An antenna arrangement for a watercraft

Abstract

An antenna arrangement for a watercraft is disclosed. In an embodiment, the antenna arrangement comprises a first antenna configured to wirelessly communicate with a wireless user device, the first antenna for securement to a top-side of a watercraft; a second antenna configured to wirelessly communicate with a wireless control unit, the second antenna for securement to an underside of the watercraft to place the second antenna in juxtaposed relationship with a third antenna of a wireless control unit; and a radio frequency (RF) transmission line conductively coupling the first antenna and the second antenna.

Description

AN ANTENNA ARRANGEMENT FOR A WATERCRAFTPRIORITY CLAIM

[0001] The present application for patent claims priority from Australian Provisional Patent Application No. 2024901552 entitled “AN ANTENNA ARRANGEMENT FOR A WATERCRAFT", filed 24 May 2024, which is hereby expressly incorporated by reference herein in its entirety.FIELD

[0002] The present disclosure relates to an antenna arrangement. In a typical application an embodiment of the present disclosure may be used with a watercraft.BACKGROUND

[0003] Watercraft based activities using small vessels, such as surfing, kite-surfing, stand-up paddle boarding and kayaking, are popular outdoor recreational pursuits. However, these activities can place relatively significant fitness and endurance demands on the person involved with the activity. For example, surfing involves paddling at moderate intensity from a beach to a break, and then burst-type efforts of paddling at a higher intensity to try and catch a wave. Unfortunately, the fitness and endurance demands of surfing may dissuade people from participating or otherwise limit their participation. Similarly, because of its own particular set of physical demands, conventional stand-up paddle boarding involving a board and a paddle for generating propulsion may also only be suitable for people of reasonable fitness, endurance and strength.

[0004] To reduce the demands placed on people who might enjoy watercraft based activities such as surfing and stand-up paddle boarding, electric propulsion systems have been developed which involve attaching an electric motor to a paddle or surfboard and providing a separate control unit for operating the electric motor to vary thrust which may either supplement the user’ s self-generated propulsion, or it may provide the only source of propulsion when required. In either case, the electric propulsion system may enhance the user’s experience of the activity by providing an additional propulsion option which may replace or reduce the user’s propulsive effort.

[0005] In such systems, the electric motor may be controllably operated by an operator of the watercraft using a user device which communicates a communication signal to the control unit to control the electric motor.

[0006] In some existing electric propulsion systems for board type watercraft, communication between the user device and the control unit involves a wired connection between the user device and a control unit which is located either in a compartment in the board or on an underside of the board. In such an arrangement, the user operates the user device to communicate communication signals to the control unit via a wired communication link to vary the amount of thrust provided by the electric motor. Unfortunately, operating a wired user device restricts the freedom of movement of the user and thus may interfere with the user's operation and enjoyment of the board.

[0007] Wireless systems have been developed which support communication of a wireless signal between a wireless user device and a wireless control unit located on an underside of the board so that the board is located between the wireless user device and the wireless control unit when the board is in use. However, such systems may provide a degraded communication link between the wireless user device and the wireless control unit in circumstances where the board is constructed from a material which strongly attenuates wireless signals propagating through them. In such circumstances, a reliable radio link may not be able to be established between the control unit and the user’s controller.

[0008] It would be desirable to provide a system for communicating between a wireless control unit which is attached to a hull of a watercraft and a wireless user device which is remote from the wireless control unit which overcomes at least some of the above deficiencies of existing approaches.SUMMARY

[0009] In general terms, embodiments of the present disclosure provide an antenna arrangement for a watercraft which provides a signal path for conducting communication signals between a wireless user device in signal communication with a first end of the antenna arrangement and a wireless control unit in signal communication with a second end of the antenna arrangement using a wireless communication link at each end of the antenna arrangement, and a RF transmission line which conductively couples the ends of the antenna arrangement.

[0010] In certain embodiments, the antenna arrangement comprises a pair of antennas which are conductively coupled by the RF transmission line. In use, a first antenna of the pair is secured to a topside (or deck) of the watercraft to wirelessly communicate with the wireless user device. A second antenna of the antenna arrangement is secured to an underside of the watercraft, being the hull of the watercraft, in juxtaposed relationship with the wireless control unit to wirelessly communicate with the wireless control unit using a near-field electromagnetic coupling. The RFtransmission line conducts communication signals between the first antenna and the second antenna by wired communication. In one embodiment, the RF transmission line supports bidirectional wired communication between the first antenna and the second antenna.

[0011] An advantage of embodiments of the present disclosure is that by replacing a wholly wireless signal path with a partly-wired partly-wireless signal path between the wireless user device and the wireless control unit, the partly-wired component (ie, the RF transmission line) of the signal path can be routed to conduct communication signals around or through media, such as conductive media, which would otherwise attenuate wireless communication signals.

[0012] According to a first aspect of an embodiment of the present disclosure, there is provided an antenna arrangement for a watercraft comprising: a first antenna configured to wirelessly communicate with a wireless user device, the first antenna for securement to a top-side of the watercraft; a second antenna configured to wirelessly communicate with a wireless control unit, the second antenna for securement to an underside of the watercraft to place the second antenna in juxtaposed relationship with a wireless control unit; and a radio frequency transmission line conductively coupling the first antenna and the second antenna.

