Multi-element antenna for multiple bands of operation and method therefor

Abstract

An antenna assembly has a conductive line coupled to a feed point. An element is configured to resonate at a predetermined frequency. The element is electrically coupled to the conductive line and aligned perpendicular to the conductive line wherein the predetermined frequency of the element determines a distance from the feed point along the conductive line.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

Field of the Invention

The present application generally relates to antennas, and more specifically to a multi-element antenna in which each element is orthogonal to a conductive line being fed by a transmission line to provide for multiple working frequencies.

Description of the Related Art

More and more electronic devices are being designed with wireless communication capabilities. These devices, such as portable computers, smartphones, tablets, smart watches and other handheld electronic may be provided with long-range wireless communications circuitry such as cellular telephone circuitry and/or short-range communications circuitry such as wireless local area network communications circuitry. Some of the aforementioned devices may be provided with the ability to receive other wireless signals such as Global Positioning System (GPS) signals.

Antenna design may be difficult since the antenna has to satisfy a plurality of different requirements related to geometry, electrical performance, efficiency as well as other requirements. For example, with electronic devices becoming smaller in size, the space available for the antennas may be limited. In many electronic devices, the presence of electronic components of the electronic device may be a source of electromagnetic interference for the antenna. Antenna operation may also be disrupted by nearby conductive structures. Considerations such as these can make it difficult to implement an antenna in an electronic device.

These issues maybe compounded in applications where the antenna may need to operate in multiple bands. For example, cellular telephone networks and WIFI Internet connections are commonly used for communication with portable electronic devices. Cellular telephones transmit in the 824 to 845 MHz frequency band and receive signals in the 870 to 896 MHz frequency band. PCS telephones operate in the 1850 to 1990 MHz. frequency band. The WIFI protocol enables communication over different frequency bands, for example the 2.4 GHz ISM band and the 5.0 GHz U-NII band. An antenna that is tuned to operate with one of these frequency bands is not optimum for communication in another frequency band.

Therefore, it would be desirable to provide a system and method that overcomes the above.

BRIEF SUMMARY OF THE INVENTION

In accordance with one embodiment, an antenna assembly is disclosed. The antenna assembly has a conductive line coupled to a feed point. An element is configured to resonate at a predetermined frequency. The element is electrically coupled to the conductive line and aligned perpendicular to the conductive line wherein the predetermined frequency of the element determines a distance from the feed point along the conductive line.

In accordance with one embodiment, an antenna assembly is disclosed. The antenna assembly has a first substrate. An opening is formed in a central area of the first substrate. A first conductive line is formed on a first surface of the first substrate and runs down a length of the first substrate. A transmission line is positioned through the opening and is electrically coupled to the first conductive line. A first plurality of pairs of elements is provided. Each pair of the first plurality of pairs of elements resonates at different predetermined frequencies in a first frequency bandwidth. Each of the first plurality of pairs of elements has a first member and a corresponding member, wherein each of the first plurality of pairs of elements is electrically coupled to the first conductive line and aligned perpendicular to the first conductive line. The first member of each the first plurality of pairs of elements is positioned on a first side of the feed point along the length of the first substrate and the corresponding member of each of the first plurality of pairs of elements is positioned on an opposing side of the feed point along the length of the first substrate, the different predetermined frequencies determining a distance from the feed point along the first conductive line for each of the first plurality of pairs elements.

In accordance with one embodiment, an antenna assembly is disclosed. The antenna assembly has a first substrate. An opening is formed in a central area of the first substrate. A first conductive line is formed on a first surface of the first substrate and runs down a length of the first substrate. A transmission line is positioned through the opening and electrically coupled to the first conductive line. A first plurality of pairs of elements is provided, each pair of the first plurality of pairs of elements resonating at different predetermined frequencies in a first frequency bandwidth. Each of the first plurality of pairs of elements has a first member and a corresponding member, wherein each of the first plurality of pairs of elements is electrically coupled to the first conductive line and aligned perpendicular to the first conductive line. The first member of each of the first plurality of pairs of elements is positioned on a first side of the feed point along the length of the first substrate and the corresponding member of each of the first plurality of pairs of elements is positioned on an opposing side of the feed point along the length of the first substrate. The different predetermined frequencies determine a distance from the feed point along the first conductive line for each of the first plurality of pairs of elements. A second substrate is positioned perpendicular to the first substrate and runs down the length of the first substrate. The first plurality of pairs of elements is attached to the second substrate.

Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a prospective view of an antenna assembly in accordance with one aspect of the present application.

