Emergency rescue device with harmonic reflector circuit

Abstract

An emergency rescue tool having a harmonic reflector circuit including an antenna connected to a nonlinear circuit via a matching circuit, and a casing partially enclosing the harmonic reflector circuit, wherein the harmonic reflector circuit is configured to receive a signal at a receive frequency (fRX) and to transmit the received signal at a transmit frequency (fTX), the transmit frequency being a multiple of the receive frequency, wherein the receive frequency (fRX) is between a first frequency and a second frequency, the first frequency being at least 800 MHz, and the second frequency being at least 34 MHz greater than the first frequency, and the received signal is transmitted at the transmit frequency (fTX) with an output power (Pout) of at least 70% of a maximum available output power (Pmax).

Description

[Technical field]

[0001] The present invention relates to an emergency rescue tool having a radar reflector, and more particularly to an emergency rescue tool having a radar reflector for harmonic radar. [Background technology]

[0002] Emergency rescue equipment with harmonic radar has been used for a long time in search and rescue operations around the world. In a typical avalanche situation, a skier is lost in an avalanche and a rescue team arrives shortly after, the skier is equipped with an emergency rescue equipment with a reflector. The rescue team is equipped with a detector that transmits a signal at a certain transmission frequency. When the skier's reflector receives this signal, the reflector converts the frequency of the signal to a multiple of that frequency and transmits the converted signal back to the detector. That is, the detector transmits at a first frequency and receives at a multiple of the first frequency, and this information is then used to determine the skier's location.

[0003] However, tuning the reflector of an emergency rescue tool involves tuning the antenna to receive at a first frequency and transmit at a multiple of the first frequency. Conventional reflectors also use nonlinear elements such as resonating diodes, and the antenna must be matched to this element to provide sufficient power for frequency conversion and retransmission of the converted signal. An example of a harmonic reflector is described in U.S. Pat. No. 6,456,228 B1. This patent provides guidelines for matching the components of a harmonic reflector with a transmission line section.

[0004] Another example is disclosed in "Antenna Matching at Frequencies to Complex Load Impedance" by K. Rasilainen, J. Ilvonen and V. Viikari, IEEE Antennas and Wireless Propagation Letters, vol. 14, no., pp. 535-538, 2015. doi:10.1109 / LAWP.2014.2370760.

[0005] According to the prior art as disclosed above, those skilled in the art mainly focus on providing good efficiency in terms of reflected power at a single frequency.

[0006] When conventional reflectors are installed on emergency rescue equipment with different characteristics, compromises must be made to minimize the effect of the object on the reflector. Conventional reflectors are designed for the object's typical electromagnetic environment. Thus, conventional reflectors are designed to be mounted on objects with similar characteristics, such as ski boots or ski helmets.

[0007] According to the prior art, such as EP 1 035 418 B1, the antenna is encapsulated in a dielectric, which solves the problem when the reflector is mounted inside the ski boot or attached to the outside of the ski boot.

[0008] However, known solutions present challenges with respect to the detection of objects of widely differing sizes and characteristics due to electromagnetic interactions between the object and the reflector.

[0009] The present invention aims to solve this problem. Summary of the Invention

[0010] The above problems are solved by an emergency rescue tool having a harmonic radar reflector that reflects an incoming signal at a receive frequency at a transmit frequency that is a multiple of the receive frequency, where the harmonic radar reflector is designed for a wideband response.

[0011] Prior art harmonic reflectors provide a narrowband response. This is due to the fact that prior art harmonic reflectors are primarily tuned to minimize return loss at a particular receiving frequency, meaning that most of the energy arriving at the harmonic radar is transferred to the nonlinear element. Harmonic reflectors can be tuned for a narrowband response. This further implies that prior art harmonic reflectors are sensitive to electromagnetic interactions with the object to which they are attached.

[0012] Prior art harmonic reflectors are designed to maximize performance for a single, constant environment. If the reflector is placed in an environment with different characteristics, performance will degrade. This is primarily due to changes in electromagnetic properties resulting in different antenna impedances, resulting in poor matching between the reflector antenna and the nonlinear element.