[0013] In an embodiment, the first antenna and the second antenna are passive antennas.

[0014] In an embodiment, the first antenna is configured to wirelessly communicate through air. The first antenna may be configured for wireless communication with the wireless user device using a short-range wireless communications protocol. Examples of short-range wireless communications protocols include Bluetooth™, Zigbee™, and WiFi.

[0015] In one arrangement, the first antenna is encapsulated within a body which protects the first antenna from moisture.

[0016] The first antenna may be any type of antenna which is able to wirelessly communicate with the wireless user device. One example of a suitable antenna type is a patch antenna. However, it is possible that other types of antennas may be used for the first antenna. Other examples of suitable antenna types include a circular or rectangular patch antenna, a shorted quarter-wavelength patch antenna, a dipole antenna, a monopole antenna, a tee antenna, an inverted-F antenna, a loop antenna, or a notch antenna.

[0017] In an embodiment, the second antenna is configured for wireless communication with an antenna (which, in the context of this description, is a third antenna) of the wireless control unit. The second antenna may be enclosed or encapsulated by a laminar structure which protects thesecond antenna from moisture. The laminar structure may be in the form of a planar laminar structure.

[0018] In embodiments, the second antenna is configured for wireless communication with the third antenna using a near-field electromagnetic coupling. In an embodiment, the second antenna comprises a coplanar waveguide fed strip antenna. However, it is to be appreciated that other types of antennas which allow electromagnetic coupling with the antenna of the wireless control unit may be used.

[0019] The laminar structure which encloses or encapsulates the second antenna may have a first major surface for contacting an underside of the watercraft and a second major surface for contacting an opposing surface of a housing of the wireless control unit when the second antenna is secured between the underside of the watercraft and the housing of the wireless control unit. In an embodiment, the first major surface and the second major surface are on opposite faces of the second antenna.

[0020] The first antenna may be configured to re-transmit a RF signal wirelessly received by the second antenna and communicated to the first antenna by the RF transmission line.

[0021] The second antenna may be configured to re-transmit a RF signal wirelessly received by the first antenna and communicated to second antenna by the RF transmission line.

[0022] In certain embodiments, the RF transmission line is a flexible transmission line.

[0023] In certain embodiments, the RF transmission line is a coaxial cable.

[0024] In certain embodiments, the RF transmission line comprises a flexible strip.

[0025] In certain embodiments, the RF transmission line is a printed transmission line.

[0026] In certain embodiments, the RF transmission line comprises a passive transmission line and a bidirectional amplifier.

[0027] Yet another aspect of an embodiment of the present disclosure provides a watercraft incorporating an antenna arrangement according to the above-described aspect.

[0028] Still another aspect of an embodiment of the present disclosure provides a propulsion system for a watercraft, comprising: an antenna arrangement according to the above described aspect; a wireless control unit including an antenna configured to wirelessly communicate with the second antenna of the antenna arrangement, the wireless control unit further comprising a motor controller for controlling an electric motor in coupled communication with the motorcontroller depending on communication signals communicated by the second antenna to the antenna; and means for securing the wireless control unit to the underside of the watercraft such that when so secured the second antenna is clamped between the wireless control unit and the underside of the watercraft to place the second antenna in juxtaposed relationship with the antenna of the wireless control unit.

[0029] Still another aspect of the present disclosure provides a watercraft comprising: a board having a hull; a propulsion unit for propelling the board; an antenna arrangement comprising: a first antenna located on a top-side of the board; a second antenna located on an underside of the hull; a radio frequency transmission line conductively coupling the first antenna to the second antenna to conduct communication signals between the first antenna and the second antenna; and a wireless control unit located on the underside of the hull, the wireless control unit incorporating a third antenna configured for coupled communication with the second antenna, the wireless control unit configured to control the propulsion unit depending on one or more communication signals received by the first antenna and communicated to the second antenna; wherein the second antenna is located proximal to the third antenna to allow wireless communication therebetween.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] For better understanding of the invention and to show how it may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention, with reference to the accompanying drawings wherein:

[0031] Figure 1 is a simplified functional block diagram of an antenna arrangement according to an embodiment of the present disclosure;

[0032] Figures 2 and 3 are schematic diagrams of an antenna configuration suitable for a first antenna of an antenna arrangement according to an embodiment of the present disclosure;

[0033] Figure 4 is schematic diagram of an antenna configuration suitable for a second antenna of an antenna arrangement according to an embodiment of the present disclosure;

[0034] Figure 5 is a bottom view of a second antenna incorporating the antenna configuration shown in Figure 4;

[0035] Figure 6 is a perspective bottom view of the second antenna shown in Figure 5;

[0036] Figure 7 is a perspective exploded view showing the second antenna of Figure 5 with a wireless control unit;

[0037] Figure 8 is a perspective exploded view of a watercraft incorporating an antenna arrangement according to an embodiment;

[0038] Figure 9 is a partial side view of the watercraft shown in Figure 8; and

[0039] Figure 10 is a perspective view of the watercraft shown in Figure 8.DETAILED DESCRIPTION OF EMBODIMENTS

[0040] Embodiments of the present disclosure provide an antenna arrangement for use with a watercraft. In the described embodiment, the antenna arrangement provides a signal path which supports signal communications between a wireless user device operated by a user situated on a top-side or deck of the watercraft and a wireless control unit secured to an underside of the watercraft.

