Dual-band antenna

Abstract

A dual-band antenna that allows each frequency band to be independently optimized by adjusting the size of the antenna elements. For example, the antenna can have two different drivers, one for the high frequency and one for the low frequency. By using elements that are orthogonally connected to the low frequency driver, the low frequency driver can act as a reflector for the high frequency driver and low frequency driver without affecting the performance of the antenna in the high frequency. The antenna can also have parasitic elements. For example, parasitic directors parallel to the high band driver can be configured to improve performance in the high band. Additional pairs of parasitic directors can be orthogonally connected to these directors. The size of these pairs can be adjusted to improve performance in the low band while having minimal impact on performance in the high band.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application 16 / 727631, filed December 26, 2019, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to antennas for wireless receiving or transmitting systems, including wireless microphones, Wi-Fi applications, or cellular phones. Background Technology

[0004] Modern wireless communication networks often require devices to operate in multiple frequency bands. For example, wireless local area networks (WLANs) using the Wi-Fi standard typically utilize the 2.4 GHz and 5 GHz bands. Each of these bands will have a certain width, for example, between 100 MHz and 150 MHz. As these networks become larger, several problems emerge. For example, long cables running between non-wireless network devices attenuate the signal when it is being received at or from a wireless device. As another example, the signal of wireless transmission is attenuated due to obstructed areas and interference from nearby sources, such as other Wi-Fi networks, computers, or products operating in the same frequency band. To overcome these problems, antennas with high gain are often used; gain is a measure of the antenna's directivity and electrical efficiency. However, current examples of antennas used for dual-band applications (e.g., printed dipole antennas or slotted monopole antennas) have omnidirectional radiation patterns. Conversely, many directional dual-band antennas are optimized for one band at the expense of the other. Therefore, a directional dual-band antenna optimized for each frequency band is needed. Summary of the Invention

[0005] The following is a simplified overview of this disclosure to provide a basic understanding of some aspects of it. This overview is not a comprehensive summary of this disclosure. It is not intended to identify key or essential elements of the invention or to depict the scope of the invention. The following overview presents only some concepts of the disclosure in a simplified form as a prelude to the more detailed description provided below.

[0006] Various aspects of this disclosure relate to an antenna for a wireless system operating in two different frequency bands, including industrial, scientific, and medical (ISM) radio bands such as those used for Wi-Fi or cellular phones. The frequency bands may also include ultra-high frequency (UHF) bands and bands used for digital enhanced cordless telecommunications (DECT).

[0007] According to another aspect of the disclosure, the performance in each frequency band of the dual-band antenna can be optimized independently. For example, by adjusting the size of certain elements of the antenna based on the frequency of interest, the performance of the antenna can be improved in one frequency band while having minimal impact on the performance of the antenna in another frequency band.

[0008] According to another aspect of the disclosure, the antenna can be designed to operate in two different frequency bands while only requiring a single feed line. This allows the wireless device to operate in two different frequency bands with a single antenna.

[0009] According to another aspect of the disclosure, the antenna can be designed to be passive, meaning that the antenna does not have any components that require a power source. This allows the wireless device with a transceiver to use a single antenna and change between transmission and reception without requiring any electronic switching. BRIEF DESCRIPTION OF DRAWINGS

[0010] A more complete understanding of the present disclosure and its advantages will be obtained by referring to the following description taken in conjunction with the accompanying drawings, in which like reference characters indicate like features, and wherein:

[0011] Figure 1A A schematic diagram illustrating a top view of an example antenna according to one aspect of the disclosure is shown;

[0012] Figure 1B A schematic diagram illustrating a bottom view of the example antenna of Figure 1A

[0013] Figure 2 A schematic diagram illustrating a top view of another example antenna according to one aspect of the disclosure is shown;

[0014] Figure 3 A graph illustrating the voltage standing wave ratio of the example antenna of Figure 1A

[0015] Figure 4A A polar plot graph illustrating the example antenna of Figure 1A

[0016] A polar plot graph illustrating the example antenna of Figure 4B Figure 1A A polar plot graph illustrating the example antenna of

[0017] Figure 5A Figure 1A A radiation pattern graph illustrating the example antenna of

[0018] Figure 5B A radiation pattern graph illustrating the example antenna of Figure 1A DETAILED DESCRIPTION​​​​​

[0019] In the following description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration various examples in which aspects can be practiced. References to "an example," "an implementation," etc., indicate that the example or implementation so described can include a particular feature, structure, or characteristic, but not every example or implementation necessarily includes the particular feature, structure, or characteristic. Some examples or implementations can have some, all, or none of the features described for other examples or implementations. Furthermore, it is contemplated that other examples and / or implementations can be practiced that do not necessarily include every feature described above. Changes can be made in the function and arrangement of elements without departing from the scope of the disclosure.