FIG. 2 is a cross-sectional view of the antenna assembly of FIG. 1 in accordance with one aspect of the present application.

FIG. 3 is a prospective view of an antenna assembly in accordance with one aspect of the present application.

FIG. 4 is a side view of the antenna system of FIG. 4 in accordance with one aspect of the present application.

DETAILED DESCRIPTION OF THE INVENTION

The description set forth below in connection with the appended drawings is intended as a description of presently preferred embodiments of the disclosure and is not intended to represent the only forms in which the present disclosure can be constructed and/or utilized. The description sets forth the functions and the sequence of steps for constructing and operating the disclosure in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and sequences can be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of this disclosure.

Referring to FIGS. 1 and 2, an antenna assembly 10 according with one aspect of the present invention is shown. The antenna assembly 10 may be used for bidirectional and/or unidirectional communications. The antenna assembly 10 may be formed of a substrate 12. The substrate 12 may be formed of a non-conductive material such as, but not limited to a phenolic plastic impregnated type of paper, fiberglass mats in an epoxy, Teflon/plastic sheet or similar material. One or more conductive lines 14 may be formed on a first surface 12A of the substrate 12. In the present embodiment, two conductive lines 14A and 14B may be seen. However, this is shown as an example and should not be seen in a limiting manner. The conductive lines 14 may be formed of metals such as copper, brass or the like applied on the surface 12A. In accordance with one embodiment, the conductive lines 14 may be a microstrip. The conductive lines 14 may be configured to provide an impedance at a desired level as will be disclosed below.

An opening 16 may be formed through the substrate 12. The opening 16 may be used to electrically couple a first end of a coaxial cable 18 to the conductive lines 14. A second end of the coaxial cable 18 may be coupled to a communication circuit such as a receiver and/or transceiver. A coaxial cable 18 may be coupled to each of the conductive lines 14. Thus, in the present embodiment, a coaxial cable 18A may be coupled to the conductive lines 14A and a coaxial cable 18B may be coupled to the conductive lines 14B. A coupling 20 may be used to electrically couple the coaxial cables 18 to the conductive lines 14.

As stated above, the conductive lines 14 may be configured to provide a desired impedance. The desired impedance may be based on an impedance level of the coaxial cable 18. In accordance with one embodiment, a line width of the conductive line 14 may be designed to provide an impedance level approximately equal to the coaxial cable 18 coupled to the conductive line 14. Thus, for example, the conductive line 14 may be configured to provide an impedance of 50.OMEGA. to approximately match the impedance of coaxial cable for RE applications.

One or more antenna elements 22 may be electrically coupled to the conductive lines 14. Each element 22 may be aligned perpendicular to the conductive line 14. Each element 22 may be size to resonate at a desired predetermine frequency. By providing a plurality of elements 22, the antenna assembly 10 may operate at multiple frequencies.

Each of the elements 22 may require proper placement along the conductive line 14. Impedance issues may arise if the elements 22 are not properly positioned along the conductive line 14. There is a correlation between the location of the element 22 on the conductive line 14 and wavelength. The position and length of the elements 22 may be dependent on the dielectric material of the substrate 12, the frequency the element 22 resonates at, and the like.

The elements 22 may be positioned in a descending order from a feed point 20A of the conductive line 14 on which the element 22 is located. Thus, elements 22 resonating at a higher frequency may be positioned on the conductive line 14 closer to the feed point 20A than an element 22 resonating at a lower frequency. Thus, if multiple elements 22 are placed on the conductive line 14, the element 22 resonating at the lowest frequency may be positioned furthest from the feed point 20A, while the element resonating at the highest frequency may be positioned closest to the feed point 20A. Again, the exact location of each element 22 on the conductive line 14 may vary based on the above factors.

For example, in FIGS. 1-2, three pairs of elements 22 may be seen wherein the first pair may be comprised of elements 22A and 22A′, the second pair may be comprised of elements 22B and 22W and the third pair may be comprised of elements 22C and 22C′. The elements 22A, 22B and 22C may be positioned on the conductive line 14A while the corresponding elements 22A′, 223 and 22C′ may be positioned on the conductive line 14B. In this example, the elements 22A and 22A′ may resonate at a frequency of 800 MHz, the elements 22B and 223 may resonate at a frequency of 1600 MHz and the elements 22C and 22C′ may resonate at a frequency 2400 MHz. Since the elements 22A and 22A′ resonate at the lowest frequency, the elements 22A and 22A′ may be located furthest from the feed point 22A. If the conductive lines 14A and 14B are approximately the same length, the elements 22A and 22A′ may be located approximately equal distance from the feed point 22A. The elements 22C and 22C′ resonates at the highest frequency, which is approximately three times the frequency of the elements 22A and 22A′, may be positioned closest to the feed point 20A. If the conductive lines 14A and 14B are approximately the same length, the elements 22B and 22W may be located approximately equal distance from the feed point 22A. The elements 22B and 223, which resonates at two times the frequency of the elements 22A and 22A′, may be located in the middle such that element 22B may be positioned in between the elements 22A and 22C and element 22B′ may be positioned in between the elements 22A′ and 22C′. If the conductive lines 14A and 14B are approximately the same length, the elements 22C and 22C′ may be located approximately equal distance from the feed point 22A.