[0041] The antenna arrangement described below includes a radio frequency (RF) transmission line which conducts communication signals between a first antenna secured to the topside of the watercraft and a second antenna positioned in juxtaposed relationship with a wireless control unit secured to the underside of the watercraft.

[0042] Embodiments of the present disclosure may be used with a watercraft having a hull construction or other features of a conductive material which could attenuate wireless signals propagating therethrough to such an extent as to at least partially degrade wireless communication between the wireless user device and the wireless control unit.

[0043] An advantage of embodiments of the present disclosure is that they provide an alternative signal path which circumvents a high attenuation signal propagation path through the hull (or other features of a conductive material which could attenuate wireless signals) of the watercraft.

[0044] Before continuing further, the below description describes an embodiment in relation to an application which involves a watercraft in the form of a motorised board (such as a surfboard, a sailboard, a wake board, or a standup paddle board) having a wireless control unit which is secured to an underside of the board. However, it will be appreciated that embodiments of the present disclosure may also be used with other types of watercraft. Non-limiting examples ofother types of watercraft include a power boat, sail craft, kayak, or canoe. Indeed, it is envisaged that embodiments of the present disclosure may be used with any watercraft having a hull to which a wireless control unit for an electric motor is attached and which is configured to normally receive and / or transmit wireless communication signals to and / or from a wireless user device operated by a user situated on a top-side or deck of the watercraft.

[0045] In the described embodiment, when the motorised board is in normal use, the first antenna of the disclosed antenna arrangement is configured to wirelessly communicate with the wireless user device, the second antenna is configured to wirelessly communicate with the wireless control unit, and the first antenna and the second antenna are conductively coupled by the RF transmission line to communicate signals between the first antenna and the second antenna.

[0046] In some embodiments, the disclosed antenna arrangement provides a signal path which supports communication between the wireless user device and the wireless control unit and which enables signal communication around, as opposed to through, the hull of the watercraft.

[0047] Figure 1 shows a simplified functional block diagram for a watercraft 1 in the form of a motorised board having an antenna arrangement 10 according to an embodiment of the present disclosure. An example configuration of the watercraft 1 is illustrated in Figures 8 to 10.

[0048] In the illustrated embodiment, the watercraft 1 comprises a board 2, a hydrofoil assembly 14 demountably secured to a hull 5 of the board 2, a propulsion unit 8 attached to the hydrofoil assembly 14, and a wireless control unit 12. The watercraft 1 shown here is intended for use as a motorised standup paddle board or surfboard which is capable of operating in a foiling or nonfoiling mode. In the embodiment shown in Figures 8 to 10, the wireless control unit 12 is demountably secured to an underside 103 of the hull 5 of the board 2. In this configuration, the wireless control unit 12 would be submerged when the watercraft 1 is in use and operating in a non-foiling mode.

[0049] The antenna arrangement 10 is configured to provide a signal propagation path which supports communication between a wireless user device 6 and the wireless control unit 12 in way which does not rely on signal transmission through the board 2 to control operation of the propulsion unit 8. By providing a signal propagation path which supports signal communication between the wireless user device 6 and the wireless control unit 12 which does not rely on signal transmission through the board 2, embodiments of the present disclosure may provide more reliable communication compared to arrangements which require signal transmission through the board 2. In arrangements which require signal transmission through the board 2, signalcommunication could be severely impaired if, for example, the construction of the board 2 contained conductive materials such as carbon fibre reinforced plastic. Embodiment of the present disclosure provides for the use of antenna arrangement 10 attached to board 2 which may overcome this limitation.

[0050] In the present case, the illustrated antenna arrangement 10 comprises a first antenna 16 located on a top-side 102 (which in this example is the deck of the board 2), a second antenna 18 located on an underside 103 of the hull 5 of the board 2, and a RF transmission line 20 which conductively couples the first antenna 16 to the second antenna 18 to conduct communication signals between the first antenna 16 and the second antenna 18.

[0051] Propulsion unit 8 comprises an electric motor 28 and propeller 30. Electric motor 28 is in coupled communication with the wireless control unit 12 via a suitable electrical cable 34. In the present case, the wireless control unit 12 is configured to control the electric motor 28 in coupled communication with the wireless control unit 12 by means of one or more wireless signals received by an antenna 25 of the wireless control unit 12 from the second antenna 18.

[0052] As shown in Figure 8, the propulsion unit 8 is attached to a mast element 4 of the hydrofoil assembly 14. The mast element 4 has a top section including a plate member 60 for receiving fastening means 96 for demountably securing the plate member 60, and thus the hydrofoil assembly 14, to the underside 103 of the hull 5. In the illustrated arrangement, the second antenna 18 and the wireless control unit 12 are clamped between the plate member 60 and the underside 103 of the hull 5 when the plate member 60 is demountably secured to the underside 103 of the hull 5.