[0020] The use of successive qualifiers such as "first," "second," "third," etc. to describe an element is used only to indicate a different element of like element, unless otherwise specified. The use of such successive qualifiers does not imply, however, that the elements must be provided in a given order, or that they must be provided in a temporal, spatial, hierarchical, or any other order.

[0021] Also, the terms "front," "back," "side," "top," "bottom," "parallel," "perpendicular," "horizontal," "vertical," and the like can be used in this specification to describe various example features and elements. Such terminology is used for convenience only and is not intended to limit the scope of the disclosure to only those examples described herein. Any use of such terms is based on the example example orientations and / or typical use of such terms in the art, as illustrated in the figures.

[0022] Figure 1A A diagram showing a top view of an example antenna 101 is shown in Figure 1B A diagram showing a bottom view of the same antenna is shown in FIG. 2. The antenna 101 is a printed planar antenna. These types of antennas are typically printed on a printed circuit board (PCB) made of a low-loss dielectric (e.g., FR-4). One advantage of this type of construction is the ability to manufacture antennas that are smaller in size and lower in cost.

[0023] In Figure 1A In the example of FIG. 1, the antenna 101 is symmetric about the x-axis. For clarity, elements with the same number are electrically connected to each other (e.g., 109V and 109H). Elements with the suffix "V" are perpendicular to the x-axis, while elements with the suffix "H" are parallel to the x-axis. Insofar as an element is placed entirely above or below the x-axis (e.g., element 105), a matching element appears on the opposite side of the x-axis. Unless specifically noted, the present description will refer only to the recited element and not to the matching element, but the description applies to both the recited element and its matching element.

[0024] InFigure 1A In this case, the ground structure is partly formed by the conductive elements 105, 107, 108, 109V and 109H. These elements are connected to the shield of the coaxial connector 102 via a main conductive element or main line 108. In this example, the main line 108 is 12.5 mm wide. When the conductive elements or feed lines 103 in the Figure 1B In this case, the ground structure is partly formed by the conductive elements 105, 107, 108, 109V and 109H. These elements are connected to the shield of the coaxial connector 102 via a main conductive element or main line 108. In this example, the main line 108 is 12.5 mm wide. When the conductive elements or feed lines 103 in the Figure 1A The elements of the antenna 101 on the top of the PCB in are separated from the feed line 103 by the thickness of the PCB, which in this example is 1.6 mm. The feed line 103 is connected to the center conductor of the coaxial connector 102. This type of coupling is commonly referred to as a slot coupling and transforms the conductive elements 105, 107, 108, 109V and 109H into driven elements or "drivers". The width of the feed line 103 is determined by the dielectric constant and thickness of the PCB in order to obtain the desired transmission line impedance. In this example, the desired transmission line impedance is 50 Ohms and the feed line 103 is 2.5 mm wide. The "hook" width 104 at the end of the feed line is 6 mm. The gap 106 is the distance across the x-axis between element 107 and its matching element. The size of the gap 106 is optimized to reduce the reactive component of the antenna input impedance. In this example, the gap 106 is 1.5 mm.

[0025] Element 105 and its matching element act as a dipole. Element 105 is the driver element for the high frequency band, which means that this element is responsible for facilitating the reception or transmission of the high frequency band. In this example, if the high frequency band is 5.5 GHz, then element 105 has a length of 11.5 mm and a width of 2.5 mm. Element 107 acts as a transmission line to the feed element 105 and also serves to create a space between elements 105 and 109V. The spacing between elements 105 and 109V is created by the length of element 107. This spacing and the length of element 109V are optimized to allow element 109V to act as a reflector element for the high frequency band element 105, which means that element 109V acts as a mirror to direct the radiated energy of the high frequency band in the direction of the radiation pattern. In part, this reflector element 109V improves the front-to-back ratio (the ratio of the power gain between the front and back lobes of the antenna) and is the way in which the antenna 101 becomes a directional antenna. In this example where the high frequency band is 5.5 GHz, element 107 has a length of 5 mm and a width of 2.5 mm, while element 109V has a length of 18 mm and a width of 2.5 mm.

