Antenna Structure

Abstract

An antenna structure for radiating radio frequency signals, the antenna structure including a conductive element having a rim with a rim edge and a gap, a wire antenna element positioned to extend parallel to the rim edge and thereby partially overlap the rim and partially overlap the gap, the rim edge being electromagnetically exposed in the assembled and ready-to-operate state of the antenna structure, and the wire antenna element being configured such that radio frequency currents flowing or induced through the wire antenna element induce electric fields at the overlapping portion of the rim and the edge of the gap, causing the electromagnetically exposed rim edge and the edge of the gap in the overlapping portion of the rim to radiate radio frequency signals in response to the radio frequency currents.

Description

[Technical Field]

[0001] The present invention relates to the field of antenna design. [Background technology]

[0002] Antenna structures are widely used in the field of radio frequency communications to radiate and receive radio frequency signals, and in particular to enable transceivers to communicate with other devices that also have antenna structures.

[0003] There is growing interest in developing compact antenna structures, such as those that can fit within the housing or casing of a lighting fixture. Such use case scenarios present significant challenges because the presence of the housing or casing, and the conductive elements (e.g., heat sinks or heat spreaders) inherent in such devices, can significantly affect the efficiency of the antenna structure.

[0004] Standard radio frequency (RF) boards with a Planar Inverted-F antenna (PIFA) printed on the board are widely used in the industry. However, such RF boards cannot fit into the housing of small lamps, such as MR16 lamps. Another disadvantage of using such standard RF boards in lamps is that the metal housing / heat sink of the lamp and the external metal parts of the luminaire can interfere with the RF performance of the antenna.

[0005] It is also known to cut a slot in the lamp's heat sink, with a length corresponding to 1 / 2 or 1 / 4 of the lambda (λ) of the desired / target RF signal, and place an RF radiator in the heat sink near the slot to induce an electric field in the slot, causing the slot to emit RF emissions externally. Lambda (λ) represents the wavelength of the desired RF signal. This requires a large heat sink to form the slot, and the slot can adversely affect the heat dissipation of the heat sink. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, it is desirable to design an antenna structure that can provide high efficiency within the confined space surrounded by the blocking elements present in the lamp.

[0007] US20160183353A1 discloses a light valve with an aperture antenna.

[0008] US20160072176A1 discloses a light valve with a slot antenna. [Means for solving the problem]

[0009] The invention is defined by the claims.

[0010] The proposed invention overcomes the above-mentioned problems by using a conductive element to supplement the wire antenna element to improve the radiation of radio frequency signals. It is recognized that, inter alia, by positioning the wire antenna element near the rim of the conductive element and configuring the rim to provide a slot or gap, such that the wire antenna at least partially overlaps this slot or gap, the rim, including the gap, of the conductive element will radiate the radio frequency signals. The efficiency of such an antenna structure will be much higher than a simple wire antenna element alone, especially when the antenna structure is surrounded by a housing / casing.

[0011] The gap is formed in the edge of the rim, for example, so that it is effectively a cut-out or indentation from the edge of the rim. The gap effectively expands the contour length of the rim (e.g., the total length or size of the edge) along which the wire antenna induces an electric field, allowing the conductive element to use two dimensions to provide the required length, for example, corresponding to ½ or ¼ of lambda (λ). Therefore, the proposed invention can fit into small-sized applications or devices, such as lamps.

[0012] The conductive element can be an existing conductive element inherent to the electronic device, such as a heat sink or heat spreader of the electronic device. This allows existing elements or features to be repurposed to perform a secondary function, thereby improving the efficiency of the antenna structure without significantly affecting the existing functionality of the electronic device containing the antenna structure and / or without requiring additional components (and therefore additional material costs). Furthermore, because the gap forms only a portion of the length, its depth can be small relative to a pure slot antenna. Thus, the proposed embodiment does not significantly affect the heat dissipation capability of the heat sink.

[0013] According to an example according to one aspect of the present invention, there is provided an antenna structure including: a conductive component having a first rim portion with a rim edge and a rim including a gap adjacent to the first rim portion; and a wire radiation element electrically insulated from the conductive component, the wire radiation element including a first wire portion spatially aligned with and extending parallel to the rim edge of the first rim portion and a second wire portion spanning a portion of the gap. The rim edge is electromagnetically exposed in the assembled and ready to operate state of the antenna structure, and the wire radiating element is configured to induce an electric field within the first rim portion and the edge of the gap when supplied with a radio frequency current, causing the electromagnetically exposed rim edge of the first rim portion and the edge of the gap to radiate a radio frequency signal responsive to the radio frequency current supplied to the wire radiating element.

[0014] In the proposed approach, a gap on the conductive element is designed such that the portion of the conductive element near the gap (including at least the first rim portion) becomes the main radiator of the antenna, which acts to decouple the radiating location from the wire antenna element, thereby allowing the radiating location to be distanced from the casing or housing of the antenna structure.

[0015] Inducing an electric field in the first rim portion and the gap effectively induces current flow through the boundaries of the conductive elements at the surface of the first rim portion and in the gap, and this induced surface current causes these elements to radiate energy in the form of electromagnetic waves (i.e., radio frequency signals).

[0016] Contrary to known applications where the antenna is placed under and blocked by the conductive element (heat sink), the present application effectively uses the rim of the conductive element as an antenna, and the efficiency of the proposed antenna structure is significantly higher and less sensitive to the conductive element, which can also be used for other functions such as heat spreading, thereby facilitating more compact electronic devices.

[0017] In some examples, the length of the wire radiating element aligned with and extending parallel to the rim edge plus the contour length of the gap corresponds to the desired wavelength of the radio frequency signal, and preferably the length of the wire radiating element aligned with and extending parallel to the rim edge plus the contour length of the gap is equal to 1 / 2 of the desired wavelength of the radio frequency signal.