[0053] In the illustrated embodiment, wireless user device 6 may be operated by a user to transmit a communication signal S using a wireless communication protocol which encodes information for communication to the wireless control unit 12 via the antenna arrangement 20. The wireless user device 6 and the wireless control unit 12 may employ a short-range wireless communication protocol such as Wi-Fi, Bluetooth™, or ZigBee™ to wirelessly communicate with the first antenna 16.

[0054] In the present case, communication signals transmitted to and received by the first antenna 16 are coupled between antenna 16 and antenna 18 by means of RF transmission line 20 and thence via antenna 25 to control unit 12. In some embodiments, the wireless communication protocol may use a 2.4-GHz signal having a transmission power of between 1 mW and 10 mW.

[0055] Communication signal S may comprise control or status signals encoding information for communication between the wireless user device 6 and the wireless control unit 12. Examples ofsuch signals include signals encoding information for communication from the wireless user device 6 to the wireless control unit 12, via the antenna arrangement 10, for adjusting or setting the thrust or operating mode of the electric motor 28, and signals for communication from the wireless control unit 12 to the wireless user device 6, via the antenna arrangement 10, encoding information indicating, for example, a status of the wireless control unit 12, such as the status of a battery of the wireless control unit 12, motor operating temperature or the like.

[0056] As shown in Figure 1, the illustrated wireless control unit 12 includes an antenna 25 (being a third antenna), a signal receiver and processing unit 26 in coupled communication with the antenna 25, and a power supply 27 (such as a battery). Wireless control unit 12 has a housing 106 which provides a sealed internal volume shaped to receive the power supply 27 and the signal receiver and processing unit 26 (ref. Figure 1). The power supply 27 and signal receiver and processing unit 26 may be conductively connected by wires or demountable connectors, or may be partly or wholly configured as an assembly.

[0057] In the illustrated example, the signal receiver and processing unit 26 processes communication signal received by the antenna 25 to provide a motor control signal which varies or sets the speed of the electric motor 28. Motor 28 varies the thrust generated by a propeller 30 of the propulsion unit 8 depending on the motor control signal. One example of a wireless control unit 12 is described in International Patent Publication WO 2023 / 159276 Al titled “Watercraft Propulsion System” the contents of which are herein incorporated by reference.

[0058] The transmission line 20 may comprise any RF transmission line suitable for conducting communication signals between the first antenna 16 and the second antenna 18. In the present case, the RF transmission line 20 is configured to conduct communication signals having a frequency within a first range of frequencies. As will be described in more detail below, in certain embodiments, the first antenna 16 and the second antenna 18 are independently matched to the impedance of the RF transmission line 20 which is typically 50 ohms.

[0059] It will be appreciated that the choice, configuration, or matching of the first antenna 16 at one end of the RF transmission line 20 may be independent of the choice, design, or matching of the second antenna 18 at the other end of the RF transmission line 20. Impedance matching may be carried out with a matching network comprising components or traces, as would be well understood by a person skilled in the art.

[0060] The transmission line 20 in the illustrated embodiment is a coaxial cable or a microcoaxial cable. However, in some embodiments, the RF transmission line 20 may comprise a strip such as a printed transmission line. In certain embodiments, it is possible that the antennaarrangement 10 includes suitable electronic circuit arrangements, such as fibre optic transceivers, for interfacing the first antenna 16 and the second antenna 18 to a transmission line in the form of a fibre optic transmission line.

[0061] In one embodiment, conductively coupling the first antenna 16 to the second antenna 18 via the RF transmission line 20 involves terminating a first end 22 of the RF transmission line 20 to a feed point 70 (ref. Figure 2) of the first antenna 16 and terminating a second end 24 of the RF transmission line 20 to a feed point 82 (ref. Figure 4) of the second antenna 18 using suitable terminations. One example of a suitable termination comprises soldered terminations.

[0062] In an embodiment, an adhesive is applied to a surface of each of the first antenna 16, the second antenna 18 and the RF transmission line 20 to secure them to the board 2. One example of a suitable adhesive is a waterproof adhesive tape. In embodiments, the RF transmission line 20 should have a bend radius and sufficient flexibility to allow the RF transmission line 20 to be secured to and generally conform with the shape of the board 2 when secured thereto.

[0063] In some arrangements, the first antenna 16, the second antenna 18 and the RF transmission line 20 are formed as an integrated one-piece construction which does not require any demountable terminations to conductively connect the first antenna 16 to the second antenna 18 via the RF transmission line 20. For example, in one embodiment the first antenna 16, the second antenna 18 and the RF transmission line 20 are formed on a continuous substrate such as a flexible printed circuit board (PCB). In an embodiment in which the antenna arrangement 10 comprises an integrated one-piece device, an adhesive may be applied to a surface of the integrated one-piece device to secure the integrated one-piece device to the board 2.

[0064] As shown in Figure 1, in the illustrated embodiment the first antenna 16 is secured to a top-side 102 of the board 2 from where it is able to wirelessly communicate with the wireless user device 6 using through air communication.

[0065] In the present case, the first antenna 16 is secured to an area of the top-side of the board 2 which is located proximal to a bow or front of the board 2 by suitable means. However, it is possible that the first antenna 16 could be located at a different position on the top-side 102 of the board 2. An advantage of locating the first antenna 16 proximal to the bow or front of the board 2 is that it is clear of an area of the top-side 102 of the board 2 on which the user of the board 2 normally stands, sits or lies and thus is less likely to interfere with or be obstructed by the user of the board 2 in use.