[0026] Element 109V and its mating element act as a dipole. In addition to acting as a reflector for element 105 in the high frequency band, element 109V also acts as part of the driver element for the low frequency band, in this example the frequency band at 2.4 GHz. Element 109H also acts as part of the driver element for the low frequency band. In this example, element 109H is connected orthogonally to element 109V and has a length of 13.5 mm and a width of 2.5 mm. By adjusting the size of element 109H, the low frequency band performance of antenna 101 can be optimized and improved with minimal impact on performance in the high frequency band.

[0027] In Figure 1A , element 111 is connected to main line 108 to improve the gain and front-to-back ratio of the low frequency band of antenna 101 by acting as a reflector. The length of gap 113 and element 111 maximizes the gain and front-to-back ratio of antenna 101 in the low frequency band while minimally impacting performance in the high frequency band. In this example, element 111 has a length of 20.5 mm and a width of 3.8 mm, while gap 113 is 26 mm. Element 111 is wider than the other elements to improve the front-to-back ratio over a wider bandwidth in the 2.4 GHz frequency band.

[0028] To further improve the front-to-back ratio, it can be desirable to further increase the length of element 111, but size constraints do not allow for such an increase. Figure 2 An alternative embodiment that allows for such a size increase is shown. Specifically, Figure 2 A top view of an alternative embodiment of antenna 101 is shown (similar to Figure 1A ), where like reference numerals indicate like or similar elements. However, in this example, antenna 201 includes element 211H. Element 211H is connected orthogonally to element 211V. This increases the length of element 211V and functionally changes its ability to act as a reflector without increasing the size of the antenna in the y-axis direction.

[0029] Another method of improving the front-to-back ratio of the antenna, as well as the gain of the antenna, includes adding parasitic elements. These parasitic elements, although electrically conductive, are not electrically connected to the driven elements and act to change the radiation pattern of the antenna. In Figure 1A , element 115 is a single electrically conductive element that acts as a director for the high frequency band, thereby improving the gain and front-to-back ratio of antenna 101 in the high frequency band. Here, for the high frequency band of 5.5 GHz, element 115 has a length of 13 mm and is placed 12.5 mm from element 109V (i.e., gap 117). In this example, element 115 has a width of 2.5 mm.

[0030] To further improve the gain and front-to-back ratio of antenna 101, additional parasitic elements can be added, as in Figure 1AElement 119V is a single conductive element that functions as a second high-band director. Element 119V has a length of 12.5 mm and is placed 20 mm from element 109 (i.e., spacing 121). In this example, element 119V has a width of 2.5 mm. Element 119H is connected orthogonally to element 119V. The combined length of elements 119V and 119H is optimized to function as a low-band director, improving the gain and front-to-back ratio of antenna 101 in the low band. Here, for the low band of 2.4 GHz, element 119H has a length of 15 mm and a width of 2.5 mm. The orthogonal nature of 119V and 119H allows each element to be adjusted as needed to highly independently optimize performance for each operating band.

[0031] In Figure 1A , additional parasitic elements 123V, 123H, 127V, and 127H are added to further improve the gain and front-to-back ratio of each band. Element 123V has a length of 15 mm and a width of 6 mm, and is 39.5 mm from element 109V (i.e., spacing 125). In this example, the width of 123V is slightly larger than many of the other elements of antenna 101. The width of an element has less impact on antenna performance, and if an element is too wide, proper spacing between elements can be difficult to achieve. Furthermore, very small widths can both reduce the power handling capability of the antenna and reduce the bandwidth of each operating band. In this example, the width of element 123V is larger than the width of the other elements to improve performance in the 2.4 GHz band, while spacing 125 is set to optimize 5.5 GHz performance. Making element 123V wider helps to optimize operation in the 2.4 GHz band while minimizing the impact in 5.5 GHz. Without this adjustment, spacing 125 would need to be increased to optimize 2.4 GHz performance at the expense of 5.5 GHz operation. Similar to element 119V, element 123V functions as a high-band director. Element 123H is connected orthogonally to element 123V and has a length of 11.5 mm and a width of 2.5 mm. Again, the combined length of 123V and 123H functions as a low-band director, and the orthogonal nature of 123V and 123H allows each element to be adjusted as needed to highly independently optimize the performance of antenna 101 for each operating band.