[0018] The contour length of the gap is the total length along the sides of the gap that contributes to the portion of the rim where an electric field is induced by the antenna, thereby generating or emitting a radio frequency signal.

[0019] In this embodiment, not only the span dimension of the gap but also the depth dimension of the gap can be used to guide the electric field, which effectively contributes to radiating the RF signal, and thus a small conductive element can provide a sufficient antenna length.

[0020] In other words, the effective length of the edge of the rim along which the electric field is induced by the wire antenna element (thereby causing the rim to act as a radiating element) is effectively increased by introducing a gap in the rim and positioning the wire antenna to at least partially overlap this gap. The edge of the rim thereby acts to increase the effective length of the rim that radiates the radio frequency signal, facilitating placement of the antenna in a smaller volume and proven to be less sensitive to the presence of potential blocking elements. Thus, the effective radiating length of the rim, which is the length of the edge of the rim that radiates the radio frequency signal, is increased.

[0021] The gap may form a gap separating or spacing the two rim portions.

[0022] In some embodiments, the length of the wire radiating element aligned with and extending parallel to the rim edge is between 7.5 and 50 mm, preferably between 7.5 and 45 mm, and more preferably between 7.5 and 32.5 mm. These embodiments provide preferred implementations of the wire radiating element for good RF performance.

[0023] Optionally, the rim includes a second rim portion, the gap is formed as an air gap between the first rim portion and the second rim portion, and the wire radiating element further includes a third wire portion spatially aligned with and extending parallel to a rim edge of the second rim portion, and a length of the rim edge of the first rim portion and the rim edge of the second rim portion plus a contour length of the gap corresponds to a desired wavelength of the radio frequency signal.

[0024] This embodiment provides a symmetrical antenna structure.

[0025] In some examples, the wire radiating element has a dipole antenna arrangement including: a first conducting element including a first wire portion and a first portion of a second wire portion, where radio frequency current in the first conducting element is configured to induce a non-negligible electric field in the first rim portion and the first portion of the gap; and a second conducting element including a third wire portion and a second portion of the second wire portion, where radio frequency current in the second conducting element is configured to induce a non-negligible electric field in the second rim portion and the second portion of the gap, oriented 180 degrees from the first conducting element.

[0026] The dipole antenna configuration provides a materially efficient approach to providing an antenna structure that can be easily configured and appropriately positioned relative to the gap to achieve good radiation efficiency of the overall antenna structure.

[0027] The dipole antenna configuration may exhibit reflection symmetry, with the axis of reflection of the dipole antenna configuration positioned so that it is spatially aligned with the gap and equidistant from the first and second rim portions. This approach spreads the induced electric field in the conductive element evenly across the portions located on either side of the gap, providing a uniform radiation pattern for the emitted radio frequency signal.

[0028] In some examples, the dipole antenna configuration has a pair of feed points at the reflection axis of the dipole antenna configuration, which results in the feed points being located within the gaps in the conductive elements, improving the performance of the antenna structure.

[0029] The present application is not limited to the symmetrical antennas described above, but may also be asymmetrical (e.g., monopole antennas). The wire radiating element may be a monopole antenna having a feed point at one end of the wire radiating element.

[0030] In some examples, the distance between the wire radiating element and the rim edge of the first rim portion is between 0.5 mm and 3 mm. This approach ensures close electrical coupling between the wire radiating element and the first rim portion and gap, improving electrical flow through the first rim portion and through the gap, thereby improving electromagnetic wave radiation by the first rim portion and gap.

[0031] The gap may be rectangular, trapezoidal, or triangular.

[0032] These shapes effectively provide a substantial depth of gap that contributes to the antenna length, and the conductive element can be easily stamped or otherwise fabricated to have these shapes.

[0033] In some instances, for example, when the gap is rectangular, the span of the gap is between 10 mm and 15 mm.

[0034] The vertical height or depth of the gap, which is perpendicular to the span, is 10 mm to 20 mm.

[0035] These dimensions are suitable to accommodate the antenna length of common 2.4 GHz RF antennas such as Wi-Fi, ZigBee, or Bluetooth, etc. Alternatively, these dimensions can be modified to accommodate antenna lengths for cellular frequency bands.

[0036] The antenna structure may further include a substrate, and the wire radiating element may be on the substrate, e.g., coupled to the substrate. The conductive component may be fixed to the substrate such that the first wire portion and the rim edge of the first rim portion of the wire radiating element are spatially aligned with each other and extend parallel to each other. Positioning the wire radiating element on the substrate can provide reliable positioning of the wire radiating element (relative to the conductive component) while still being easy and efficient to manufacture or assemble.

[0037] The substrate may include a housing that contains and holds the conductive component.

[0038] This embodiment definitely provides a compact design for the appliance having a housing.

[0039] The antenna structure may include an RF circuit board housed in a housing and including RF circuitry. The RF circuitry may be configured to generate a radio frequency signal for controlling the radio frequency signal. Because the RF circuit board does not include an antenna, it is relatively small and can fit into the housing. This provides a more compact structure compared to existing antenna structures or devices including such antenna structures.

[0040] The antenna structure may include at least one feed-in element formed on the housing and electrically connected to the wire radiating element, such that the feed-in element(s) provide radio frequency current (e.g., generated by an RF circuit) to the wire radiating element. The feed element can be positioned to overlap a gap in the conductive element, although this is not required because the feed element does not directly induce an electric field in the conductive element.

[0041] The antenna structure may include at least one connector connecting the feeding element and the RF circuit.

[0042] The connectors can be implemented in a variety of ways, including direct coupling via pogo pins or welding, or indirect coupling via capacitive coupling.