[0066] With reference now to Figures 2 and 3 there is shown a configuration of a first antenna 16 suitable for use with an antenna arrangement 10 according to an embodiment of the presentdisclosure. The illustrated first antenna 16 shown here comprises a patch antenna 36 which is encapsulated within a disc or puck shape body 62. Body 62 may be formed from a thermoplastic such as polycarbonate or polystyrene and may conveniently be made by a process such as injection moulding. Alternatively, the body 62 may be produced by a 3-D printing process in a material suited to that form of manufacture, such as nylon PA6 or PA12.

[0067] In the present case, the body 62 comprises an upper member 58a and a lower member 58b which provide a dielectric housing which is formed by joining the upper member 58a and the lower member 58b during assembly of the first antenna 16 to enclose or encapsulate the patch antenna 36. A coating of encapsulating resin, such as an epoxy resin may be applied to the patch antenna 36 and other components located within the body 62 during assembly to reduce the risk of water ingress.

[0068] The patch antenna 36 shown here comprises a conductive resonating patch 68 formed on an upper surface 38 of a dielectric substrate 40. Resonating patch 68 may comprise a thin layer of conductive material, such as copper or gold, having a geometry which provides the required operating frequency and radiation characteristics for the patch antenna 36 to wirelessly communicate with the wireless user device 6. In the present case, the patch antenna 36 has four comers 42 which are shaped to reduce the diagonal dimensions of the patch antenna 36 and thus the diameter of the disc or puck-shaped body 62 enclosing or encapsulating the patch antenna 36.

[0069] An advantage of using a patch antenna 36 as the first antenna 16 is that it allows the first antenna 16, and associated strain relief arrangements, to be contained within a relatively robust, compact and low-profile body 62 which is unlikely to impair the movement of a user, be damaged by the user, or cause discomfort or injury to the user. However, it is possible that other types of antenna configurations may be used. Examples of other types of antennas which may be suitable include a circular or rectangular patch antenna, a shorted quarter-wavelength patch, a dipole antenna, a monopole antenna, a Tee antenna, or an inverted-F antenna. It is possible that other types of antennas may also be suitable.

[0070] Continuing now with reference to Figure 2, there is a ground area 44 formed on the upper surface 38 of the dielectric substrate 40 as a conductive layer. This ground area 44 is conductively connected to a conductive ground plane which substantially entirely extends across a lower surface 48 of the dielectric substrate 40. In the present case, this conductive connection is by way of plated-through holes 46 formed within the ground area 44.

[0071] Two notches 52, 54 are formed on an edge of the patch antenna 36 proximate to ground area 44. The notches 52, 54 are spaced equidistantly about a centreline C of the patch antenna36 and are sized to set the input impedance characteristic of the patch antenna 36 to ensure that, in conjunction with the choice of the length and width of the resonating patch 68, the patch antenna 36 is matched to the characteristic impedance of the RF transmission line 20 at the radio frequencies to be employed for communication with the wireless user device 6 and the wireless control unit 12. Techniques for sizing the notches 52, 54 and the resonating patch 68 would be within the knowledge of a skilled person.

[0072] In an embodiment, RF transmission line 20 is a coaxial transmission line having a signal conductor 64 (ref. Figure 3) which, at the first end 22 of the transmission line 20, is conductively terminated to a feed point 70 on the patch antenna 36 located between notches 52, 54. An outer conductor 66 of the RF transmission line 20 is conductively terminated to ground area 44. In the illustrated embodiment, both of these conductive terminations are made by soldering although other termination techniques may be used.

[0073] In some embodiments strain relief is provided at the junction of the RF transmission line 20 with the body 62 such as by curving or meandering the path of the RF transmission line 20 and / or by protecting the RF transmission line 20 with a suitable resilient sleeve, such a sleeve of a heat-shrink tube. Suitable strain relief arrangements would be well understood by a skilled person.

[0074] Returning now to Figure 1, the second antenna 18 is configured for securement between an underside of the board 2 and the wireless control unit 12 to position the second antenna 18 in juxtaposed relationship with an antenna 25 (which in this example is a slot antenna) which, in the present case, is integrated into a top planar section of a housing 106 of the wireless control unit 12 to facilitate near-field electromagnetic coupling therebetween.

[0075] In the present case, and as will be described in more detail below, the second antenna 18 comprises a laminar structure configured for securement between the underside 103 of the hull 5 of the board 2 and an upper planar surface 32 of the housing 106 (ref. Figure 7) of the wireless control unit 12 so that, when so secured, the second antenna 18 is clamped between the wireless control unit 12 and the underside 103 of the hull 5 of the board 2 to place antenna circuitry 90 (ref. Figures 5 to 7) of the second antenna 18 in a juxtaposed relationship with the antenna 25 of the wireless control unit 12.

[0076] Figure 4 shows an embodiment of an antenna circuit 90 suitable for use in the second antenna 18. In the present case, the antenna circuit 90 is configured to form a coplanar waveguide fed strip antenna. However, it will be appreciated that the configuration of the second antenna 18 could be varied depending on the configuration of the antenna 25 in thewireless control unit 12. For example, in one embodiment, the antenna 25 is a slot antenna, aligned with elongate window 50 in the upper surface of housing 106 and the second antenna 18 is configured to electromagnetically couple with the slot antenna of the wireless control unit 12.

