Antenna Polarization

Abstract

According to the present invention, there is provided a polarization converter comprising a first element array layer extending in a plane comprising a first array of spaced apart conductive dipole elements, a second element array layer extending in the plane comprising a second array of spaced apart conductive dipole elements, and a dielectric layer extending in the plane separating the first and second element array layers, each element array layer having first and second axes parallel to the plane of the respective element array layer, the first and second axes being perpendicular axes, and one or both of the element array layers exhibiting anisotropic spatial properties. Antenna systems, vehicles, and methods of manufacturing the polarization converter are also provided.

Description

[Technical Field]

[0001] The present disclosure relates to a polarization converter. The present disclosure also relates to an antenna system for a communication device. The present disclosure also relates to a vehicle having the antenna system. The present disclosure also relates to a method of manufacturing a polarization converter. [Background technology]

[0002] Linear-to-circular polarization converters for converting linearly polarized electromagnetic (EM) radiation into circularly polarized EM radiation are known in the art.

[0003] An example of a conventional transducer comprises a dipole array printed on a grounded dielectric layer. A linearly polarized EM wave incident on the transducer can be converted into a circularly polarized reflected EM wave.

[0004] However, conventional transducers have poor angular stability. That is, the relationship between the axial ratio of the reflected wave (which provides a measure of how circularly polarized the wave is) and the frequency of the EM radiation varies significantly depending on the angle of incidence of the incident linearly polarized radiation. As a result, certain frequencies of EM radiation that are adequately converted to circular polarization at one angle of incidence are poorly converted at another angle of incidence. This is problematic because maintaining a consistent angular relationship between the incident radiation and the transducer is necessary to produce a sufficient circularly polarized output. This is difficult to achieve in practice and can limit the widespread application of such transducers.

[0005] It is an object of the present invention to provide an improved system and / or method and / or to address one or more of the problems set forth above or elsewhere, or to at least provide an alternative system and / or method. Summary of the Invention

[0006] According to a first aspect of the present invention, there is provided a polarization converter comprising: a first element array layer extending in a plane comprising a first array of spaced-apart conductive dipole elements; a second element array layer extending in the plane comprising a second array of spaced-apart conductive dipole elements; and a dielectric layer extending in the plane separating the first and second element array layers, each element array layer having first and second axes parallel to the plane of the respective element array layer, the first axis and the second axis being vertical axes, and one or both of the element array layers exhibiting anisotropic spatial properties. The polarization converter may be a linear-to-circular polarization converter.

[0007] In this way, a device having a double-layer dipole array structure is formed, capable of converting a linearly polarized incident wave into a circularly polarized reflected wave. Such a converter has applications in converting linearly polarized radiation from readily available, low-cost linear antennas into circularly polarized radiation for use in satellite, communication, and sensing systems.

[0008] In one example, one or both of the arrays of dipole elements exhibit anisotropic spatial properties. In one example, the spacing between dipole elements of the arrays varies along the first axis and the second axis. In one example, the periodicity of the arrays of dipole elements varies along the first axis and the second axis.

[0009] In this way, linear-to-circular polarization conversion is facilitated. "Anisotropic spatial properties" may mean that the spatial properties differ between the first axis and the second axis in one or both of the element array layers. The anisotropy can be achieved by the periodicity of the element array layers and / or the spacing of the dipole elements.

[0010] In one example, one or both of the arrays of dipole elements have a first periodicity measured along a first axis and a second periodicity measured along a second axis, the second periodicity being different from the first periodicity.

[0011] In this way, a polarization converter with a double periodic anisotropic array structure is formed, which facilitates linear-to-circular polarization of the incident EM wave.

[0012] In one example, the first and second element array layers have the same first and second periodicities. That is, although the first and second periodicities may be different, the first element array layer may have an array of dipoles with dipoles spaced according to the first periodicity along a first axis and spaced according to the second periodicity along a second axis, and the second element array layer may have the same arrangement. The first and second element array layers may have the same dimensions (i.e., overall length and width).