[0043] The at least one feeding element may include a transmission line electrically connected to the wire radiating element and adapted for impedance matching. Because the wire radiating element is used to induce an electric field in the gap as well as in the rim portion, its impedance may need to be matched by using a transmission line.

[0044] In some examples, the conductive component is plate-shaped. The housing may be cup-shaped or cylindrical and have a conformal opening at the rim of the conductive component to receive the plate-shaped conductive component; optionally, a wire radiating element may be positioned along the opening of the housing such that the wire radiating element is conformal and aligned with the rim of the conductive element. Preferably, the conductive component is a heat spreader or heat sink. This embodiment recognizes that the conductive component can serve a dual purpose: contributing to the emission / radiation of radio frequency signals and performing the additional function of heat spreading / sinking. Notably, existing heat spreaders / sinks or designs thereof may also be used to radiate radio frequency signals.

[0045] Also proposed is an LED lighting device (e.g., a lamp or bulb) that includes the above-mentioned antenna structure (wherein the conductive component is a heat spreader) and an LED lighting unit that is disposed on the heat spreader and thermally coupled to the heat spreader.

[0046] Also proposed is an electronic device including an antenna structure as described above and a metal casing that at least partially surrounds or encloses the antenna structure.

[0047] The electronic device may be an LED lighting device, such as a lamp or bulb, that further includes an LED lighting unit.

[0048] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. [Brief explanation of the drawings]

[0049] For a better understanding of the present invention, and to show more clearly how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which: [Figure 1] 1 illustrates an antenna structure according to one embodiment. [Figure 2] 1 provides another view of the antenna structure. [Figure 3] 1 shows the induced currents and / or electric fields in the antenna structure. [Figure 4] 10 illustrates additional optional features of the antenna structure. [Figure 5] 1 shows an electronic device including the proposed antenna structure. [Figure 6] The efficiency of the proposed antenna structure is shown. [Figure 7] 1 shows the far-field radiation pattern of the proposed antenna structure. [Figure 8] 1 shows the far-field radiation pattern of the proposed antenna structure. [Figure 9] 1 shows simulated currents in the antenna structure. [Figure 10] 1 shows a first monopole antenna structure. [Figure 11] 2 shows a second monopole antenna structure. [Figure 12] 1 shows the efficiency of the monopole antenna structure. [Figure 13] 1 shows the far-field radiation pattern of a first monopole antenna structure. [Figure 14] 1 shows the far-field radiation pattern of a first monopole antenna structure. [Figure 15]1 shows the far-field radiation pattern of a second monopole antenna structure. [Figure 16] 1 shows the far-field radiation pattern of a second monopole antenna structure. [Figure 17] 1 shows an antenna structure having a ring antenna. [Figure 18] 1 shows simulated currents in an antenna structure with a ring antenna. DETAILED DESCRIPTION OF THE INVENTION

[0050] The present invention will now be described with reference to the drawings.

[0051] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the devices, systems, and methods, are for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the devices, systems, and methods of the present invention will become better understood from the following description, the appended claims, and the accompanying drawings. It should be understood that the drawings are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used to denote the same or similar parts throughout the drawings.

[0052] The present invention provides an antenna structure for radiating radio frequency signals. The antenna structure includes a conductive element having a rim defining a gap. A wire antenna element is positioned to partially overlap the rim and partially overlap the gap. The wire antenna element is configured such that a radio frequency current flowing or induced through the wire antenna element induces an electric field at the overlapping portion of the rim and at the edge of the gap, causing the overlapping portion of the rim and the edge of the gap to radiate a radio frequency signal in response to the radio frequency current.

[0053] The proposed embodiments can be used in any device or product where an antenna structure is desired. However, the advantages of the proposed embodiments are particularly pronounced or well-seen when the antenna structure is enclosed or surrounded by a metal casing, as is relatively common in, for example, lamps or lighting devices. In particular, unlike existing antenna structures, the efficiency of the proposed antenna structure suffers a lower loss of efficiency when enclosed or surrounded by a metal casing compared to existing antenna structures.

[0054] 1 conceptually illustrates an antenna structure 100 according to one embodiment. The antenna structure includes a conductive element 110 and a wire radiating element 120.

[0055] The conductive element 110 is formed of a conductive material, particularly an electrically and / or thermally conductive material such as a metal. Exemplary metals include aluminum, copper, steel, iron, etc. The conductive element 110 may be a heat spreader for an electronic device, such as a lighting device or lamp.

[0056] The conductive component 110 includes a rim 115. The rim is formed of at least a first rim portion 111 and a gap 119 adjacent the first rim portion. In a preferred embodiment, the rim may be formed, for example, of a first rim portion 111 and a second rim portion 112 separated by the gap 119. For example, the gap 119 may be formed as an air gap between the first rim portion 111 and the second rim portion 112. In this manner, the gap 119 may be formed as a slot, slit, or cutout in the rim 115 of the conductive component 110. Alternatively, an electrically insulating material may be present in the gap to "replace" the air. For example, if heat dissipation is highly required, a ceramic material may fill the gap. The ceramic material may conduct and dissipate heat well, but may leave a conductive edge or contour of the gap so that an electric field can be induced by the wire radiating element 120.

[0057] The gap 119 may be formed in any shape, such as rectangular, trapezoidal, or triangular, etc. In the illustrated example, the gap is generally rectangular with slightly rounded corners.

[0058] The wire radiating element 120 is electrically isolated from the conductive component 110. This can be achieved, for example, by separating them by an air gap or a gap filled with an electrically insulating material.