[0013] The present invention provides an emergency rescue tool comprising a harmonic reflector circuit with an antenna connected to a nonlinear circuit through a matching circuit and a casing completely or partially surrounding the harmonic reflector circuit, the harmonic reflector circuit being configured to receive a signal at a receiving frequency (fRX) and to retransmit the received signal at a transmitting frequency (fTX), the transmitting frequency being a multiple of the receiving frequency, the receiving frequency (fRX) being between a first frequency and a second frequency, the first frequency being at least 800 MHz and the second frequency being at least 34 MHz higher than the first frequency, the received signal being transmitted at the transmitting frequency (fTX) with an output power (Pout) of at least 70% of the maximum output power (Pmax) available for a frequency within the transmitting frequency range from a multiple of the first frequency to the same multiple of the second frequency. The wideband behavior of the harmonic reflector circuit thus allows the detection of objects of widely different materials and sizes. Using the emergency rescue tool in an environment with altered electromagnetic properties may degrade performance. This degradation due to the change in electromagnetic properties results in different antenna impedances, resulting in poor impedance matching between the reflector antenna and the nonlinear element. For example, such changed electromagnetic properties may be due to, for example, enclosing the harmonic reflector circuit in a casing of different materials, having different materials between the harmonic reflector circuit and the signal transmitted by the rescue team, or due to different humidity. By utilizing a harmonic reflector circuit with a wideband behavior, the emergency rescue instrument may be detected in a wide span of environments where prior art instruments tuned to a specific reception frequency would be weak. For example, by utilizing a harmonic reflector circuit with a wideband behavior, the emergency rescue instrument may be more robust and functional in a greater variety of casings and conditions. This may increase the safety of the user.

[0014] According to one embodiment, the first frequency may be 860.5 MHz and the second frequency may be 909.5 MHz.

[0015] According to one aspect, the maximum available output power (Pmax) may be at least 0.1% of the incoming radiated power at the antenna.

[0016] According to one embodiment, the maximum available output power (Pmax) may be at least 0.01% of the incident radiated power at the antenna.

[0017] According to one embodiment, the maximum available output power (Pmax) may be at least 0.001% of the incident radiated power at the antenna.

[0018] According to one aspect, the maximum available output power (Pmax) may be at least 0.0001% of the incident radiated power at the antenna.

[0019] According to one embodiment, the transmission frequency fTX may be twice the reception frequency fRX.

[0020] According to one aspect, the harmonic reflector may include a substrate having a metal film.

[0021] According to one aspect, the harmonic reflector may comprise a flexible substrate having a metal film.

[0022] According to one aspect, the antenna and components of the matching circuit may be formed in a metal film.

[0023] According to one embodiment, the harmonic reflector may comprise a diode as the nonlinear element.

[0024] According to one embodiment, the casing may comprise a material having a dielectric constant in the range of 1.6 and 15.

[0025] According to one embodiment, the casing may comprise a material having a dielectric constant in the range of 1.6 and 4. This may be various plastic materials such as, for example, polyurethane foam, PVC, bakelite, polystyrene, polyvinyl, nylon, and / or rubber.

[0026] According to one embodiment, the casing may comprise a material having a dielectric constant in the range of 3.8 and 14.5, which may be various glass materials, such as, for example, silicate glass, fused silica, soda-lime-silica glass, sodium borosilicate glass, lead oxide glass, aluminosilicate glass, and / or germanium oxide glass.

[0027] According to one embodiment, the casing may comprise a material having a dielectric constant in the range of 80 and 81. This may be, for example, water in various states and with various additives.

[0028] According to one embodiment, the casing may comprise a material having a dielectric constant in the range of 1 and 1.0006. This may be, for example, a vacuum or air at various states or pressures and with various additives.

[0029] According to one aspect, the casing may comprise a material that shifts the operating frequency range of the harmonic reflector circuit.

[0030] According to one embodiment, the operating frequency range of the harmonic reflector may be between a first frequency and a second frequency.

[0031] According to one embodiment, the operating frequency range of the harmonic reflector may be a span of frequencies between a first frequency and a second frequency.

[0032] According to one aspect, the operating frequency range may be shifted by at least partially covering the emergency rescue device in a liquid.

[0033] According to one aspect, the casing may have a first state and a second state, the operating frequency range being shifted in the second state compared to the first state.

[0034] According to one aspect, the casing may comprise a material having a first dielectric constant in a first state and a second dielectric constant in a second state, and the operating frequency range is shifted in the second state compared to the first state, the first state being dry and the second state being wet.

[0035] According to one embodiment, the casing may be made of leather. For example, the casing may be or be part of an article of wear, clothing, or tag. For example, the casing may be a belt, boot, shoe, bracelet, other article of wear, pendant, or the like.

[0036] According to one embodiment, the casing may be made of fabric, for example, the casing may be or be part of a garment, clothing, or tag, such as a jacket, ski jacket, wind jacket, pants, backpack, or the like.

[0037] According to one aspect, the casing may be made of plastic. For example, the casing may be or be part of a garment, article of clothing, or a tag.

[0038] According to one embodiment, the casing may be a shoe. The harmonic reflector may be mounted, for example, on the exterior of the shoe or within an internal compartment. The harmonic reflector circuit may be solid cast as part of the shoe. The shoe may be, for example, a boot, a hiking shoe, a ski boot, and / or a regular shoe.