[0077] The illustrated coplanar waveguide fed strip antenna comprises a first conductive element 72 disposed on a first face 74 of a dielectric substrate 76. The first conductive element 72 may be formed from, for example, 0.8-mm thick copper-clad printed circuit laminate by means of a conventional etching process.

[0078] The conductive element 72 shown here comprises a first elongate section 78 and a second elongate section 80 which extends perpendicularly from the first elongate section 78 in the direction of an antenna feed 82. The first elongate section 78 terminates at an open circuit located at a first end 81 of the conductive element 72. As shown in Figure 6, when the wireless control unit 12 is demountably secured to the underside 103 of the hull 5, the second antenna 18 is located such that conductive element 80 has a direction orthogonal the longitudinal axis of the window 50 provided in the upper surface 106 of wireless control unit 12.

[0079] In the present case, the length (LI) and width (Wl) of the first elongate section 78 and the second elongate section 80 (L2, W2) are selected to provide a required operating frequency and radiation characteristics which permits wireless communication with the antenna 25 of the wireless control unit 12.

[0080] In this respect, it has been found that a first elogate section having length (LI) of about 30 mm long and a width (Wl) about 3 mm wide, and a second elogate section having a length (L2) of about about 25 mm long with a width (W2) of about 1 mm will support operation at a frequency in the range of 2.4-2.485 GHz. However, other length and width dimensions may also be used. Furthermore, it is to be appreciated that different antenna configurations may be used, including, for example an antenna configuration in which the first elongate section 78 is arranged in colinear relationship with the second elongate section 80. Indeed, the configuration of the depicted second antenna 18 may be varied according to the construction of the housing 106 and / or for improved communication with an antenna 25 of the wireless control unit 12.

[0081] Continuing with reference to Figure 4, there is a conductive ground area 86 formed on the first face 74 of the dielectric substrate 76. An area 92 of the dielectric substrate 76 without conductive material thereon surrounds the first conductive element 72 and separates it from the ground area 86.

[0082] An open slot shaped region 88 is formed in the conductive ground area 86. At least an extent of the second segement 80 projects into slot shaped region 88 with a clearance thereaboutsto provide a radio frequency transmission line in the form an elongate end-fed conductive strip fed by means of a coplanar waveguide.

[0083] Feed point 82 is located at an end 84 of the conductive element 72. The signal conductor 64 of the RF transmission line 20 is conductively terminated to the feed point 82 of the coplanar waveguide fed strip antenna 90 whereas outer conductor 66 of the RF transmission line 20 is conductively terminated to the ground area 86 by soldering and / or the use of a mechanical clamp.

[0084] Figures 5 to 7 show an an embodiment of the second antenna 18 which includes the antenna circuit 90 described above. As shown in Figure 7, the antenna circuit 90 shown in Figure 4 is enclosed or encapsulated in a laminar structure so that the second antenna 18 has a perimeter shaped to correspond with at least a portion of the upper surface 32 (ref. Figure 7) of the housing 106.

[0085] To form the laminar structure of the second antenna 18, each face of the antenna circuit 90 is covered by a lamina of high-density polyethylene or a similar dielectric material, attached by a suitable double- sided adhesive film or other adhesive to provide protection to the coplanar waveguide fed strip antenna and seal the antenna circuit 90 from moisture in normal use.

[0086] In this arrangement, and as shown in Figures 8 and 9, when the second antenna 18 is secured to the underside 103 of the board 2, the second antenna 18 is substantially covered and thus generally concealed by the upper surface 32 of the housing 106. Such an arrangement is expected to not significantly affect the contribution of the second antenna 18 to hydrodynamic drag as the board 2 moves at speed through water.

[0087] In the present case, the second antenna 18 is secured between the underside 103 of the hull 5 and the housing 106 of the wireless control unit 12 by clamping the second antenna 18 between the housing 106 and the underside 103 of the hull 5 to secure the second antenna 18 in juxtaposed relationship with the antenna 25. In certain embodiments, when so clamped the upper surface 32 of the housing 106 is held in interfacial relationship with the second antenna 18 to restrict moisture ingress there between. In some embodiments, a protective cover, gasket or sealing means is positioned between or around the interface between the second antenna 18 and the housing 106 to further improve moisture protection.

[0088] Continuing now with reference to Figure 7, the second antenna 18 includes apertures 94 (shown here as slots) which are positioned to allow fasteners 96 (ref. Figure 8) used to secure the housing 106 to the board 2 to pass through the second antenna 18 and engage with securement means 98 such as threaded apertures 98.

[0089] In embodiments, when the second antenna 18 is secured between the underside 103 of the hull 5 and the housing 106 of the wireless control unit 12, a positional relationship between the second antenna 18 and the housing 106 is established which places the second antenna 18 in proximity to, and at least a partial overlapping relationship with, the antenna 25 of the wireless control unit 12 to allow wireless communication therebetween.