[0059] Wire radiating element 120 includes at least a first wire portion 121 that is spatially aligned with first rim portion 111. Wire radiating element 110 also includes a second wire portion 122 that spans a portion of gap 119. Thus, in the illustrated example, second wire portion 122 is spatially aligned with and spans gap 119.

[0060] In the context of the present disclosure, when a feature of a wire radiating element is spatially aligned with a feature of a conductive element, this indicates that the closest part of the conductive element to the feature of the wire radiating element is that feature of the conductive element.

[0061] The wire radiating element is positioned and / or configured such that, when supplied with radio frequency current, an electric field is induced within the first rim portion and the gap, which electric field causes the first rim portion and the gap to radiate a radio frequency signal in response to the radio frequency current supplied to the wire radiating element.

[0062] In particular, the electric field induces surface currents along the outermost edge of the rim 115, including the first rim portion 111 and the edge of the gap 119. This surface current distribution effectively activates / configures the rim (especially in the region adjacent to the wire radiating element) as a radiator of radio frequency signals. In particular, the boundaries of the rim 115, including the first rim portion 111 and the edge of the gap 119 that are close to the wire radiating element, radiate radio frequency signals.

[0063] Stated further, radio frequency current through the wire radiating element 120 is coupled to the first rim portion 111 of the conductive component 110 and the edge of the gap 119. In particular, a current is induced in the conductive element. The wire radiating element is positioned such that the rim portion of the conductive component and the edge of the gap are stimulated.

[0064] In this manner, the rim 115, including the rim portion 111 and gap 119 of the conductive component 110, contributes to the radiation of the radio frequency signal. This improves the radiation performance of the entire antenna structure beyond what was previously possible using solely a wire radiating element or a slot antenna located on the conductive component. Furthermore, the depth of the gap (i.e., the edges of the gap stretching in the depth direction) is also used to radiate the radio frequency signal. In this manner, a desired antenna length can be obtained with a smaller total span of the gap / perimeter of the rim 115, allowing the conductive element to be small and suitable for small applications.

[0065] A radio frequency signal is an emission or radiation of electromagnetic waves at radio frequencies. The frequency of the emitted electromagnetic waves depends on the effective length of the rim in which the electric field is induced, which in this case is the length of the rim portion plus the contour / edge length of the gap, including twice the depth of the gap and the span width. Other factors may affect the precise frequency of the radio frequency signal emitted by the first rim portion and gap, some of which are described below.

[0066] The conductive elements can serve the dual role of assisting in the radiation of radio frequency signals and performing other conductive functions such as heat spreading or dissipation.

[0067] Another advantage of the proposed approach is that good antenna performance can be achieved while positioning the wire antenna element 120 closely to the conductive element 110. This means that more compact devices (including the proposed antenna structure 100) can be provided or manufactured.

[0068] The shape of the wire antenna element 120 may match or correspond to the shape of the rim 115 of the conductive element 120. Thus, the shape of the wire antenna element may geometrically match the shape of the rim 115 of the conductive element 120. This improves coupling between the wire antenna element and the conductive element, thereby improving the efficiency of the antenna structure.

[0069] In a preferred example, the length of first rim portion 111 plus the contour length of gap 119 corresponds to the desired wavelength of the radio frequency signal. The contour length of gap 119 is the total length of the edges of the gap along which current is induced by wire antenna element 120 in the conductive element. For the illustrated wire radiating element, this includes twice the depth of the gap plus the span width of the gap, since an electric field is induced along all edges of the gap by antenna element 120 when conducting.

[0070] In the illustrated example, the wire radiating element 120 is configured in a dipole antenna configuration.

[0071] The dipole antenna configuration includes a first conductive element 127 formed by first wire portion 121 and first portion 122A of second wire portion 122. In this manner, radio frequency current in the first conductive element induces a non-negligible electric field in first rim portion 111 and the first portion of the gap.

[0072] The dipole antenna configuration also includes a second conductive element formed by third wire portion 123 (spatially aligned with second rim portion 112) and second portion 122B of the second wire portion. In this manner, radio frequency current in the second conductive element induces a non-negligible electric field in the second rim portion and the second portion of the gap.

[0073] The second conductive element 128 is oriented 180 degrees from the first conductive element 127. Thus, the second conductive element 128 is oriented or facing in the opposite direction as the first conductive element 127.

[0074] In some examples, the antenna structure 100 may further include a pair of feeding elements 171, 172. The feeding elements are configured to conduct radio frequency current through the wire radiating element 120. As such, the feeding elements 171, 172 may provide an electrical connection to a radio frequency generator (not shown) for driving the antenna structure.

[0075] In the illustrated example, the feed element is positioned to overlap gap 119 in conductive element 110. The feed element extends from the bottom of gap 119 to the top of the gap, contacting the wire at the top. However, the feed element does not actively induce an electric field in the rim portion or the edge of the gap. In an alternative embodiment, the feed element can be turned 90 degrees and lie in the plane of rim 115.

[0076] The feed elements 171, 172 connect to the dipole antenna configuration 120 at feed points 175, 176. In the illustrated example, the feed points include a first feed point for the first portion 122A of the second wire portion and a second feed point for the second portion 122B of the second wire portion.

[0077] The distance between the feed points 175, 176 changes or modifies the bandwidth of the antenna structure. Thus, by defining or setting the distance between the feed points 175, 176, it is possible to tune the bandwidth of the antenna structure.

[0078] The resonant frequency of the antenna structure is defined at least in part by the length of the wire antenna element. Thus, defining or modifying the length of the wire antenna element can be used to define or modify the resonant frequency of the antenna structure. The resonant frequency of the antenna structure is also defined at least in part by the depth of the gap. This is described in more detail with reference to FIG. 2.