[0032] Elements 127V and 127H are added to antenna 101 in a functionally similar manner to elements 123V and 123H to improve the gain and front-to-back ratio of each band thereof. Element 127V (again, a high-band director) has a length of 15 mm and a width of 2.5 mm, and is 58.5 mm from element 109V (i.e., spacing 129). Element 127H is connected orthogonally to element 127V and has a length of 15 mm and a width of 2.5 mm. Elements 127H and 127V function as another low-band director.

[0033] Thus, the antenna 101 provides an example of a dual-band directional antenna with single-stage feed that is optimized for frequency, efficiency, gain, and front-to-back ratio for two frequency bands (one band at 2.4 GHz and one band at 5.5 GHz). The horizontal elements (e.g., elements with the suffix "H") allow independent optimization of the lower band while having minimal impact on optimizing the higher band. These horizontal or "bent" elements also make the antenna 101 more compact. Furthermore, the antenna 101 is passive, meaning that it does not require a power source. This allows it to be used in transceiver applications and to change between transmission and reception without the need for electronic switching.

[0034] Figure 3 A voltage standing wave ratio (VSWR) chart for the antenna 101 is illustrated. This chart shows that the antenna 101 has a low amount of power reflected at 2.45 GHz and above 4.75 GHz. By having a low amount of reflected power at these frequencies, this chart indicates that the antenna 101 has been designed to function effectively at these frequencies and at the two frequency bands of interest, 2.45 GHz and 5.5 GHz, meaning that a high percentage of power is transmitted at these frequencies rather than being reflected back at the transmitter.

[0035] Figure 4A and Figure 4B Polar charts for the antenna 101 at 2.45 GHz and 5.775 GHz frequencies are illustrated, respectively. These charts show the theta polarization component of the radiation pattern, as it corresponds to the polarization of the antenna's 101 radiated field. On both frequency bands, the antenna 101 shows strong directivity and little back radiation. This shows that it would be advantageous to use the antenna 101 when a wireless transmitted signal must compete with transmitted signals from other sources, such as other Wi-Fi networks, computers, or products operating in the same frequency band.

[0036] Figure 5A and Figure 5B Radiation patterns for the antenna 101 at 2.45 GHz and 5.775 GHz frequencies are illustrated, respectively. Figure 5A and Figure 5B These radiation patterns show that the antenna 101 can transmit a signal with strong directivity and little back radiation at these two frequencies. These radiation patterns also show that the antenna 101 can be used for wireless networks that require a directional dual-band antenna to overcome shadowed areas and interference from nearby wireless sources.

[0037] While the antenna 101 is designed to cover frequency bands at 2.45 GHz and 5.5 GHz, other embodiments can support different dual frequency bands. For example, some embodiments can support low UHF bands, high UHF bands, and / or cellular bands (e.g., 800 MHz, 900 MHz, 1800 MHz, or 1900 MHz). Thus, some embodiments can support wireless applications other than Wi-Fi, such as wireless microphones, cellular telephones, or cordless telephones. In selecting the frequencies of the frequency bands, the higher frequency bands are generally about twice the frequency of the lower frequency bands. The dimensions of the antenna elements of these different embodiments will depend on the wavelength of the frequency band of interest. Additionally, the performance of the antenna can be altered by chamfering or beveling the ends of the elements.

[0038] Another design consideration for the antenna includes the number and orientation of the parasitic elements used. For example, the horizontal and vertical elements do not necessarily have to be connected orthogonally; however, changing the angle of connection will make changing the dimensions of the elements affect both frequency bands. Alternatively, if the overall size of the antenna is a limiting factor, fewer parasitic elements can be included, such as not including elements 123V, 123H, 127V, and 127H in the antenna 101. Similarly, elements can be added or excluded if one frequency band is more important than the other. For example, if the high frequency band is more important, the horizontal elements of the passive elements (e.g., the elements with the suffix "H" in the antenna 101) can be excluded, allowing the vertical elements to have more influence, which directs the high frequency band.