[0039] According to one aspect, the casing may be a life jacket. The harmonic reflector circuit may be mounted, for example, on the exterior of the life jacket or within an internal compartment. The harmonic reflector circuit may be solid, cast as part of the life jacket. The life jacket may be inflatable or solid.

[0040] According to one embodiment, the casing may be a bracelet. The harmonic reflector circuit may be mounted, for example, on the exterior of the bracelet or in an internal compartment.

[0041] Further features and advantages of the present invention are presented in the following detailed description of exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings. [Brief description of the drawings]

[0042] The above will be apparent from the following more particular description of exemplary embodiments, as illustrated in the accompanying drawings, in which like reference characters refer to the same parts throughout the various views, and in which the drawings are not necessarily to scale, emphasis instead being placed upon illustrating exemplary embodiments.

[0043] [Figure 1] FIG. 2 is a schematic diagram of a detector and harmonic reflector circuit. [Diagram 2] 1 is a graph showing reflected power from a prior art harmonic reflector. [Diagram 3] FIG. 1 is a schematic diagram of a prior art harmonic reflector circuit interacting with an object to which it is attached. [Figure 4] FIG. 2 is a schematic diagram of a harmonic reflector circuit and a detector according to one embodiment of the present invention. [Diagram 5] 4 is a graph illustrating the response provided by a harmonic reflector according to one embodiment of the present invention. [Figure 6] 1 is an embodiment of a harmonic reflector circuit in accordance with an embodiment of the present invention. [Figure 7] 1 is an embodiment of an emergency rescue device having a harmonic reflector circuit according to an embodiment of the present invention. [Figure 8] 1 is an embodiment of an emergency rescue device having a harmonic reflector circuit according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] FIG. 1 shows a harmonic reflector circuit, generally designated 101, and a detector, generally designated 102.

[0045] The detector 102 transmits a signal S1 of frequency fRX. This signal S1 is received by the harmonic reflector circuit 101, which converts it and transmits it as a second signal S2 of frequency fTX. The harmonic reflector circuit 101 receives the incoming signal S1 by means of an antenna 103. The antenna 103 is connected to a matching circuit 104 which provides impedance matching between the antenna 103 and the nonlinear circuit 105 for both the frequency fRx and the frequency fTX. The impedance matching is essential for a low-loss conversion of the first signal S1 to a second signal S2, respectively of frequencies fRX and fTX.

[0046] 2 discloses a typical response from the harmonic reflector 102. A first curve 201 shows the reflected power P from a transmitted signal at frequency fc, the bandwidth of the curve 201 depending on the impedance match between the nonlinear circuit 105 and the antenna 103, and of course also on the bandwidth of the antenna 103 and the nonlinear circuit 105 themselves.

[0047] In FIG. 3, the harmonic reflector circuit 101 is shown with a ground plane 301. The ground plane 301 may be a physical object, such as a helmet or a human being. The ground plane 301 causes an inductive coupling to the harmonic reflector circuit 101 that changes the characteristics of the matching circuit 104. This means that the reflected power at frequency fc decreases from P to P' on the corresponding curve 202. In the prior art harmonic reflector circuit 101, the matching circuit is configured to provide a match to a given ground plane at a given distance and in a given dielectric environment. For example, the harmonic reflector 101 is sized for mounting to a ski boot or a helmet, i.e., a ground plane of the same order of magnitude and similar dielectric properties. That is, a conventional harmonic reflector circuit 101 mounted on one pair of glasses or mounted on a container would provide a very different response in terms of reflected power P, due in part to the large differences in the dielectric properties of the ground plane and the surroundings.

[0048] The inventors of the present invention have realized that the issue of varying ground plane characteristics and dielectric properties is a major factor contributing to the challenge of detecting harmonic radar returns from objects of varying characteristics.

[0049] The inventors of the present invention have realized that a solution to the above problem of harmonic radar reflection from objects with varying characteristics is provided by increasing the bandwidth of the harmonic reflector circuit 101. This can be seen by examining FIG. 4, in which the reflected harmonic power P is shown as a function of frequency f. A first curve 401 shows the reflected harmonic power centered on a center frequency fc, which first curve provides a larger bandwidth compared to the prior art curve 201. Assume that the ground plane 301 is placed such that coupling from the ground plane to the harmonic reflector circuit 101 causes a shift from the first curve 401 to a second curve 402 having a center frequency fc'. The y-axis of FIG. 4 discloses the reflected power at a frequency fTX, which is a multiple of the frequency fRX. The x-axis shows the received frequency fRX. The reflected power P decreases to P', but this is much less than the decrease shown in FIG. 2. This means that the reflected power P is not significantly affected by the ground plane 301.