[0079] 2 conceptually illustrates the spatial relationship between wire radiating element 120 and conductive element 110 for a dipole antenna configuration. In particular, it clearly shows how a portion of the wire antenna element (second wire portion 122) is positioned to overlap gap 119 in conductive element 110.

[0080] By forming the wire antenna element in this configuration, the electric field induced in the conductive element 110 is distributed under the first rim portion 111, the two side edges and bottom of the gap 119, and the second rim portion 112.

[0081] FIG. 2 also illustrates how a dipole antenna configuration may exhibit reflection symmetry, where the reflection axis A of the dipole antenna configuration R is positioned so as to be spatially aligned with gap 119 and equidistant from first rim portion 111 and second rim portion 112.

[0082] The feed points 175 and 176 are located along the reflection axis A of the dipole antenna configuration 120. R In other words, the feed points 175, 176 may be positioned closer to the reflection axis A than any other part / portion of the wire radiating element 120. R It may be located in close proximity to

[0083] FIG. 2 also shows the width W of the gap 119. g or span, and the vertical height or depth D of the gap 119 gWidth W g is the distance across the gap, e.g., the distance in the direction away from the first rim portion 111 or between the first and second rim portions. g is the width W g is the gap distance in the direction perpendicular to the

[0084] Thus, the effective radiating length is the sum of the length L1 of the first wire portion 121 and the depth D of the gap. g , gap width W g 2 halves of the gap depth D g , and the length L2 of the third wire portion 123. The effective radiation length is the effective length of the edge of the rim that radiates a radio frequency signal in response to the current flowing through the wire antenna (as a result of the induced electric field at the rim of the conductive element). Mathematically, the effective radiation length L of the illustrated antenna structure is R can be defined as follows:

[0085] TIFF2025530863000002.tif15131

[0086] For improved / maximized efficiency, the radiation length is equal to 1 / 2 the lambda of the (desired) radio frequency signal.

[0087] Gap span or width W g The vertical height or depth D of the gap may be 10 mm to 15 mm. g The gap may be 10 mm to 20 mm. These dimensions make the gap suitable for a portion of the radiation length of the widely used 2.4 GHz radio frequency signal.

[0088] FIG. 3 illustrates the effect of feeding or providing a radio frequency current to a wire radiating element 120 .

[0089] In particular, radio frequency current (shown by the small arrows) flowing through the wire radiating element 120 induces an electric field (shown by the dotted arrows) within at least the first rim portion 111 and the (edges of) the gap 119. As a result, the first rim portion 111 and the (edges of) the gap 119 radiate a radio frequency signal.

[0090] Of course, in the illustrated dipole antenna configuration, radio frequency current flowing through wire radiating element 120 also induces an electric field (shown by the dashed arrows) within at least second rim portion 112 and the edges of gap 119. As a result, second rim portion 112 contributes to the radiation of radio frequency signals.

[0091] 3 also illustrates the shape of the conductive component 110 according to some examples. In particular, the conductive component may be plate-like. In particular, the conductive component may include a planar portion 310 at the bottom of the plate and protruding portions 320 located around the edges of the planar portion 310 as lateral edges of the plate. The protruding portions 320 may define rims of the conductive component. The planar portion 310 may be replaced by a tapering portion (e.g., a conical portion).

[0092] FIG. 4 shows further optional features and configuration details for the antenna structure 100.

[0093] Among other things, the antenna structure 100 may include a substrate 410. The wire radiating element 120 may be positioned on the substrate 410. The conductive component 110 is bonded or fixed onto the substrate such that the first wire portion and the first rim portion of the wire radiating element are spatially aligned.

[0094] In the illustrated example, the base 410 is formed as a housing. The housing accommodates and holds the conductive component 110. In some examples, the housing is cup-shaped or cylindrical, for example, formed as a cylinder or with a tapered structure. The housing may be formed of any suitable material, for example, a plastic material. Preferably, the housing is formed of an electrically insulating material, such as a plastic, ceramic, or dielectric material.

[0095] The housing may include an opening 415 that conforms to or is sized to accommodate the rim of the conductive component, thereby receiving the conductive component. The wire radiating element may be positioned along the opening in the housing such that the wire radiating element is therefore conformal, thereby aligning the wire radiating element with the rim of the conductive element.

[0096] The wire radiating element 120 can be formed on the substrate using a metal printing process, or by overmolding or other manners of mounting the wire radiating element in / on the substrate 410. These techniques provide an antenna structure that can be easily manufactured.

[0097] For improved energy coupling between the wire radiating element and the conductive element, the coupling distance (i.e., the distance between the wire radiating element and the conductive element) should be relatively small, e.g., ≦5 mm or ≦3 mm. However, to maintain clearance, e.g., to prevent / avoid arcing, the distance is preferably 0.1 mm or more, e.g., 0.2 mm or more. In some preferred examples, the distance between the wire radiating element and the first rim portion is 0.5 mm to 3 mm.

[0098] Other characteristics that affect the impedance and resonant frequency of the antenna structure include the size of the gap and the length of the wire radiating element (particularly the length of each conductive element in the case of a dipole antenna configuration).

[0099] 5 shows a luminaire 500 or lamp with a metal casing 510 of the luminaire, where the lamp with the antenna structure is mounted in the luminaire and the metal casing 510 encloses the lamp / antenna structure. The metal casing 500 includes an opening to expose the antenna structure.

[0100] For completeness of disclosure, Figure 5 shows a metal casing 510 surrounding the antenna structure 100. The metal casing 510 can effectively represent the housing or outer casing of a lamp / lighting fixture or other electronic device.

