Antenna structure

Abstract

An antenna structure for radiating radio frequency signals. The antenna structure includes a conductive element having a bezel with a bezel edge and a gap. The wire antenna element is positioned so as to partially overlap with the bezel and so as to partially overlap with the gap by extending in parallel with the bezel edge. In a state in which the antenna structure is assembled and ready for operation, the bezel edge is electromagnetically exposed, and the wire antenna element is configured such that a radio frequency current induced or flowing through the wire antenna element induces an electric field in an overlapping portion of the bezel and an edge of the gap, thus, the overlapped electromagnetically exposed bezel edge of the portion of the bezel and the edge of the gap radiate the radio frequency signal in response to a radio frequency current.

Description

Technical Field

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

[0002] Antenna structures are widely used in the field of radio frequency communications to radiate and receive radio frequency signals. In particular, antenna structures are often used to allow a transceiver to communicate with other devices having the antenna structure.

[0003] There is a growing interest in developing compact antenna structures, such as those that can fit within a housing or casing of a luminaire. Significant challenges exist in such use case scenarios, as the presence of the housing or casing and any conductive elements inherent to such devices (e.g., heat sinks or heat spreaders) can significantly impact the efficiency of the antenna structure.

[0004] Standard radio frequency (RF) boards with a planar inverted F antenna (PIFA) printed on the board have been 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 will interfere with the RF performance of the antenna.

[0005] It is also known to cut a slot on the heat sink of the lamp, the slot having a length corresponding to half or a quarter λ of a desired or target RF signal, and place an RF radiator in the heat sink and near the slot to induce an electric field on the slot so that the slot emits RF radiation to the outside. λ represents the wavelength of the desired RF signal. This requires a large heat sink to form the slot, and the slot may negatively affect the heat dissipation of the heat sink.

[0006] Therefore, there is a need for a design of an antenna structure that can be efficiently implemented within a limited space and surrounded by those obstructing elements present in the lamp.

[0007] US20160183353A1 discloses a light bulb with an open antenna.

[0008] US20160072176A1 discloses a light bulb having a slotted antenna. Summary of the invention

[0009] The invention is defined by the claims.

[0010] The proposed invention overcomes the above mentioned problems by using a conductive element to supplement a wire antenna element to improve the radiation of the radio frequency signal. In particular, it has been recognized that positioning the wire antenna element close to the border of the conductive element and configuring the border to provide a slot or gap so that the wire antenna also at least partially overlaps the slot or gap causes the border of the conductive element (including the gap) to radiate the radio frequency signal. In particular, if the antenna structure is also surrounded by a housing / casing, the efficiency of such an antenna structure is much higher than that of a pure wire antenna element alone.

[0011] The gap is formed in the edge of the frame to effectively be a cutout or recess from the edge of the frame, for example. The gap effectively expands the outline length of the frame on which the wire antenna induces an electric field (e.g., the total length or size of the edge) so that the conductive element can use two dimensions to provide the necessary length, for example, the necessary length corresponds to half a lambda or a quarter lambda. Therefore, the proposed invention can be suitable for small size applications or devices such as lamps.

[0012] For example, the conductive element may be an existing conductive element inherent to the electronic device - such as a heat sink or heat spreader of the electronic device. This allows the existing element or feature to be repurposed to perform an auxiliary function, thereby improving the efficiency of the antenna structure, without significantly affecting the existing function of the electronic device incorporating the antenna structure and / or without requiring additional components (and therefore without requiring additional material costs). Furthermore, since the gap only forms a portion of the length, its depth can be reduced relative to a simple slotted antenna. Therefore, the proposed embodiments do not significantly affect the heat dissipation capabilities of the heat sink.

[0013] According to an example according to one aspect of the present invention, an antenna structure is provided, comprising: a conductive component having a frame, the frame comprising a first frame portion having a frame edge and a gap adjacent to the first frame portion; and a wire radiating element electrically isolated from the conductive component, the wire radiating element comprising: a first wire portion, the first wire portion being spatially aligned with the frame edge of the first frame portion and extending parallel to the frame edge of the first frame portion; and a second wire portion, which spans a portion of the gap. In a state where the antenna structure is assembled and ready for operation, the frame edge is electromagnetically exposed, and the wire radiating element is configured to induce an electric field in the edge of the first frame portion and the gap when fed with an RF current, thereby causing the electromagnetically exposed frame edge of the first frame portion and the edge of the gap to radiate an RF signal in response to the RF current fed into the wire radiating element.

[0014] In the proposed method, the gap on the conductive element is designed so that the portion of the conductive element near the gap (including at least the first frame portion) becomes the main radiator of the antenna. This serves to decouple the radiating position away from the wire antenna element, thereby separating the radiating position from the shell or housing of the antenna structure.

[0015] The electric field induced in the first frame portion and the gap effectively induces current across the surface of the first frame portion and the boundary of the conductive element at the gap. The induced surface current causes these elements to radiate energy in the form of electromagnetic waves (ie, radio frequency signals).

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

[0017] In some instances, the length of the wire radiating element aligned with and extending parallel to the edge of the frame plus the profile length of the gap corresponds to the expected wavelength of the RF signal, and preferably, the length of the wire radiating element aligned with and extending parallel to the edge of the frame plus the profile length of the gap is equal to half the expected wavelength of the RF signal.

[0018] The profile length of the gap is the total length along the sides of the gap that also induce an electric field from the antenna, thereby contributing to the generation or radiation of radio frequency signals by the portion of the frame.