In accordance with one embodiment, the elements 22 may be planer elements instead of lumped elements. The planer elements may be microstrips 24. The microstrips 24 may be placed on a substrate 26. The substrate 26 may be coupled to the substrate 12 to electrically couple the microstrips 24 to the conductive line 14 and to keep the microstrips 24 approximately orthogonal to the conductive line 14. As may be seen in FIGS. 1-2, the elements 22A, 22B and 22C may be positioned on a first side 26A of the substrate 26 and attached to the conductive line 14A while the corresponding elements 22A′, 22B′ and 22C′ may be positioned on a second side 26B of the substrate 26 and attached to the conductive line 14B.

A cover 28 may be positioned over the elements 22 and attached to the substrate 12. The cover 28 may be used to prevent damage to the elements 22.

Referring to FIGS. 3-4, an antenna assembly 10′ according with one aspect of the present invention is shown. The antenna assembly 10′ may be used for bidirectional and/or unidirectional communications. In the present embodiment, the antenna assembly 10′ may be a dual band antenna assembly. Thus, the antenna assembly 10′ may allow communication in multiple frequency bands such as WiFi and cellular or other combinations of frequency bands. The above is given as an example and should not be seen in a limiting manner. Other frequency bands may be used without departing from the spirit and scope of the present invention.

The antenna assembly 10′ may be formed of a substrate 12. The substrate 12 may be formed of a non-conductive material such as, but not limited to a phenolic plastic impregnated type of paper, fiberglass mats in an epoxy, Teflon/plastic sheet or similar material. One or more conductive lines 14 may be formed on a surface 12A of the substrate 12. In the present embodiment, four conductive lines 14A-14D may be seen. However, this is shown as an example and should not be seen in a limiting manner. The conductive lines 14 may be formed of metals such as copper, brass or the like applied on the surface 12A. In accordance with one embodiment, the conductive lines 14 may be a microstrip. The conductive lines 14 may be configured to provide an impedance at a desired level as will be disclosed below.

An opening 16 may be formed through the substrate 12. The opening 16 may be used to electrically couple a first end of a coaxial cable 18 (FIG. 2) to the conductive lines 14. A second end of the coaxial cable 18 may be coupled to a communication circuit such as a receiver/transceiver. As in the previous embodiment, a different coaxial cable 18 may be coupled to each of different conductive lines 14. Thus, in the present embodiment, different coaxial cables 18 may be coupled to each of the conductive lines 14A-14D. In accordance with one embodiment, a coupling 20 (FIG. 2) may be used to electrically couple the coaxial cable 18 to the conductive lines 14.

As stated above, the conductive lines 14 may be configured to provide a desired impedance. The desired impedance may be based on an impedance level of the coaxial cable 18. In accordance with one embodiment, a line width of the conductive line 14 may be designed to provide an impedance level approximately equal to the coaxial cable 18 coupled to the conductive line 14. Thus, for example, the conductive line 14 may be configured to provide an impedance of 50 ohms to approximately match the impedance of coaxial cable for RF applications.

One or more antenna elements 22 may be electrically coupled to the conductive lines 14. Each element 22 may be aligned perpendicular to the conductive line 14. Each element 22 may be size to resonate at a desired predetermine frequency. By providing a plurality of elements 22, the antenna assembly 10′ may operate at multiple frequencies at multiple bands of operation.

Each of the elements 22 may require proper placement along the conductive line 14. Impedance issues may arise if the elements 22 are not properly positioned along the conductive line 14. There is a correlation between the location of the element 22 on the conductive line 14 and wavelength. The position and length of the elements 22 may be dependent on the dielectric material of the substrate 12, the frequency the element 22 resonates at, and the like.