[0101] Figure 6 is a graph derived from experimental data on radiation efficiency showing the effect of the proposed antenna structure on a lighting fixture such as that shown in Figure 5. In the graph, the x-axis is the frequency f (GHz) of the radiated signal emitted by the antenna structure, and the y-axis is efficiency measured on a scale of 0 to 1 (1 represents perfect radiation with no signal blocking, and 0 represents all signals are blocked and cannot be detected externally).

[0102] The first waveform 610 shows the efficiency of a lamp with the proposed antenna structure, such as that shown in Figures 1-4. The second waveform 620 shows the efficiency of a conventional lamp in which a conventional or standard PIFA antenna structure is encased in the lamp housing. In both scenarios, the lamp is encased in the luminaire structure shown in Figure 5, the antenna structure is surrounded by or bounded within a metal casing, and the antenna structure is positioned in the same relative position within the metal casing. Also, note that without the metal casing, the efficiency of both of these antenna structures is similar, approximately 0.81 (at 2.5 GHz).

[0103] The difference between the first waveform 610 and the second waveform 620 clearly demonstrates the superior performance of the proposed antenna structure. In particular, the efficiency of the proposed antenna structure is much greater than that of conventional antenna structures, and the efficiency loss due to being placed inside a metal casing is significantly reduced (<0.1).

[0104] Figure 7 shows the far-field radiation pattern of an antenna structure (i.e., without a metal casing) as depicted in Figure 4. Figure 8 shows the far-field radiation pattern of an electronic device as depicted in Figure 5.

[0105] In both radiation patterns, the value of Phi is fixed at 0 and the frequency of the radiated radio frequency signal is 2.4 GHz. The radiated power (measured in dBi) is provided for different values ​​of Theta.

[0106] 9 is a simulation showing the surface currents in the conductive element 110 when an electromagnetic current is applied to the wire antenna element 120. The lighter colored areas indicate greater surface currents than the darker colored areas.

[0107] 9 clearly shows how the surface current distribution is concentrated or gathered in the first rim portion 111, the second rim portion 112, and within the gap 119 (i.e., the portions of the conductive element at the edges of the gap or near the gap 119). This shows how these areas are activated as radiators of electromagnetic waves (i.e., radio frequency signals).

[0108] In the examples disclosed above, the wire radiating elements are configured as a dipole antenna configuration, however, this configuration is not required and the wire antenna elements may instead be configured as any other suitable wire antenna element, such as a monopole antenna or a ring antenna.

[0109] 10 and 11 show alternative embodiments in which the wire antenna elements 1020, 1120 are formed as monopole antennas. In either embodiment, the wire radiating antennas 1020, 1120 are formed as asymmetric antennas with a single feed point at one end of the wire radiating antenna.

[0110] Other features of the antenna structure may be the same as or equivalent to the previously described embodiments.

[0111] 10 thus provides an example representation of the spatial relationship between the conductive element 1010 and the wire radiating element 1020 of the first monopole / asymmetric antenna structure 1000. The conductive element 1010 again includes a first rim portion 1011 and a gap 1019.

[0112] In the illustrated example, wire radiating element 1020 is formed as a monopole antenna having a first wire portion 1021 spatially aligned with first limb portion 1011 and a second wire portion 1022 that spans a portion of gap 1019, where the portion is only a portion of gap 1019.

[0113] The second wire portion 1022 is connected to a single feed element 1070 configured to conduct a radio frequency signal to the wire antenna element 1020 at a feed point 1075. The feed element is thus positioned to overlap or spatially align with the gap 1019.

[0114] The conductive element 1010 may include a second rim portion 1012 as shown (where a gap exists between the first and second rim portions). However, this is not required and may alternatively be omitted. For example, the second rim portion may be replaced with a non-conductive element.

[0115] For the antenna structure 1000 shown in FIG. 11, the effective radiation length L R can be approximated using the following formula:

[0116] TIFF2025530863000003.tif13128 where L 1021 is the length of the first wire section, and L 1022 is the length of the second wire section, and D g is the gap depth.

[0117] 11 provides an example representation of the spatial relationship between a conductive element 1110 and a wire radiating element 1120 of a second monopole / asymmetric antenna structure 1100. The conductive element 1110 includes a first rim portion 1111, a second rim portion 1112, and a gap 1119 therebetween.

[0118] The wire radiating element 1120 is again formed as a monopole antenna having a first wire portion 1121 spatially aligned with the first rim portion 1111, a second wire portion 1122 spanning a portion of the gap 1119, and a third wire portion 1123 spatially aligned with the second rim portion 1123.

[0119] The third wire portion 1123 is connected to a single feed element 1170 configured to conduct a radio frequency signal to the wire antenna element 1120 at a feed point 1175. As such, the feed element 1175 is positioned to overlap or spatially align with the second rim portion 1123.

[0120] For the antenna structure 1100 shown in FIG. 11, the effective radiation length R L can be defined similarly to equation (1), where L1 is instead the length of the first limb portion 111 that the wire radiating element 1120 overlaps (i.e., the length of the first wire portion), and L2 is instead the length of the second limb portion that the wire radiating element overlaps (i.e., the length of the second wire portion).

[0121] FIG. 12 is a graph, derived from experimental data on radiation efficiency, showing the effect of the proposed antenna structure in a luminaire such as that shown in FIGS.

[0122] In the graph, the x-axis is the frequency f (GHz) of the radiated signal emitted by the antenna structure, and the y-axis is the efficiency Ef measured on a scale of 0 to 1 (1 represents perfect radiation with no signal blocking, and 0 represents all signals being blocked and unable to be detected externally).

[0123] A third waveform 1210 shows the efficiency of a lamp having an antenna structure as shown in Figure 10. A fourth waveform 1220 shows the efficiency of a lamp having an antenna structure as shown in Figure 10.