[0019] In this embodiment, not only the span dimension of the gap but also the depth dimension of the gap can be utilized to induce an electric field and effectively contribute to transmitting RF signals, so a small conductive element can provide sufficient antenna length.

[0020] In other words, by introducing a gap or cutout in the bezel and positioning the wire antenna to at least partially overlap the gap, the effective length of the edge of the bezel in which the electric field is induced by the wire antenna element (causing the bezel to act as a radiating element) is effectively increased. The edge of the bezel thus serves to increase the effective length of the radiated RF signal of the bezel to help provide the antenna in a smaller volume and which has been shown to be less sensitive to the presence of any potential blocking elements. Thus, the effective radiating length of the bezel (i.e., the length of each edge of the bezel that radiates the RF signal) is increased.

[0021] The gap may form a gap, crack or space between the two frame portions.

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

[0023] Optionally, the frame includes a second frame portion, and the gap is formed as an air gap between the first frame portion and the second frame portion; the wire radiation element also includes a third wire portion, which is spatially aligned with the frame edge of the second frame portion and extends parallel to the frame edge of the second frame portion; and the length of the frame edges of the first frame portion and the second frame portion plus the contour length of the gap corresponds to the expected wavelength of the radio frequency signal.

[0024] This embodiment provides a symmetrical antenna structure.

[0025] In some examples, the wire radiating element includes a dipole antenna arrangement, which includes: a first conductive element, the first conductive element includes the first wire portion and a first portion of the second wire portion, and the first conductive element is configured such that the radio frequency current in the first conductive element induces a non-negligible electric field in the first frame portion and the first portion of the gap; and a second conductive element, the second conductive element is oriented 180° from the first conductive element and includes a third wire portion and a second portion of the second wire portion, and the second conductive element is configured such that the radio frequency current in the second conductive element induces a non-negligible electric field in the second frame portion and the second portion of the gap.

[0026] The dipole antenna arrangement provides a substantially efficient method to provide an antenna structure that can be easily configured and properly positioned relative to the gap to achieve good radiation efficiency of the overall antenna structure.

[0027] The dipole antenna arrangement can have reflection symmetry, wherein a reflection axis of the dipole antenna arrangement is positioned to be spatially aligned with the gap and equidistant from the first frame portion and the second frame portion. The method evenly distributes the induced electric field in the conductive element across portions located on both sides of the gap, which provides a uniform radiation pattern for the transmitted radio frequency signal.

[0028] In some examples, the dipole antenna arrangement includes a pair of feed points at a reflection axis of the dipole antenna arrangement. This results in the feed points being located within the gaps of the conductive elements, resulting in improved performance of the antenna structure.

[0029] The present application is not limited to the symmetrical antennas described above, but may also be asymmetrical (eg, a monopole antenna).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 frame edge of the first frame portion is between 0.5 mm and 3 mm. The method ensures close electrical coupling between the wire radiating element and the first frame portion and the gap to improve the flow of electricity through the first frame portion and the gap, thereby improving the radiation of electromagnetic waves through the first frame portion and the gap.

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

[0032] These shapes effectively provide the gap with sufficient depth to contribute to the antenna length. Furthermore, the conductive element can be easily processed (eg stamped) to have the shape.

[0033] In some examples, such as when the gap is rectangular in shape, the gap spans between 10 mm and 15 mm.

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

[0035] These dimensions are suitable for providing the antenna length of popular 2.4 GHz RF antennas such as WiFi, ZigBee or Bluetooth. Alternatively, these dimensions may be changed to correspond to the antenna length of a cellular band.

[0036] The antenna structure may further include a substrate, wherein the wire radiating element is on the substrate, for example, coupled to the substrate. The conductive component may be fixed to the substrate so that the first wire portion and the frame edges of the first frame 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 (relative to the conductive element) for the wire radiating element while maintaining ease and effectiveness of manufacturing or assembly.

[0037] The substrate may include a housing that houses and holds the conductive components.

[0038] This embodiment provides a compact design for the appliance with a defined housing.

[0039] The antenna structure may include an RF circuit board that is housed in the housing and includes an RF circuit. The RF circuit may be configured to generate a radio frequency signal for controlling the radio frequency signal. Since the RF circuit board does not include an antenna, it may be relatively small and assembled 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 element formed on the housing and electrically connected to the wire radiating element. Thus, the feed element provides a radio frequency current (e.g., generated by an RF circuit) to the wire radiating element. The feed elements may be arranged to overlap with a gap in the conductive element, but this is not required because the feed element does not directly induce an electric field on the conductive element.

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

[0042] The connector can be implemented in different ways, such as direct coupling through pogo pins and soldering, and indirect coupling through capacitive coupling.

[0043] The at least one feeding element may include a transmission line electrically connected to the wire radiating element, adapted to perform impedance matching. Because the wire radiating element is used to induce an electric field on a gap other than the frame 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 include an opening conformal to the frame of the conductive component for receiving the plate-shaped conductive component; and optionally, the wire radiating element is positioned along the opening of the housing so that the wire radiating element is conformal so as to be aligned with the frame of the conductive element. Preferably, the conductive element is a heat sink or a heat transfer device. This embodiment recognizes that the conductive component may perform a dual purpose to facilitate the transmission / radiation of RF signals and to facilitate performing another function of heat dissipation / heat transfer. In particular, existing heat sinks / heat transfer devices or designs thereof may be used to perform radiation of RF signals.

[0045] Also proposed is an LED lighting device (eg, a lamp or a bulb) comprising the previously described antenna structure (wherein the conductive component is a heat sink); and an LED lighting unit placed on and thermally coupled to the heat sink.