[0090] As shown in Figure 7, in the illustrated embodiment a window 50 which is transparent to wireless signal communication at the frequency of the communication signal S is provided within the upper surface 32 of housing 106. In other words, the window 50 permits propagation of wireless communications to the antenna 25 without significant attenuation to allow wireless communication between the second antenna 18 and the antenna 25 of the housing 106. Window 50 may be filled and sealed against water ingress by means of a suitable dielectric encapsulating material such as an epoxy resin.

[0091] In the present case, the antenna 25 is positioned within dielectric-filled window 50 and antenna 18 is positioned in a partial overlapping relationship with the window 50 of the wireless control unit 12 to allow wireless communication with the antenna 25 through the dielectric-filled window 50. In the present embodiment the window 50 is provided within the upper surface 32 of conductive housing 106 to permit electromagnetic coupling between the second antenna 18 and the antenna 25. In other embodiments it is possible that the entire housing 106 or its upper surface 32 is constructed of a material which is transparent to wireless signal communication at the frequency of the communication signal S in which case different antenna configurations may be used for the second antenna 18 and the antenna 25.

[0092] In a present embodiment, the antenna 25 is encapsulated in the window 50 and has a general configuration known to those skilled in the art as a ‘slot antenna’ formed on a substantially planar dielectric substrate having an upper surface and a lower surface. In an embodiment, the antenna 25 is fabricated using copper-clad dielectric laminate using an industry-standard etching process.

[0093] In embodiments which include a slot antenna positioned within window 50, the configuration of the slot antenna may be chosen based on the geometry of the window 50 to allow communication of a signal which is polarised in a direction across the narrow dimension of the window 50. In one embodiment, the slot in the upper surface of the antenna 25 is approximately a half wavelength long, for example 50 mm x 6 mm for an operating frequency of 2.4-2.485 GHz. In this configuration the window 50 in the housing 106 should be at least as large in both dimensions as the slot in the antenna 25.

[0094] In other embodiments the upper surface 32 of housing 106 may be formed from non- conductive dielectric material such as a thermoplastic material, for example polycarbonate or glass-loaded nylon, in which case no separate window 50 may be required and alternative antenna configurations may be used for antennas 18 and 25, for example a dipole or inverted-F antennas.

[0095] Referring now to Figure 10, wireless user device 6 (shown here as attached to a paddle) may be operated by a user situated on the top-side 102 of the board 2 to transmit a communication signal S encoding commands for communication to the wireless control unit 12. These commands may include, for example, commands which adjust or set the thrust or operating mode of an electric motor 28 in coupled communication with the wireless control unit 12.

[0096] First antenna 16 is secured to the top-side 102 of the board 2 where it is able to receive and / or transmit communication signals from and / or to wireless user device 6 through air. In the present case, the second antenna 18 is secured between the underside 103 of the board 2 and the wireless control unit 12 in a juxtaposed relationship which places the second antenna 18 in proximity to, and at least a partial overlapping relationship with, the antenna 25 (ref. Figure 7) of the wireless control unit 12 to allow near-field electromagnetic coupling therebetween.

[0097] Second antenna 18 is secured between the underside 103 of the hull 5 and the housing 106 of the wireless control unit 12 by clamping the second antenna 18 between the wireless control unit 12 and the underside 103 of the hull 5 to place the second antenna 18 in juxtaposed relationship with the antenna 25 of the wireless control unit 12. In the present example the second antenna 18 comprises the antenna circuit 90 described above. When clamped in this way, an upper surface of housing 106 is held in interfacial relationship with the second antenna 18 to restrict moisture ingress there between. In some embodiments, a protective cover, gasket or sealing means is positioned within or around the interface between the second antenna 18 and the housing 106 to further improve moisture protection.

[0098] RF transmission line 20 is secured to the board 2 and conductively couples the first antenna 16 to the second antenna 18 to conduct wireless communication signals between the first antenna 16 and the second antenna 18. In the present case, the RF transmission line 20 has a length which extends between the first antenna 16 and the second antenna 18. Over that length, the RF transmission line 20 conforms with the shape of the board 2.

[0099] Mast assembly 4 is demountably secured to a lower surface of the housing 106 and a propulsion unit 8 is attached to the mast assembly 4. Antenna 25 (ref. Figure 7) is housed withinan upper member of the housing 106 of the wireless control unit 12 and is connected to the signal receiver and processing unit 26 of the wireless control unit 12 by means of an RF transmission line.

[0100] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that such prior art forms part of the common general knowledge.

[0101] It will be understood that the terms "comprise" and "include" and any of their derivatives (e.g. comprises, comprising, includes, including) as used in this specification, and the claims that follow, is to be taken to be inclusive of features to which the term refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.

[0102] In some cases, a single embodiment may, for succinctness and / or to assist in understanding the scope of the disclosure, combine multiple features. It is to be understood that in such a case, these multiple features may be provided separately (in separate embodiments), or in any other suitable combination. Alternatively, where separate features are described in separate embodiments, these separate features may be combined into a single embodiment unless otherwise stated or implied. This also applies to the claims which can be recombined in any combination. That is a claim may be amended to include a feature defined in any other claim. Further a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of: a, b, or c" is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

[0103] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application or applications described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and / or features described or depicted herein. It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope as set forth and defined by the following claims.