[0124] Figure 12 shows how the monopole antenna shown by Figure 10 can radiate 47% of the energy from the feed point (i.e., have an efficiency of 0.47) at 2.45 GHz, which is significantly greater than that of a PIFA antenna (as shown in Figure 6). Figure 12 also shows how the monopole antenna shown by Figure 11 can radiate approximately 50% of the energy supplied to the feed point (i.e., have an efficiency of 0.5) at 2.45 GHz.

[0125] Such high efficiency ensures a stable emission of energy and a stable connection between devices that communicate using such energy and other devices that receive such energy.

[0126] 13 and 14 show the far-field radiation patterns of the first monopole antenna structure as depicted in FIG. 10 (ie, without the metal casing) for different values ​​of Phi.

[0127] 15 and 16 show the far-field radiation patterns of the second monopole antenna structure as depicted in FIG. 11 (ie, without the metal casing) for different values ​​of Phi.

[0128] The radiation patterns of the monopole antenna structures of the two embodiments show that the main lobe magnitude of both antennas is greater than 4 dBi. Thus, both antenna configurations (and antenna positioning) can act as directional antennas suitable for use with metal housings.

[0129] Due to the symmetrical structure of the dipole antenna, the efficiency of the dipole antenna structure is slightly higher than that of the asymmetrical monopole antenna (as shown in Figure 6). However, the monopole antenna can be adapted to take advantage of reduced material costs and / or compact structure. According to the radiation patterns of the two types of antennas, the main lobe magnitude of both antennas is more than 4 dBi, and both are directional antennas that can be used with metal cans / housings.

[0130] It has been recognized that due to the symmetrical structure of a dipole antenna, its efficiency at 2.45 GHz is higher than that of an asymmetrical monopole antenna (as shown in Figure 5). However, monopole antennas may be adapted to reap the benefits of reduced material requirements, cost, and / or space occupied by the antenna.

[0131] As previously mentioned, yet another example of a suitable wire radiating element is a ring antenna.

[0132] FIG. 17 shows an example of an antenna structure 1700 in which the wire radiating element 1720 is a ring antenna.

[0133] Here, ring antenna 1720 is configured or sized to follow the (entire) edge or boundary of rim 1715 of conductive element 1710, such that when radio frequency current is supplied to ring antenna 1720, the entire edge / boundary of the conductive element effectively contributes to the radiation of the radio frequency signal. Ring antenna 1720 may be coupled to one or more feeding elements 1770 located in gaps 1719 defined in the conductive element.

[0134] In particular, if the ring antenna is shaped and sized to follow the edge or border of the rim, the followed edge of the conductive element becomes the primary radiator of the radio frequency signals.

[0135] 18 is a simulation showing the surface currents in the conductive element 1210 when an electromagnetic current is applied to a wire antenna element 1220 in the form of a ring antenna. The lighter areas show greater surface currents than the darker areas.

[0136] 18 clearly shows how the surface current distribution is distributed across the rim edge or boundary of the conductive element 1210. Thus, the top edge of the conductive element becomes a radiator, or primary radiator, of the electromagnetic waves representing the radio frequency signals.

[0137] However, this figure also shows how the edges of the gap also contribute to the radiation of electromagnetic waves, and therefore to the radio frequency signal. Thus, the effective radiation length of the entire antenna structure is increased without increasing material costs.

[0138] Examples of gap dimensions are described above with reference to the first-mentioned embodiment, but are equally applicable to other embodiments of the present disclosure.

[0139] Other optional features of the antenna structure are described below.

[0140] In some examples where the antenna structure includes a housing, the antenna structure includes an RF (radio frequency) circuit board housed in the housing and including RF circuitry. The antenna structure may further include a connector connecting a feed element of the antenna structure to the RF circuitry. The RF circuitry may be configured to control the flow of radio frequency current to and from the wire antenna (via the connector(s) and the feed element).

[0141] The feeding element of the antenna structure may include a transmission line, or may be such a transmission line, which is electrically connected to the wire radiation element and adapted to perform impedance matching.

[0142] Also proposed is an electronic device including any of the above-described antenna structures and a metal casing that houses the antenna structure. The proposed antenna structure provides a reduction in sensitivity to the metal casing and is thus particularly advantageous in such use case scenarios. The metal casing may have an opening on one side. The antenna structure may be positioned close to this opening in order to improve radiation efficiency.

[0143] Preferably, the distance between the metal casing and the conductive element of the antenna structure is 5 mm or more, for example 10 mm or more. This further improves the efficiency of the antenna structure.

[0144] Preferably, the distance (D1) between the wire antenna element and the conductive element is much smaller than the distance (D2) between the wire antenna element and the metal casing. Thus, D1 < D2. For example, 5·D1 < D2, for example, 10·D1 < D2.

[0145] Also provided may be an LED lighting device including the antenna structure and an LED lighting unit disposed on the conductive element and thermally coupled to the conductive element. In particular, the conductive element may be a heat spreader for the LED lighting unit. The LED lighting unit may include one or more LEDs configured to emit light. Suitable configurations for the LED lighting unit are well established in the art.

[0146] The proposed antenna structure can be configured such that the radiation pattern beam output by the antenna structure mainly faces the light direction (since the heat spreader for the LED lighting unit is positioned to be aligned with the light direction), and is thus particularly advantageous for use in such LED lighting devices.

[0147] When the LED lighting device includes a metal casing, the proposed antenna structure is even more advantageous because the heat spreader is naturally positioned towards the opening in the metal casing (e.g., because that is the location from which the light is output) so that the radiation pattern beam emitted by the antenna structure is directed outward from the opening in the metal casing.