The elements 22 may be positioned in a descending order from a feed point 20A of the conductive line 14 on which the element 22 is located. Thus, elements 22 resonating at a higher frequency may be positioned on the conductive line 14 closer to the feed point 20A than an element 22 resonating at a lower frequency. Thus, if multiple elements 22 are placed on the conductive line 14, the element 22 resonating at the lowest frequency may be positioned furthest from the feed point 20A, while the element resonating at the highest frequency may be positioned closest to the feed point 20A. Again, the exact location of each element 22 on the conductive line 14 may vary based on the above factors.

For example, in FIGS. 3-4, five pairs of elements 22 may be seen, wherein three pairs of elements 22 may be located along a length of the substrate 12 and may operate in a first frequency band range and two pairs of elements 22 may be located along a width of the substrate 12 and may operate in a second frequency band range. The first pair may be comprised of elements 22A and 22A′, the second pair may be comprised of elements 22B and 223, the third pair may be comprised of elements 22C and 22C′, the fourth pair may be comprised of elements 22D and 22D′ and the fifth pair may be comprised of elements 22E and 22E′.

The elements 22A, 22B and 22C may be positioned on the conductive line 14A while the corresponding elements 22A′, 22W and 22C′ may be positioned on the conductive line 14B and resonate in the first frequency band range. In this example, the elements 22A and 22A′ may resonate at a frequency of 800 MHz, the elements 22B and 22W may resonate at a frequency of 1600 MHz and the elements 22C and 22C′ may resonate at a frequency 2400 MHz. Since the elements 22A and 22A′ resonate at the lowest frequency, the elements 22A and 22A′ may be located furthest from the feed point 22A. If the conductive lines 14A and 14B are approximately the same length, the elements 22A and 22A′ may be located approximately equal distance from the feed point 22A. The elements 22C and 22C′ resonates at the highest frequency, which is approximately three times the frequency of the elements 22A and 22A′, may be positioned closest to the feed point 20A. If the conductive lines 14A and 14B are approximately the same length, the elements 22B and 22W may be located approximately equal distance from the feed point 22A. The elements 22B and 22W, which resonates at two times the frequency of the elements 22A and 22A′, may be located in the middle such that element 22B may be positioned in between the elements 22A and 22C and element 22W may be positioned in between the elements 22A′ and 22C′. If the conductive lines 14A and 14B are approximately the same length, the elements 22C and 22C′ may be located approximately equal distance from the feed point 22A.

The elements 22D and 22E may be positioned on the conductive line 14C while the corresponding elements 22D′ and 22E′ may be positioned on the conductive line 14D and resonate in the second frequency band range. In this example, the elements 22D and 22D′ may resonate at a frequency of 2.4 GHz and the elements 22E and 22E′ may resonate at a frequency of 3.6 GHz. Since the elements 22D and 22D′ resonate at the lowest frequency, the elements 22D and 22D′ may be located furthest from the feed point 22A. If the conductive lines 14C and 14D are approximately the same length, the elements 22D and 22D′ may be located approximately equal distance from the feed point 22A. The elements 22E and 22E′ resonates at the highest frequency, which is approximately 1.5 times the frequency of the elements 22D and 22D′, may be positioned closest to the feed point 20A. If the conductive lines 14C and 14D are approximately the same length, the elements 22E and 22E′ may be located approximately equal distance from the feed point 22A.

In accordance with one embodiment, the elements 22 may be planer elements instead of lumped cements. The planer elements may be microstrips 24. The microstrips 24 may be placed on substrates 26 and 30. The substrates 26 and 30 may be coupled to the substrate 12 to electrically couple the microstrips 24 to the conductive line 14 and to keep the microstrips 24 approximately orthogonal to the conductive line 14. As may be seen in FIGS. 3-4, the elements 22A, 22B and 22C may be positioned on a first side 26A of the substrate 26 and attached to the conductive line 14A while the corresponding elements 22A′, 223 and 22C′ may be positioned on a second side 26B of the substrate 26 and attached to the conductive line 14B. The elements 22D and 22E may be positioned on a first side 30A of the substrate 30 and attached to the conductive line 14C while the corresponding elements 22D′ and 22E′ may be positioned on a second side 30B of the substrate 30 and attached to the conductive line 14D.

A cover 28 (FIG. 2) may be positioned over the elements 22 and attached to the substrate 12. The cover 28 may be used to prevent damage to the elements 22.

From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes modification and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claim. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.