[0046] An electronic device is also proposed, comprising the previously described antenna structure and a metal housing at least partially enclosing or surrounding the antenna structure.

[0047] The electronic device may be an LED lighting apparatus (eg, a lamp or a bulb) further comprising an LED lighting unit.

[0048] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] For a better understanding of the invention, and in order 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:

[0050] Figure 1 An antenna structure according to an embodiment is shown;

[0051] Figure 2 Another view of the antenna structure is provided;

[0052] Figure 3 showing induced currents and / or electric fields in an antenna structure;

[0053] Figure 4 Additional optional features of the antenna structure are shown;

[0054] Figure 5 An electronic device including the proposed antenna structure is shown;

[0055] Figure 6 The efficiency of the proposed antenna structure is shown;

[0056] Figure 7 and Figure 8 The far-field radiation pattern of the proposed antenna structure is shown;

[0057] Fig. 9 shows simulated currents in the antenna structure;

[0058] Fig.10 A first monopole antenna structure is shown;

[0059] Fig.11 A second monopole antenna structure is shown;

[0060] Fig.12 The efficiency of the monopole antenna structure is shown;

[0061] Fig.13 and Fig.14 The far-field radiation pattern of a first monopole antenna structure is shown;

[0062] Fig.15 and Fig.16 The far-field radiation pattern for a second monopole antenna structure is shown;

[0063] Fig.17 An antenna structure having a loop antenna is shown; and

[0064] Fig.18 The simulated current flow in an antenna structure with a loop antenna is shown. DETAILED DESCRIPTION

[0065] The present invention will be described with reference to the accompanying drawings.

[0066] It should be understood that the detailed description and specific examples, although representing exemplary embodiments of the device, system and method, are for illustrative purposes only and are not intended to limit the scope of the invention. These and other features, aspects and advantages of the device, system and method of the present invention will be better understood from the following description, the appended claims and the accompanying drawings. It should be understood that the drawings are only schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to represent the same or similar parts.

[0067] The present invention provides an antenna structure for radiating radio frequency signals. The antenna structure includes a conductive element having a frame defining a gap. A wire antenna element is positioned to partially overlap the frame and partially overlap the gap. The wire antenna element is configured so that a radio frequency current induced by or flowing through the wire antenna element induces an electric field in an overlapping portion of the frame and the edge of the gap, so that the overlapping portion of the frame and the edge of the gap radiates the radio frequency signal in response to the radio frequency current.

[0068] The proposed embodiments may be used in any device or product where such an antenna structure is desired. However, the advantages of the proposed embodiments are particularly significant or prevalent when the antenna structure is surrounded or enclosed by a metal housing (e.g., quite common in lamps or lighting devices). In particular, unlike existing antenna structures, the efficiency of the proposed antenna structure has reduced efficiency losses when surrounded or enclosed by a metal housing compared to existing antenna structures.

[0069] Figure 1 An antenna structure 100 according to an embodiment is conceptually shown. The antenna structure comprises a conductive element 110 and a wire radiating element 120.

[0070] The conductive element 110 is formed of a conductive material, in particular a thermally and / or electrically conductive material such as a metal. Exemplary metals include aluminum, copper, steel, iron, etc. The conductive element 110 may be a heat sink for an electronic device such as a lighting device or a lamp.

[0071] The conductive component 110 includes a frame 115. The frame is formed by at least a first frame portion 111 and a gap 119 adjacent to the first frame portion. In a preferred embodiment, the frame can be formed, for example, by a first frame portion 111 and a second frame portion 112 separated by the gap 119. For example, the gap 119 can be formed as an air gap between the first frame portion 111 and the second frame portion 112. In this way, the gap 119 can be formed as a groove, a gap or a cutout in the frame 115 of the conductive component 110. Alternatively, an electrically insulating material can be present in the gap to "replace" the air. For example, if heat dissipation is strongly required, a ceramic material can fill the gap, which can conduct heat and dissipate heat well, but still induce an electric field in the conductive edge or contour of the gap through the wire radiation element 120.

[0072] The gap 119 may be formed in any shape, such as a rectangular, trapezoidal or triangular shape. In the example shown, the gap is generally rectangular in shape with some degree of rounded corners.

[0073] The wire radiating element 120 is electrically insulated from the conducting member 110. This may be achieved, for example, by separating them with an air gap or by the gap being filled with an electrically insulating material.

[0074] The wire radiating element 120 includes at least a first wire portion 121 spatially aligned with the first frame portion 111. The wire radiating element 110 also includes a second wire portion 122 spanning a portion of the gap 119. Thus, in the example shown, the second wire portion 122 is spatially aligned with the gap 119 and spans the gap 119.

[0075] In the context of the present disclosure, if a feature of the wire radiating element is spatially aligned with a feature of the conductive element, this means that the nearest part of the conductive element to the feature of the wire radiating element is said feature of the conductive element.

[0076] The wire radiating element is positioned and / or configured to induce an electric field in the first frame portion and the gap when fed with an RF current. The electric field causes the first frame portion and the gap to radiate an RF signal in response to the RF current fed in the wire radiating element.

[0077] More specifically, the electric field causes surface currents to be induced along the outermost edges of the frame 115 (including the first frame portion 111 and the edges of the gap 119). This surface current distribution effectively activates / configures the frame as a radiator of RF signals (particularly in the area adjacent to the wire radiating element). More specifically, the boundaries of the frame 115 including the first frame portion 111 and the edges of the gap 119 near the wire radiating element will radiate RF signals.