Claims

CLAIMS1. An antenna arrangement for a watercraft comprising: a first antenna configured to wirelessly communicate with a wireless user device, the first antenna for securement to a top-side of the watercraft; a second antenna configured to wirelessly communicate with a wireless control unit, the second antenna for securement to an underside of the watercraft to place the second antenna in juxtaposed relationship with a third antenna of a wireless control unit; and a radio frequency (RF) transmission line conductively coupling the first antenna and the second antenna.

2. An antenna arrangement according to claim 1, wherein the first antenna is configured to wirelessly communicate signals through air.

3. An antenna arrangement according to claim 1 or 2, wherein the first antenna comprises a passive antenna.

4. An antenna arrangement according to any one of claims 1 to 3, wherein the first antenna comprises a patch antenna.

5. An antenna arrangement according to claim 4, wherein the patch antenna comprises a modified rectangular patch antenna having comers which are shaped to reduce the diagonal dimensions of the rectangular patch antenna.

6. An antenna arrangement according to any one of claims 1 to 5, wherein the second antenna comprises a laminar structure configured for securement between the underside of the watercraft and the wireless control unit.

7. An antenna arrangement according to claim 6, wherein the laminar structure has a perimeter which is shaped to correspond with at least a section of the perimeter of an upper surface of a housing of the wireless control unit.

8. An antenna arrangement according to any one of claims 1 to 7, wherein the second antenna comprises a passive antenna.

9. An antenna arrangement according to any one of claims 1 to 8, wherein the second antenna comprises an elongate end-fed conductive strip fed by means of a coplanar waveguide.

10. An antenna arrangement according to any one of claims 1 to 9, wherein the second antenna is configured to re-transmit a wireless signal received by the first antenna and wherein the RF transmission line conducts the received wireless signal to the second antenna.

11. An antenna arrangement according to any one of claims 1 to 10, wherein the first antenna is configured to re-transmit a wireless signal received by the second antenna and wherein the RF transmission line conducts the received wireless signal to the first antenna.

12. An antenna arrangement according to claim 6, wherein the laminar structure has a first major surface for contacting the underside of the watercraft, and a second major surface for contacting a surface of the wireless control unit when in the juxtaposed relationship therewith such that the surface of the wireless control unit substantially overlies the second major surface, and wherein the first major surface and the second major surface are on opposite faces of the second antenna.

13. A watercraft including an antenna arrangement according to any one of claims 1 to 12, wherein the antenna arrangement is attached to the watercraft to provide a signal path which supports signal communication between a wireless user device and a wireless control unit attached to the underside of the watercraft.

14. A watercraft according to claim 13, wherein the watercraft is in the form of board, and wherein the second antenna is secured to the underside of the board by clamping the second antenna between the underside of the board and a housing of the wireless control unit.

15. A watercraft according to claim 13 or 14, wherein the wireless control unit is configured to control an electric motor in coupled communication with the wireless control unit depending on signals received by the antenna of the wireless control unit from the second antenna.

16. A watercraft according to claim 15, wherein the electric motor is attached to a mast element of a hydrofoil assembly, the mast element having a top section including a plate memberfor receiving fastening means for securing the plate member to the underside of the board, wherein securing the plate member to the underside of the watercraft clamps the second antenna and the wireless control unit between the plate member and the underside of the board to hold the second antenna in juxtaposed relationship with the wireless control unit.

17. A watercraft according to any one of claims 14 to 16, wherein the RF transmission line is attached to the board and extends from the second antenna to the first antenna in conformity with the shape of the board.

18. A propulsion control system for a watercraft, comprising: an antenna arrangement according to any one of claims 1 to 12; a wireless control unit comprising an antenna configured to wirelessly communicate with the second antenna of the antenna arrangement, the wireless control unit further comprising a motor controller for controlling an electric motor in coupled communication with the motor controller depending on communication signals communicated by the second antenna to the antenna; and means for securing the wireless control unit to the underside of the watercraft such that when so secured the second antenna is clamped between the wireless control unit and the underside of the watercraft to place the second antenna in juxtaposed relationship with the antenna of the wireless control unit.

19. A watercraft fitted with a propulsion control system according to claim 18.

20. A watercraft comprising: a board having a hull; a propulsion unit for propelling the board; an antenna arrangement comprising: a first antenna located on a top-side of the board; a second antenna located on an underside of the hull; a radio frequency transmission line conductively coupling the first antenna to the second antenna to conduct communication signals between the first antenna and the second antenna; and a wireless control unit located on the underside of the hull, the wireless control unit incorporating a third antenna configured for coupled communication with the second antenna, the wireless control unit configured to control the propulsion unit depending on one or morecommunication signals received by the first antenna and communicated to the second antenna; wherein the second antenna is located proximal to the third antenna to allow wireless communication therebetween.

21. A watercraft according to claim 20, wherein the second antenna is clamped between the wireless control unit and the underside of the board to secure the second antenna in at a least partial overlapping relationship with the third antenna.

22. A watercraft according to claim 21 further comprising a hydrofoil assembly having a mast element, wherein a top section of the mast element is secured to the underside of the hull using fasteners which pass through the wireless control unit and the second antenna to secure the second antenna in the at least partial overlapping relationship with the third antenna, and wherein the propulsion unit is attached to the mast element.

Images