Claims

1. A multi-element antenna assembly comprising: a first substrate;a second substrate orthogonal to the first substrate;an opening formed in a central area of the first substrate;a first conductive line formed on a first surface of the first substrate;a second conductive line formed on the first surface of the first substrate;a first transmission line positioned through the opening and electrically coupled to the first conductive line and the second conductive line at a feed point; anda first plurality of elements positioned on the second substrate, the first plurality of elements having at least a highest frequency member and a corresponding highest frequency member and a lowest frequency member and a corresponding lowest frequency member, each of the highest frequency member and the corresponding highest frequency member resonating at different predetermined frequencies than the lowest frequency member and the corresponding lowest frequency member, wherein the frequency member of the first plurality of elements is electrically coupled to the first conductive line and the corresponding highest frequency member of the first plurality of elements is electrically coupled to the second conductive line, wherein the highest frequency member of the first plurality of elements is positioned at a first point a first distance from the feed point and the corresponding highest frequency member of the first plurality of elements is positioned at a second point a first distance from the feed point;wherein the different predetermined frequencies determine a distance from the feed point along the first conductive line and the second conductive line for each of the first plurality of elements.

2. The multi-element antenna assembly according to claim 1 wherein the highest frequency element of the first plurality of elements operates at 2400 MegaHertz (MHz).

3. The multi-element antenna assembly according to claim 1 wherein a second highest frequency element of the first plurality of elements operates at 1600 MHz.

4. The multi-element antenna assembly according to claim 1 wherein the lowest frequency element of the first plurality of elements operates at 800 MHz.

5. The multi-element antenna assembly according to claim 1, further comprising: a third substrate orthogonal to the first substrate;a third conductive line formed on a second surface of the first substrate;a fourth conductive line formed on the second surface of the first substrate;a second transmission line positioned through the opening and electrically coupled to the third conductive line and the fourth conductive line at a second feed point; and a second plurality of elements positioned on the third substrate, the second plurality of elements having at least a highest frequency member and a corresponding highest frequency member and a lowest frequency member and a corresponding lowest frequency member, each of the highest frequency member and the corresponding highest frequency member of the second plurality of elements resonating at a same predetermined frequency, wherein the highest frequency member of the second plurality of elements is electrically coupled to the third conductive line and the corresponding highest frequency member of the second plurality of elements is electrically coupled to the fourth conductive line, wherein the highest frequency member of the second plurality of elements is positioned at a third point a third distance from the second feed point and the corresponding highest frequency member of the second plurality of elements is positioned at a fourth point the third distance from the feed point.

6. The multi-element antenna assembly according to claim 5, wherein each first member and corresponding member of the first plurality of elements are microstrips placed on the second substrate and each first member and corresponding member of the second plurality of elements are microstrips placed on the third substrate.

7. The multi-element antenna assembly according to claim 1, wherein the first conductive line is configured to have a first impedance and the second conductive line is configured to have a second impedance.

8. The multi-element antenna assembly according to claim 7, wherein the first impedance and the second impedance are determined at least in part by an impedance of the first transmission line.

9. The multi-element antenna assembly according to claim 8, wherein the first impedance and the second impedance are substantially equal to the impedance of the first transmission line.

10. A multi-element antenna assembly comprising: a first substrate;a second substrate orthogonal to the first substrate;an opening formed in a central area of the first substrate;a first conductive line formed on a first surface of the first substrate;a second conductive line formed on the first surface of the first substrate;a first transmission line positioned through the opening and electrically coupled to the first conductive line and the second conductive line at a feed point; anda first plurality of elements positioned on the second substrate, each of the first plurality of elements having at least a highest frequency member and a corresponding highest frequency member and a lowest frequency member and a corresponding lowest frequency member, wherein the highest frequency member of the first plurality of elements is electrically coupled to the first conductive line and the corresponding highest frequency member of the first plurality of elements is electrically coupled to the second conductive line, wherein the highest frequency member of the first plurality of elements is positioned at a first point a first distance from the feed point and the corresponding highest frequency member of the first plurality of elements is positioned at a second point the first distance from the feed point;wherein each of the elements of the first plurality of elements is positioned in descending order with a highest frequency element of the first plurality of elements located closest to the feed point and a lowest frequency element of the first plurality of elements located furthest from the feed point.

11. The multi-element antenna assembly according to claim 10 wherein the highest frequency element of the first plurality of elements operates at 2400 MegaHertz (MHz).

12. The multi-element antenna assembly according to claim 10 wherein a second highest frequency element of the first plurality of elements operates at 1600 MHz.

13. The multi-element antenna assembly according to claim 10 wherein the lowest frequency element of the first plurality of elements operates at 800 MHz.