[0050] In Fig. 5, the reflected power P at the transmission frequency fTX is shown as a function of the reception frequency fRX from the harmonic reflector circuit 101 according to the invention. The reception frequency (fRX) is between a first frequency f1 and a second frequency f2, the first frequency f1 being at least 800 MHz. The second frequency f2 is at least 34 MHz greater than the first frequency. The received signal is transmitted at the transmission frequency (fTX) with an output power (Pout) of at least 70% of the maximum output power (Pmax) available for the defined electromagnetic environment.

[0051] In one embodiment, the first frequency is 860.5 MHz and the second frequency is 909.5 MHz.

[0052] In Figure 6, one embodiment of a harmonic reflector circuit, generally designated 601, is depicted in top view and to scale. The harmonic reflector circuit 601 comprises a nonlinear circuit, which in this embodiment is a surface-type diode 602 soldered to a metal film 603 of a substrate. The antenna and matching circuit are integrally formed in the metal film 603 of the substrate. The harmonic reflector circuit 601 is drawn to scale; that is, by measuring and scaling the diagram, a wideband harmonic reflector circuit 601 is realized.

[0053] In Fig. 7, an embodiment of an emergency rescue tool with a harmonic reflector circuit is shown. In the illustrated embodiment, the emergency rescue tool 700 has two harmonic reflector circuits 701 and 702 enclosed by a hiking boot shaped casing 703. The emergency rescue tool 700 may alternatively have a single harmonic reflector circuit or multiple harmonic reflector units. The harmonic reflector units may be located, for example, in the tongue of the hiking boot as harmonic reflector unit 701 and / or in the quarter of the hiking boot as harmonic reflector unit 702. The harmonic reflector units may be located in other parts of the hiking boot or shoe, such as the lining, backstay, heel, sole, vamp, toe box, counter, and / or the like.

[0054] One embodiment of an emergency rescue device having a harmonic reflector circuit is shown in Figure 8. In the illustrated embodiment, the emergency rescue device 800 has a harmonic reflector circuit 801 surrounded by a casing 803 in the shape of a life jacket.

Claims

1. An emergency rescue device having a harmonic reflector circuit, an antenna connected to a nonlinear circuit via a matching circuit; and a casing that completely or partially surrounds the harmonic reflector circuit; the harmonic reflector circuit is configured to receive a signal at a receive frequency and to retransmit the received signal at a transmit frequency; the transmit frequency is a multiple of the receive frequency; The harmonic reflector circuit comprises: the receiving frequency is between a first frequency and a second frequency; the first frequency is at least 800 MHz; the second frequency is at least 34 MHz higher than the first frequency; The received signal is retransmitted on the transmission frequency at an output power of at least 70% of the maximum available output power.

2. the first frequency is 860.5 MHz; The emergency rescue instrument according to claim 1 , wherein the second frequency is 909.5 MHz.

3. 3. The emergency rescue instrument according to claim 1 or 2, wherein the maximum available output power is at least 0.1% of the incident radiated power at the antenna.

4. 4. The emergency rescue instrument according to claim 1, wherein the transmission frequency is twice the reception frequency.

5. 5. An emergency rescue tool according to any one of claims 1 to 4, comprising a substrate having a metal film.

6. 6. The emergency rescue tool according to claim 5, wherein the antenna and components of the matching circuit are formed on the metal film.

7. The emergency rescue tool according to claim 4 or 5, further comprising a diode as the nonlinear circuit.

8. 8. An emergency rescue tool according to any one of claims 1 to 7, wherein the casing comprises a material having a dielectric constant in the range of 1.6 and 15.

9. 9. An emergency rescue tool according to any one of claims 1 to 8, wherein the casing comprises a material that shifts the operating frequency range of the harmonic reflector circuit.

10. The emergency rescue tool according to claim 9, wherein the operating frequency range is shifted by at least partially covering the emergency rescue tool in a liquid.

11. the casing has a first state and a second state; 10. The emergency rescue instrument according to claim 9, wherein the operating frequency range is shifted in the second state compared to the first state.

12. the casing comprises a material having a first dielectric constant in a first state and a second dielectric constant in a second state; the operating frequency range is shifted in the second state compared to the first state; 10. The emergency rescue tool of claim 9, wherein the first condition is dry and the second condition is wet.

13. An emergency rescue tool according to any one of claims 1 to 12, wherein said casing is made of leather.

14. An emergency rescue tool according to any one of claims 1 to 12, wherein the casing is made of fabric.

15. An emergency rescue tool according to any one of claims 1 to 12, wherein the casing is made of plastic.

16. 16. Emergency rescue tool according to any one of claims 1 to 15, wherein the casing is a shoe.

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