[0078] In other words, the RF current passing through the wire radiating element 120 is coupled to the first frame portion 111 and the edge of the gap 119 of the conductive member 110. Specifically, a current is induced on the conductive element. The positioning of the wire radiating element causes the edge of the gap and the frame portion of the conductive member to be excited.

[0079] Thus, the gap 119 including the conductive member 110 and the frame 115 of the frame portion 111 contribute to the radiation of the RF signal. This enhances the radiation performance of the entire antenna structure, beyond the radiation performance that may have previously been achieved using only wire radiating elements alone or only slotted antennas located on the conductive member alone. Moreover, the depth of the gap (i.e., the edges of the gap extending in the depth direction) is also used to transmit the RF signal. Therefore, the desired antenna length can be obtained with a smaller overall span of the gap / perimeter of the frame 115, making the conductive element smaller and suitable for small applications.

[0080] The radio frequency signal is the emission or radiation of electromagnetic waves at radio frequencies. The frequency of the emitted electromagnetic waves depends on the effective length of the frame in which the electric field has been induced, which in this case is the length of the frame portion plus the outline / edge length of the gap, which includes twice the depth plus the span width of the gap. Other factors may affect the precise frequency of the radio frequency signal emitted by the first frame portion and the gap, some of which are described later.

[0081] Conductive elements may do double duty to facilitate radiation of radio frequency signals and to perform other conductive functions such as heat transfer or dissipation.

[0082] Another advantage of the proposed approach is that good antenna performance can be achieved while positioning the wire antenna element 120 proximately to the conductive element 110. This means that a more compact device (including the proposed antenna structure 100) can be provided or produced.

[0083] The shape of the wire antenna element 120 may match or correspond to the shape of the border 115 of the conductive element 120. Thus, the shape of the wire antenna element may geometrically match the shape of the border 115 of the conductive element 120. Thus, the coupling between the wire antenna element and the conductive element is improved, thereby improving the efficiency of the antenna structure.

[0084] In a preferred example, the length of the first frame portion 111 plus the outline length of the gap 119 corresponds to the expected wavelength of the radio frequency signal. The outline length of the gap 119 is the total length of the edges of the gap where current is induced in the conductive element by the wire antenna element 120. For the wire radiating element shown, this includes twice the depth of the gap plus the span width of the gap, because the electric field is induced by the antenna element 120 along all edges of the gap when conducting.

[0085] In the example shown, the wire radiating element 120 is formed as a dipole antenna arrangement.

[0086] The dipole antenna arrangement comprises a first conductive element 127 formed by the first wire portion 121 and the first part 122A of the second wire portion 122. In this way, the radio frequency current in the first conductive element induces a non-negligible electric field in the first part of the gap and the first frame portion 111.

[0087] The dipole antenna arrangement further comprises a second conductive element formed by a third wire portion 123 (spatially aligned with the second frame portion 112) and a second portion 122B of the second wire portion. In this way, the radio frequency current in the second conductive element induces a non-negligible electric field in the second portion of the gap and the second frame portion.

[0088] The second conducting element 128 is oriented 180° from the first conducting element 127. Thus, the second conducting element 128 is directed or pointed in the opposite direction to the first conducting element 127.

[0089] In some examples, the antenna structure 100 may also include a pair of feed elements 171, 172. These feed elements are configured to carry RF current to the wire radiating element 120. Thus, the feed elements 171, 172 may provide an electrical connection to a RF generator (not shown) for driving the antenna structure.

[0090] In the example shown, the feed element is positioned to overlap the gap 119 of the conductive element 110. The feed element extends from the bottom of the gap 119 to the top of the gap and contacts the wire at the top. However, the feed element does not actively induce an electric field on the frame portion or the edge of the gap. In an alternative embodiment, the feed element can be oriented at 90 degrees and be in the plane of the frame 115.

[0091] Feed elements 171, 172 are connected to the dipole antenna arrangement 120 at feed points 175, 176. In the example shown, the feed points comprise a first feed point for the first part 122A of the second electric line portion and a second feed point for the second part 122B of the second electric line portion.

[0092] The distance between the feed points 175, 176 changes or modifies the bandwidth of the antenna structure. Thus, the bandwidth of the antenna structure can be tuned by defining or setting the distance between the feed points 175, 176.

[0093] The resonant frequency of the antenna structure is at least partially defined by the length of the wire antenna element. Therefore, 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 at least partially defined by the depth of the gap. This will refer to Figure 2 Detailed description.

[0094] Figure 2 The spatial relationship between the wire radiating element 120 and the conductive element 110 for a dipole antenna arrangement is conceptually illustrated. In particular, it is clearly illustrated how a portion of the wire antenna element (the second wire portion 122) is positioned to overlap the gap 119 of the conductive element 110.

[0095] The wire antenna element is formed in this configuration so that the electric field distribution induced in the conductive element 110 is located below the first frame portion 111 , both side edges and the bottom of the gap 119 , and the second frame portion 112 .

[0096] Figure 2 It is also shown how a dipole antenna arrangement can have reflection symmetry, wherein the reflection axis A of the dipole antenna arrangement R It is positioned to be spatially aligned with the gap 119 and equidistant from the first frame portion 111 and the second frame portion 112 .

[0097] The feed points 175, 176 may be positioned on the reflection axis A of the dipole antenna arrangement 120. R In other words, the feed points 175, 176 may be positioned closer to the reflection axis A than any other portion of the wire radiating element 120. R .

[0098] Figure 2 Also shown is the width W of the gap 119. g or span and the vertical height or depth D of the gap 119 g Width W g For example, it is the distance across the gap between the first frame portion and the second frame portion or in a direction away from the first frame portion 111. g is the gap perpendicular to the width W g The spacing in the direction of .

