 501 is mainly similar to the component 201 presented in
In
The curve 92 shows the fluctuation of the reflection coefficient, when slot between the antenna elements is diagonal according to
The curve 93 shows the fluctuation of the reflection coefficient, when slot between the antenna elements is devious according to
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 |
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20040892 | Jun 2004 | FI | national |
20041088 | Aug 2004 | FI | national |
PCT/FI2005/050089 | Mar 2005 | FI | national |
This application is a continuation of and claims priority to International PCT Application No. PCT/FI2005/050247 having an international filing date of Jun. 28, 2005, which claims priority to Finland Patent Application No. 20040892 filed Jun. 28, 2004, and also to Finland Patent Application No. 20041088 filed Aug. 18, 2004, each of the foregoing incorporated herein by reference in its entirety. This application also claims priority to PCT Application No. PCT/FI2005/050089 having an international filing date of Mar. 16, 2005, also 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 “Multi-band 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/______ filed contemporaneously herewith and entitled “Chip Antenna Apparatus and Methods” {Attorney Docket No. LKP.005A/OP101356US}, also incorporated herein by reference in its entirety.
Number | Date | Country | |
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Parent | 11648429 | Dec 2006 | US |
Child | 12871841 | US | |
Parent | PCT/FI2005/050247 | Jun 2005 | US |
Child | 11648429 | US |