[0039] In another embodiment, an antenna includes a main conductive element or main wire, a conductive feed element or feed wire, and a first pair of conductive elements or reflectors connected on opposite sides of the main conductive element. The antenna also includes a second pair of conductive elements connected to a first end of the main conductive element. The second pair of conductive elements acts as a first pair of drivers and is parallel to the first pair of conductive elements. The antenna also includes a third pair of conductive elements connected to the second pair of conductive elements away from the main conductive element. The third pair of conductive elements acts as a second pair of drivers and, together with the first pair of drivers, is configured to operate in a first frequency band. The antenna also includes a fourth pair of conductive elements that acts as a transmission line and is connected to the second pair of conductive elements proximate to the main conductive element. The antenna also includes a fifth pair of conductive elements connected to the fourth pair of conductive elements and parallel to the second pair of conductive elements. The fifth pair of conductive elements acts as a third pair of drivers and is configured to operate in a second frequency band. The antenna also includes a first single conductive element that acts as a director and is placed away from the main conductive element and separated by a distance from the fifth pair of conductive elements. The first single conductive element is also parallel to the fifth pair of conductive elements. The antenna also includes a second single conductive element that acts as a second director and is placed separated by a distance from the first single conductive element such that the first single conductive element is between the fifth pair of conductive elements and the second single conductive element. The second single conductive element is also parallel to the first single conductive element. The antenna also includes a sixth pair of conductive elements, where each conductive element of the sixth pair of conductive elements is connected to opposite ends of the second single conductive element. The sixth pair of conductive elements acts as a director.

[0040] Finally, although subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. An antenna, comprising: a main conductive element; a conductive feed element; a first pair of conductive elements connected on opposite sides of the main conductive element; a second pair of conductive elements connected to a first end of the main conductive element, wherein the second pair of conductive elements is parallel to the first pair of conductive elements; a third pair of conductive elements connected to the second pair of conductive elements away from the main conductive element, wherein the second pair of conductive elements and the third pair of conductive elements are configured to operate in a first frequency band; a fourth pair of conductive elements connected to the second pair of conductive elements proximate to the main conductive element; a fifth pair of conductive elements connected to the fourth pair of conductive elements, wherein the fifth pair of conductive elements is parallel to the second pair of conductive elements, and wherein the fifth pair of conductive elements is configured to operate in a second frequency band; a first single conductive element placed away from the main conductive element and separated by a distance from the fifth pair of conductive elements, wherein the first single conductive element is parallel to the fifth pair of conductive elements; a second single conductive element placed separated by a distance from the first single conductive element, wherein the second single conductive element is parallel to the first single conductive element, and wherein the first single conductive element is between the fifth pair of conductive elements and the second single conductive element; a sixth pair of conductive elements, wherein each conductive element of the sixth pair of conductive elements is connected to opposite ends of the second single conductive element, and a plurality of additional conductive elements, wherein each conductive element of the plurality of additional conductive elements comprises an additional single conductive element placed separated by a distance from other conductive elements of the antenna and parallel to the first single conductive element, and an additional pair of conductive elements connected to opposite ends of the additional single conductive element.

2. The antenna of claim 1, further comprising a seventh pair of conductive elements connected to the first pair of conductive elements away from the main conductive element.

3. The antenna of claim 1, wherein the second pair of conductive elements is connected perpendicularly to the third pair of conductive elements.

4. The antenna of claim 3, wherein each conductive element of the sixth pair of conductive elements is connected perpendicularly to opposite ends of the second single conductive element.

5. The antenna of claim 1, wherein each conductive element of the additional pair of conductive elements is connected perpendicularly to opposite ends of the additional single conductive element.

6. The antenna of claim 2, wherein each conductive element of the seventh pair of conductive elements is connected perpendicularly to the first pair of conductive elements.