[0099] Therefore, the effective radiation length is the length L1 of the first wire portion 121, the depth D of the gap g , the width of the gap W g The depth of the gap D g The effective radiation length is the effective length of the edge of the frame that radiates the RF signal in response to the current through the wire antenna (caused by the electric field induced in the frame of the conductive element). Expressed mathematically, the effective radiation length L of the antenna structure shown is R It can be defined by the following equation:

[0100] L R =L1+L2+2Dg+Wg (1)

[0101] For improved / maximum efficiency, the radiating length is equal to half the lambda of the (desired) RF signal.

[0102] The span or width of the gap W g It can be between 10 mm and 15 mm. The vertical height or depth D of the gap g It can be between 10 mm and 20 mm. These dimensions make the gap suitable as a fraction of the radiating length of the widely used 2.4 GHz radio frequency signal.

[0103] Figure 3 The effect of feeding or providing RF current to the wire radiating element 120 is demonstrated.

[0104] In particular, the RF current (shown by small arrows) flowing through the wire radiating element 120 causes an electric field (shown by dashed arrows) to be induced in at least the first frame portion 111 and (the edge of) the gap 119. This causes the first frame portion 111 and (the edge of) the gap 119 to radiate RF signals.

[0105] Of course, for the dipole antenna arrangement shown, the RF current flowing through the wire radiating element 120 also causes an electric field (shown by dashed arrows) to be induced in at least the second frame portion 112 and the edge of the gap 119. This causes the second frame portion 112 to contribute to the radiation of the RF signal.

[0106] Figure 3 The shape of the conductive component 110 according to some examples is also shown. Specifically, the conductive component can be plate-shaped. Specifically, the conductive component can include a flat portion 310 at the bottom of the plate and a protruding portion 320 located around the edge of the flat portion 310 as a lateral edge of the plate. The protruding portion 320 can define a border of the conductive component. The flat portion 310 can be replaced by a tapered portion (e.g., a conical portion).

[0107] Figure 4 Further optional features and configuration details of the antenna structure 100 are shown.

[0108] In particular, the antenna structure 100 may include a substrate 410. The wire radiating element 120 may be positioned on the substrate 410. The conductive element 110 is coupled or fixed to the substrate such that a first wire portion of the wire radiating element is spatially aligned with a first frame portion.

[0109] In the example shown, the substrate 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 cylindrical or conical structure. The housing can be formed of any suitable material, for example, a plastic material. Preferably, the housing is formed of an electrically insulating material, such as plastic, ceramic or dielectric material.

[0110] The housing may include an opening 415 that is conformal to or sized to accommodate the border of the conductive component to receive the conductive component. The wire radiating element may be positioned along the opening of the housing so that the wire radiating element is conformal and thus aligned with the border of the conductive component.

[0111] The wire radiating element 120 may be formed on the substrate using a metal printing process, or may be formed by overmolding or otherwise attaching the wire radiating element into / onto the substrate 410. These techniques provide an antenna structure that can be easily manufactured.

[0112] In order to improve the energy coupling between the wire radiation element and the conductive element, the coupling distance (i.e., the distance between the wire radiation element and the conductive element) should be relatively low, for example, ≤5mm or ≤3mm. However, in order to maintain the spacing (e.g., to prevent / avoid arcing), preferably, the distance is not less than 0.1mm, for example, not less than 0.2mm. In some preferred embodiments, the distance between the wire radiation element and the first frame portion is between 0.5mm and 3mm.

[0113] Other features that will affect the impedance and resonant frequency of the antenna structure include the size of the gap and the length of the wire radiating element (specifically, for a dipole antenna arrangement, the length of each conductive element).

[0114] Figure 5 A luminaire 500 or lamp having a metal housing 510 of the luminaire is shown, the lamp having an antenna structure mounted in the luminaire and the metal housing 510 surrounding the lamp / antenna structure. The metal housing 500 comprises an opening for exposing the antenna structure.

[0115] In order to fully disclose Figure 5 A metal housing 510 is shown surrounding the antenna structure 100. The metal housing 510 may actually represent a housing or outer casing of a lamp / luminaire or other electronic device.

[0116] Figure 6 is a graph obtained from experimental data related to radiation efficiency, which shows that Figure 5The effect of the proposed antenna structure in the illuminator is shown in FIG. In this figure, the x-axis is the frequency f (in GHz) of the radiated signal radiated by the antenna structure, and the y-axis is the efficiency measured on a scale of 0 to 1, where 1 represents full radiation with no signal blocking and 0 represents that all signals are blocked and cannot be detected from the outside.

[0117] The first waveform 610 represents a waveform having a proposed antenna structure (e.g., Figures 1 to 4 The second waveform 620 shows the efficiency of a conventional lamp in which a conventional or standard PIFA antenna structure is placed within the housing of the lamp. In both cases, the lamp is placed Figure 5 In the luminaire structure shown in , the antenna structure is surrounded by or defined within the metal housing, and the antenna structure is positioned at the same relative position within the metal housing. It should also be noted that without the metal housing, the efficiency of the two antenna structures is similar, about 0.81 (at 2.5 GHz).

[0118] The difference between the first waveform 610 and the second waveform 620 clearly demonstrates the superior performance of the proposed antenna structure. Specifically, the efficiency of the proposed antenna structure is much greater than that of the conventional antenna structure, significantly reducing the efficiency loss (<0.1) when placed inside a metal housing.