[0148] TIFF2025530863000004.tif91125

[0149] Table 1 shows the advantages of using the proposed antenna structure when it is surrounded or enclosed by a metal casing. In particular, the effect of the casing on the total radiated power (TRP) is shown for three different types of antenna structures. The PIFA antenna structure is an existing antenna structure (e.g., not utilizing the proposed gap-based system). The dipole and ring antenna approaches have already been mentioned.

[0150] Table 1 clearly shows how the loss of radiated power is significantly reduced using the proposed approach when a metal casing is introduced. Table 1 also clearly shows the significant impact that the metal casing has on the efficiency of the existing antenna structure.

[0151] The present disclosure recognizes that providing gaps in the rim of a conductive element (and appropriately positioning a wire antenna element) can be used to repurpose the conductive element as a radiator of radio frequency signals. The design of the gaps in the conductive element can affect the frequency of the radio frequency signal.

[0152] In particular, the gap should be designed so that the radiation frequency of the conductive element is the same as the working frequency of the wire antenna element.

[0153] The most convenient way to design or configure the gap would be to use characteristic mode analysis techniques to characterize the conductive element, which can be used, for example, to find the modes of the conductive element at the desired frequency.

[0154] Variations to the disclosed embodiments can be understood by those skilled in the art, from a study of the drawings, the disclosure, and the appended claims, and can be implemented in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0155] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0156] It should be noted that when the term "adapted to" is used in the claims or the specification, it is intended to be equivalent to the term "configured to." It should be noted that when the term "arrangement" is used in the claims or the specification, it is intended to be equivalent to the term "system," and vice versa.

[0157] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A conductive component having a rim including a first rim portion having a first rim edge and a gap adjacent to the first rim portion, A wire radiating element electrically insulated from the conductive component, comprising a first wire portion spatially aligned with and parallel to the first rim edge of the first rim portion, and a second wire portion extending over the gapped portion, An antenna structure including, The first rim edge is electromagnetically exposed when the antenna structure is assembled and ready for operation, and the wire radiating element is configured to induce an electric field within the first rim portion and the edge of the gap when a radio frequency current is supplied, causing the electromagnetically exposed first rim edge of the first rim portion and the edge of the gap to radiate a radio frequency signal corresponding to the radio frequency current supplied to the wire radiating element. When forming a monopole antenna, the length of the wire radiation element aligned with and extending parallel to the rim edge plus the contour length of the gap is the effective radiation length. An antenna structure in which, when forming a dipole antenna, the rim further includes a second rim portion having a second rim edge, the gap is formed as an air gap between the first rim portion and the second rim portion, the wire radiating element further includes a third wire portion that is spatially aligned with and extends parallel to the second rim edge, and the effective radiating length is the length of the rim edges of the first and second rim portions plus the contour length of the gap.

2. The antenna structure according to claim 1, wherein, when forming a dipole antenna, the length of the wire radiating element aligned with and extending parallel to the rim edge is 7.5 to 50 mm, preferably 7.5 to 45 mm, and more preferably 7.5 to 32.5 mm.

3. The antenna structure according to claim 2, wherein the contour length of the gap includes twice the depth of the gap plus the span width of the gap.

4. If the wire radiation element is a dipole antenna, the dipole antenna is A first conducting element comprising the first wire portion and the first portion of the second wire portion, wherein the radio frequency current in the first conducting element is configured to induce a non-negligible electric field in the first rim portion and the first portion of the gap, A second conducting element, which includes the third wire portion and the second portion of the second wire portion, is oriented 180° from the first conducting element, and is configured such that a radio frequency current in the second conducting element induces a non-negligible electric field in the second rim portion and the second portion of the gap, The antenna structure according to claim 3, including the following:

5. The dipole antenna configuration exhibits reflection symmetry, The reflecting axis of the dipole antenna configuration is positioned to be spatially aligned with the gap and equidistant from the first rim portion and the second rim portion. The antenna structure according to claim 4, wherein the dipole antenna configuration has a pair of feed points on the reflection axis of the dipole antenna configuration.

6. The antenna structure according to claim 1, wherein, in the case of a monopole antenna, the wire radiating element has a feed point at one end of the wire radiating element.

7. The antenna structure according to claim 1, wherein the distance between the wire radiation element and the rim edge of the first rim portion is 0.5 mm to 3 mm.

8. The gap is rectangular, trapezoidal, or triangular in shape, and if the gap is rectangular, the span of the gap is 10 mm to 15 mm. The antenna structure according to claim 1, wherein the vertical height or depth of the gap, which is perpendicular to the span, is 10 mm to 20 mm.

9. The antenna structure further includes a base, The wire radiation element is located on the substrate, The antenna structure according to claim 1, wherein the conductive component is fixed to the base such that the rim edges of the first wire portion and the first rim portion of the wire radiation element are spatially aligned with each other and extend parallel to each other.

10. The antenna structure according to claim 9, wherein the substrate includes a housing for accommodating and holding the conductive component.

11. The antenna structure further, The housing contains an RF circuit board including an RF circuit, A power supply element formed on the housing and electrically connected to the wire radiation element, A connector connecting the power supply element and the RF circuit, The antenna structure according to claim 10, including the following:

12. The antenna structure according to claim 11, wherein the power supply element includes a transmission line that is electrically connected to the wire radiating element and adapted to perform impedance matching.

13. The conductive component is plate-shaped, The housing is cup-shaped or cylindrical and has a conformal opening in the rim of the conductive component for receiving the plate-shaped conductive component. The antenna structure according to claim 10, wherein the wire radiating element is positioned along the opening of the housing such that the wire radiating element conforms to align with the rim of the conductive element.

14. The antenna structure according to claim 1, wherein the conductive component is a heat spreader.

15. The antenna structure according to claim 14, An LED lighting unit is placed on the heat spreader and is thermally coupled to the heat spreader. LED lighting devices, including...

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