7. A method of manufacturing an antenna, comprising: manufacturing the antenna to comprise: a main conductive element; a conductive feed element; a first pair of conductive elements connected on opposite sides of the main conductive element; a second pair of conductive elements connected to a first end of the main conductive element, wherein the second pair of conductive elements is parallel to the first pair of conductive elements; a third pair of electrically conductive elements connected to the second pair of electrically conductive elements away from the main electrically conductive element, wherein the second pair of electrically conductive elements and the third pair of electrically conductive elements are configured to operate in a first frequency band; a fourth pair of electrically conductive elements connected to the second pair of electrically conductive elements proximate to the main electrically conductive element; a fifth pair of electrically conductive elements connected to the fourth pair of electrically conductive elements, wherein the fifth pair of electrically conductive elements is parallel to the second pair of electrically conductive elements, and wherein the fifth pair of electrically conductive elements is configured to operate in a second frequency band; a first single electrically conductive element placed away from the main electrically conductive element and separated by a distance from the fifth pair of electrically conductive elements, wherein the first single electrically conductive element is parallel to the fifth pair of electrically conductive elements; a second single electrically conductive element placed separated by a distance from the first single electrically conductive element, wherein the second single electrically conductive element is parallel to the first single electrically conductive element, and wherein the first single electrically conductive element is between the fifth pair of electrically conductive elements and the second single electrically conductive element; a sixth pair of electrically conductive elements, wherein each electrically conductive element of the sixth pair of electrically conductive elements is connected to opposite ends of the second single electrically conductive element, and a plurality of additional electrically conductive elements, wherein each electrically conductive element of the plurality of additional electrically conductive elements comprises an additional single electrically conductive element placed separated by a distance from other electrically conductive elements of the antenna and parallel to the first single electrically conductive element, and an additional pair of electrically conductive elements connected to opposite ends of the additional single electrically conductive element.

8. The method of claim 7, wherein the antenna further comprises a seventh pair of electrically conductive elements connected to the first pair of electrically conductive elements away from the main electrically conductive element.

9. The method of claim 7, wherein the second pair of electrically conductive elements is connected perpendicularly to the third pair of electrically conductive elements.

10. The method of claim 9, wherein each electrically conductive element of the sixth pair of electrically conductive elements is connected perpendicularly to opposite ends of the second single electrically conductive element.

11. The method of claim 7, wherein each electrically conductive element of the additional pair of electrically conductive elements is connected perpendicularly to opposite ends of the additional single electrically conductive element.

12. The method of claim 8, wherein each electrically conductive element of the seventh pair of electrically conductive elements is connected perpendicularly to the first pair of electrically conductive elements.

13. An antenna, comprising: a main line; a feed line; a pair of reflectors connected on opposite sides of the main line; a first pair of drivers connected to a first end of the main line, wherein the first pair of drivers is parallel to the pair of reflectors; a second pair of drivers connected to the first pair of drivers away from the main line, wherein the first pair of drivers and the second pair of drivers are configured to operate in a first frequency band; a pair of transmission lines connected to the first pair of drivers proximate to the main line; a third pair of drivers connected to the pair of transmission lines, wherein the third pair of drivers is parallel to the first pair of drivers, and wherein the third pair of drivers is configured to operate in a second frequency band; a first director placed a distance away from the main wire and separate from the third pair of drivers, wherein the first director is parallel to the third pair of drivers; a second director placed a distance away from the first director, wherein the second director is parallel to the first director, and wherein the first director is between the third pair of drivers and the second director; and a pair of directors, wherein each director of the pair of directors is connected to opposite ends of the second director.

14. The antenna of claim 13, further comprising a plurality of additional directors, wherein each director of the plurality of additional directors comprises: an additional director placed a distance away from other conductive elements of the antenna, wherein the additional director is parallel to the first director; and an additional pair of directors connected to opposite ends of the additional director.

15. The antenna of claim 14, wherein the first, second, and additional directors are configured to operate in the second frequency band.

16. The antenna of claim 15, wherein the pair of directors and the additional pair of directors are configured to operate in the first frequency band.

17. The antenna of claim 16, wherein the first frequency band and the second frequency band correspond to frequency bands used by devices on a Wi-Fi network.

18. The antenna of claim 14, wherein the plurality of additional directors comprises at least two additional directors.

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