[0119] Figure 7 It shows that Figure 4 Far-field radiation pattern of the antenna structure shown (ie, without the metal housing). Figure 8 Shown as Figure 5 Far-field radiation pattern of the electronic device depicted in .

[0120] For both radiation patterns, the value of Φ is fixed at 0 and the frequency of the radiated RF signal is 2.4 GHz. The radiated power (measured in dBi) is provided for different values ​​of θ.

[0121] Fig. 9 is a simulation diagram showing the surface current in the conductive element 110 when an electromagnetic current is fed into the wire antenna element 120. The lighter areas indicate a larger surface current than the darker areas.

[0122] Fig. 9 It is clearly shown how the surface current distribution is focused or concentrated within the first frame portion 111, the second frame portion 112 and the gap 119 (i.e., in the portion of the conductive element near the gap 119 or at the edge of the gap). It shows how these areas are activated as radiators of electromagnetic waves (i.e., radio frequency signals).

[0123] In the previously disclosed examples, the wire antenna element is formed as a dipole antenna arrangement. However, this configuration is not essential, and the wire antenna element may alternatively be configured as any other suitable wire antenna element, such as a monopole antenna or a loop antenna.

[0124] Fig.10 and Fig.11 Alternative embodiments are shown in which the wire antenna element 1020, 1120 is formed as a monopole antenna. In both embodiments, the wire radiating antenna 1020, 1120 is formed as an asymmetric antenna with a single feed point at one end of the wire radiating antenna.

[0125] Other features of the antenna structure may otherwise be the same or equivalent to any previously described embodiments.

[0126] Fig.10 An illustrative representation of the spatial relationship between the conductive element 1010 and the wire radiating element 1020 of the first monopole / asymmetric antenna structure 1000 is thus provided. The conductive element 1010 also includes a first rim portion 1011 and a gap 1019.

[0127] In the example shown, the wire radiating element 1020 is formed by a monopole antenna having a first wire portion 1021 spatially aligned with the first frame portion 1011 and a second wire portion 1022 spanning a portion of the gap 1019. Here, the portion is only a portion of the gap 1019.

[0128] The second wire portion 1022 is connected at a feed point 1075 to a single feed element 1070 that is configured to carry radio frequency signals to the wire antenna element 1020. Thus, the feed element is positioned to overlap or be spatially aligned with the gap 1019.

[0129] As shown, the conductive element 1010 may include a second border portion 1012 (wherein a gap exists between the first border portion and the second border portion). However, this is not necessary and may be omitted instead. For example, the second border portion may be replaced by a non-conductive element.

[0130] for Fig.11 For the antenna structure 1000 shown in FIG. 1 , the effective radiation length L R This can be approximated using the following equation:

[0131] L R =L 1021 +L 1022 +Dg (2)

[0132] Among them, L 1021 is the length of the first wire portion, L 1022is the length of the second wire portion, D g is the depth of the gap.

[0133] Fig.11 An illustrative representation of the spatial relationship between the conductive element 1110 and the wire radiating element 1120 of the second monopole / asymmetric antenna structure 1100 is provided. The conductive element 1110 includes a first frame portion 1111, a second frame portion 1112, and a gap 1119 spanning therebetween.

[0134] The wire radiating element 1120 also forms a monopole antenna having a first wire portion 1121 spatially aligned with the first frame 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 frame portion 1123 .

[0135] The third wire portion 1123 is connected at a feed point 1175 to a single feed element 1170 configured to carry a radio frequency signal to the wire antenna element 1120. Thus, the feed element 1175 is positioned to overlap or be spatially aligned with the second frame portion 1123.

[0136] for Fig.11 The antenna structure 1100 shown in FIG. 1 has an effective radiation length R L Can be defined in a manner similar to equation (1), wherein L1 is instead the length of the first border portion 111 overlapped by the wire radiation element 1120 (i.e., the length of the first wire portion), and L2 is instead the length of the second border portion overlapped by the wire radiation element (i.e., the length of the second wire portion).

[0137] Fig.12 is a graph derived from experimental data relating to radiation efficiency, which shows that Fig.10 and 11 The effect of the proposed antenna structure in the illuminator is shown.

[0138] In this figure, the x-axis is the frequency f (in GHz) of the radiated signal radiated by the antenna structure, and the y-axis is the efficiency Ef measured on a scale of 0 to 1, where 1 represents complete radiation with no signal blocking and 0 represents that all signals are blocked and cannot be detected from the outside.

[0139] The third waveform 1210 represents a Fig.10 The fourth waveform 1220 represents the efficiency of the lamp having the antenna structure shown in FIG. Fig.10 Efficiency of the lamp with the antenna structure represented in .

[0140] Fig.12 Show Fig.10The monopole antenna shown is able to radiate 47% of the energy from the feed point at 2.45 GHz (ie, has an efficiency of 0.47), which is significantly greater than a PIFA antenna (eg, Figure 6 shown). Fig.12 It also shows Fig.11 Shown is how the monopole antenna is able to radiate approximately 50% of the energy provided to the feed point at 2.45 GHz (ie, has an efficiency of 0.5).

[0141] This high efficiency ensures stable radiation of energy and a stable connection between a device using such energy for communication and another device receiving such energy.

[0142] Fig.13 and Fig.14 The results for different values ​​of Φ are shown. Fig.10 Far-field radiation pattern of the first monopole antenna structure (ie, without the metal housing) depicted in FIG.

[0143] Fig.15 and 16 The results for different values ​​of Φ are shown. Fig.11 Far-field radiation pattern of the second monopole antenna structure (ie, without the metal housing) depicted in FIG.

[0144] According to the radiation patterns of the two embodiments of the monopole antenna structure, the main lobe amplitude of the two antennas is greater than 4dBi. Therefore, both forms of antennas (and antenna positioning) can act as directional antennas suitable for use in metal housings.

[0145] Due to the symmetrical structure of the dipole antenna, the efficiency of the dipole antenna structure is slightly higher than that of the asymmetric monopole antenna (such as Figure 6 ). However, a monopole antenna may be employed to obtain the benefits of reduced material cost and / or smaller structure. Based on the radiation patterns of both antennas, the main lobe amplitude of both antennas is above 4dBi, and both antennas are directional antennas and can therefore be used in metal cans / enclosures.

[0146] It should be appreciated that due to the symmetrical structure of the dipole antenna, its efficiency at 2.45 GHz is higher than that of an asymmetric monopole antenna (e.g. Figure 5 However, a monopole antenna may be suitable to benefit from reduced material requirements, cost and / or space occupied by the antenna.

[0147] As previously mentioned, yet another example of a suitable wire radiating element is a loop antenna.

[0148] Fig.17 An example of an antenna structure 1700 is shown in which the wire radiating element 1720 is a loop antenna.

[0149] The loop antenna 1720 is here configured or dimensioned to follow the (entire) edge or border of the border 1715 of the conductive element 1710. This effectively enables the entire edge / border of the conductive element to contribute to the radiation of the RF signal when RF current is fed to the loop antenna 1720. The loop antenna 1720 may be coupled to one or more feed elements 1770 located at a gap 1719 defined in the conductive element.

[0150] In particular, when the shape and size of the loop antenna is set to follow the edge or border of the frame, the followed edge of the conductive element will become the main radiator of the radio frequency signal.

[0151] Fig.18 is a simulation diagram showing the surface current in the conductive element 1210 when an electromagnetic current is fed to the wire antenna element 1220 in the form of a loop antenna. The brighter area indicates a larger surface current than the darker area.

[0152] Fig.18 It is clearly demonstrated how the surface current distribution is distributed across the edge or border of the border of the conductive element 1210. Therefore, the top edge of the conductive element will become the radiator or main radiator of the electromagnetic waves representing the radio frequency signal.

[0153] However, the figure also shows how the edges of the gap also contribute to the radiation of electromagnetic waves and thus to the radiation of radio frequency signals. Thus, the effective radiation length of the entire antenna structure is increased without increasing material costs.

[0154] Exemplary dimensions of the gap have been previously described with reference to the described first embodiment, and these dimensions apply equally to the other embodiments of the present disclosure.

[0155] Other optional features of the antenna structure are described below.

[0156] In some examples where the antenna structure includes a housing, the antenna structure includes an RF (radio frequency) circuit board contained in the housing and including RF circuitry. The antenna structure may also include a connector that connects any feed element of the antenna structure to the RF circuitry. The RF circuitry may be configured to control the flow of RF current to or from the wire antenna element (via the connector and the feed element).

[0157] Any feeding element of the antenna structure may include or may be a transmission line electrically connected to the electrical wire radiating element and adapted to perform impedance matching.

[0158] An electronic device is also proposed, comprising any previously described antenna structure and a metal housing housing the antenna structure. The proposed antenna structure is particularly advantageous in this use case because it provides reduced sensitivity to the metal housing. The metal housing may have an opening on one side. The antenna structure may be positioned close to the opening to improve radiation efficiency.

[0159] Preferably, the distance between the metal shell and the conductive element of the antenna structure is not less than 5 mm, for example, not less than 10 mm. This further improves the efficiency of the antenna structure.

[0160] Preferably, the distance (D1) between the wire antenna element and the conductive element is much smaller than the distance between the wire antenna element (D2) and the metal housing. Therefore, D1<D2, for example, 5.D1<D2, for example, 10.D1<D2.

[0161] An LED lighting device may also be provided, the LED lighting device comprising the antenna structure and an LED lighting unit, the LED lighting unit being placed on the conductive element and thermally coupled to the conductive element. Specifically, the conductive element may be a heat sink for the LED lighting unit. The LED lighting unit may include one or more LEDs configured to emit light. Suitable arrangements for LED lighting units are well known in the art.

[0162] The proposed antenna structure is particularly advantageous for use in such LED lighting devices because it can configure the patterned beam of radiation output by the antenna structure to face primarily in the light direction (because the heat sink for the LED lighting unit will be positioned to align with the light direction).

[0163] If the LED lighting device comprises a metal housing, the proposed antenna structure is even more advantageous because the heat sink will naturally be positioned towards the opening of the metal housing (e.g., because this is where the light output exits), so that the patterned beam of radiation emitted by the antenna structure will be directed out of the opening in the metal housing.

[0164]

[0165] Table 1

[0166] Table 1 shows the specific advantages of using the proposed antenna structure when surrounded or surrounded by a metal housing. In particular, the impact of the housing on the total radiated power (TRP) of three different types of antenna structures is pointed out. The PIFA antenna structure is an existing antenna structure (e.g., it does not use the proposed gap-based system). The dipole antenna and loop antenna solutions have been described previously.

[0167] Table 1 clearly shows how the loss of radiated power can be significantly reduced using the proposed method when a metal housing is introduced. Table 1 also clearly shows the significant impact of the metal housing on the efficiency of the existing antenna structure.

[0168] The present disclosure recognizes that providing a gap in the border 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. Thus, the design of the gap in the conductive element can affect the frequency of the radio frequency signal.

[0169] In particular, the gap should be designed to ensure that the radiation frequency of the conductive element is the same as the operating frequency of the wire antenna element.

[0170] Perhaps the most convenient way to design or configure the gap is to evaluate the conductive element using a characteristic mode analysis technique. This can be used, for example, to find the mode of the conductive element at a desired frequency.

[0171] Variations of the disclosed embodiments may be understood and effected by those skilled in the art in practicing the claimed invention by studying the drawings, the disclosure, and the appended claims. 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.

[0172] 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.

[0173] If the term "suitable for" is used in the claims or the description, it is noted that the term "suitable for" is intended to be equivalent to the term "configured to". If the term "arranged" is used in the claims or the description, it is noted that the term "arranged" is intended to be equivalent to the term "system" and vice versa.

[0174] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. An antenna structure, comprising: A conductive component (110) having a frame (115), wherein the frame comprises a first frame portion (111) having a frame edge and a gap (119) adjacent to the first frame portion (111); as well as A wire radiation element (120) is electrically isolated from the conductive component (110), the wire radiation element comprising: a first wire portion (121) spatially aligned with the frame edge of the first frame portion (111) and extending parallel to the frame edge of the first frame portion (111); and a second wire portion (122) spanning a portion of the gap (119), Wherein, when the antenna structure is assembled and ready for operation, the frame edge is electromagnetically exposed, and the wire radiating element (120) is configured to induce an electric field in the edges of the first frame portion (111) and the gap (119) when fed with a radio frequency current, causing the electromagnetically exposed frame edge of the first frame portion (111) and the edge of the gap (119) to radiate a radio frequency signal in response to the radio frequency current fed into the wire radiating element (120).

2. The antenna structure according to claim 1, wherein: The length (L1) of the wire radiating element (120) aligned with and extending parallel to the frame edge plus the profile length of the gap (119) corresponds to the expected wavelength of the radio frequency signal, and preferably, the length (L1) of the wire radiating element (120) aligned with and extending parallel to the frame edge plus the profile length of the gap (119) is equal to half the expected wavelength of the radio frequency signal, wherein: The length of the wire radiating element (120) aligned with and extending parallel to the frame edge is between 7.5 mm and 50 mm, preferably between 7.5 mm and 45 mm, and even more preferably between 7.5 mm and 32.5 mm.

3. The antenna structure according to any one of claims 1 to 2, wherein: The frame (115) further comprises a second frame portion (112), and the gap is formed as an air gap between the first frame portion (111) and the second frame portion (112); The wire radiation element (120) further comprises a third wire portion (123), the third wire portion being spatially aligned with a frame edge of the second frame portion (112) and extending parallel to the frame edge of the second frame portion; and The length of the frame edges of the first frame portion (111) and the second frame portion (112) plus the outline length of the gap (119) corresponds to the expected wavelength of the radio frequency signal, The profile length of the gap (119) includes the depth (D g ) plus the width of the gap (W g ).

4. The antenna structure according to claim 3, wherein: The wire radiating element comprises a dipole antenna arrangement, the dipole antenna arrangement comprising: a first conductive element, comprising the first wire portion (121) and a first portion (122A) of the second wire portion, and the first conductive element is configured such that a radio frequency current in the first conductive element induces a non-negligible electric field in the first frame portion and a first portion of the gap; and A second conductive element, which is oriented 180° from the first conductive element, includes the third wire portion (123) and a second portion (122B) of the second wire portion, and the second conductive element is configured so that the radio frequency current in the second conductive element induces a non-negligible electric field in the second frame portion and the second portion of the gap.

5. The antenna structure according to claim 4, wherein: The dipole antenna arrangement has reflection symmetry, wherein: The reflection axis (A) of the dipole antenna arrangement R ) is positioned to be spatially aligned with the gap (119) and equidistant from the first frame portion (111) and the second frame portion (112); and The dipole antenna arrangement comprises a pair of feed points at a reflection axis of the dipole antenna arrangement.

6. The antenna structure according to any one of claims 1 to 3, wherein: The wire radiating element is a monopole antenna having a feed point at one end of the wire radiating element.

7. The antenna structure according to any one of claims 1 to 6, wherein: The distance between the wire radiation element and the frame edge of the first frame portion is between 0.5 mm and 3 mm.

8. The antenna structure according to any one of claims 1 to 7, wherein: The gap is rectangular, trapezoidal or triangular in shape, and when the gap is rectangular in shape, the span (W g ) is between 10 mm and 15 mm, and The vertical height or depth of the gap perpendicular to the span (D g ) is between 10mm and 20mm.

9. The antenna structure according to any one of claims 1 to 8, further comprising a substrate (410), wherein: The wire radiating element (120) is located on the substrate; and The conductive member (110) is fixed to the substrate so that the first wire portion and the frame edges of the first frame portion of the wire radiating 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 that accommodates and holds the conductive component.

11. The antenna structure according to claim 10, further comprising: an RF circuit board housed in the housing and including an RF circuit; a feed element formed on the housing and electrically connected to the wire radiating element; as well as A connector connects the feeding element and the RF circuit.

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

13. The antenna structure according to any one of claims 10 to 12, wherein: The conductive component is plate-shaped; The housing is cup-shaped or cylindrical, and includes an opening conforming to the frame of the conductive component for receiving the plate-shaped conductive component; and The wire radiating element is positioned along the opening of the housing such that the wire radiating element is conformal and thereby aligned with the border of the conductive element.

14. The antenna structure according to any one of claims 1 to 13, wherein: The conductive component is a heat sink.

15. An LED lighting device, comprising: The antenna structure of claim 14; as well as The LED lighting unit is disposed on the heat sink and thermally coupled to the heat sink.

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