[0013] Advantageously, this tends to lead to a structure in which the dipole elements in the first element array layer have high element coupling, which improves angular stability. Furthermore, in constructing a transducer, array layers with the same periodicity simplify construction. That is, the array layer can be formed from array layer sheets, or the array layer can be constructed from constituent unit cells that, when assembled, form an element array layer with the same first and second periodicities.

[0014] In one example, the dipole elements of the second element array layer are each laterally displaced relative to the dipole elements of the first element array layer.

[0015] In this way, a polarization converter with an anisotropic array structure is formed, which facilitates linear-to-circular polarization of the incident EM wave.

[0016] In one example, the dipole elements of the second element array layer are each laterally displaced along a first axis relative to the dipole elements of the first element array layer.

[0017] In this way, a polarization converter with an anisotropic array structure is formed, facilitating linear-to-circular polarization of the incident EM wave. Nevertheless, this leads to a structure in which there is some overlap between the dipole elements of the element array layer, which tends to provide high element coupling and advantageous improvements in angular stability.

[0018] In one example, the dipole elements of the second element array layer are each positioned in laterally aligned relation to the dipole elements of the first element array layer along the second axis.

[0019] In this way, there is overlap between the dipole elements of the element array layer, which tends to provide high element coupling and advantageously improved angular stability. Some deviation from precise lateral alignment is possible without loss of angular stability. Nevertheless, this offset is not large enough to produce overlap along the second axis, as will be understood from the description herein.

[0020] In one example, the plurality of dipole elements of the first element array layer and / or the second element array layer exhibit anisotropic spatial properties.

[0021] Anisotropy can also be achieved by the shape or configuration of the dipole elements. In this way, a polarization converter with an anisotropic array structure is formed. This facilitates linear-to-circular polarization of the incident EM wave.

[0022] In one example, each dipole element has a first dimension measured along a first axis and a second dimension measured along a second axis, the first and second dimensions being different.

[0023] This can define anisotropic spatial properties. The dipole elements can be of any shape, but having different first and second dimensions provides anisotropy, which facilitates operation as a linear-to-circular polarization converter.

[0024] In one example, in a plan view, a region of one of the dipole elements of the first element array layer overlaps with one or more regions of the dipole elements of the second element array layer. In one example, in a plan view, a region of one of the dipole elements of the first element array layer overlaps with one or more regions of the dipole elements of the second element array layer along a first axis.

[0025] This provides a structure in which there is some overlap between the dipole elements of the element array layer, which tends to provide high element coupling and advantageously improved angular stability. High element coupling results in an increase in the effective electrical length of the elements, which leads to a decrease in the array resonant frequency, thereby improving the angular stability of the polarization converter. Overlap along the first axis tends to favor high element coupling. In some instances, there is no overlap along the second axis.

[0026] In one example, an end region of one of the dipole elements of a first element array layer overlaps with an end region of two of the dipole elements of a second element array layer. Such a structure has been found to be particularly advantageous. The overlap can be provided by a structure having two element array layers, one of which is appropriately shifted in plan view to provide the described overlap.

[0027] In one example, in plan view, 1 to 50% of the length of one of the dipole elements of the first element array layer overlaps with one or more regions of the dipole elements of the second element array layer. In a preferred example, 20 to 30% of the length of one of the dipole elements of the first element array layer overlaps with one or more regions of the dipole elements of the second element array layer. In a highly preferred example, approximately 26% of the length of one of the dipole elements of the first element array layer overlaps with one or more regions of the dipole elements of the second element array layer. The overlap in length can be an overlap in area, if appropriate (i.e., there can be an overlap of 1 to 50%, 20 to 30%, or 26% of area rather than length).

[0028] It will be understood by those skilled in the art that, depending on how the first and second element array layers are arranged, the length or area of overlap in plan view between one of the dipole elements of the first element array layer and one or more dipole elements of the second element array layer may be the same as the length or area of overlap in plan view between one of the dipole elements of the second element array layer and one or more dipole elements of the first element array layer.

[0029] In one example, each dipole element has a rectangular cross-sectional profile, eg, a solid rectangle or rectangular loop, or an oval cross-sectional profile, eg, a solid oval or oval loop.

[0030] This exemplary dipole element geometry has been found to be particularly advantageous, as it provides a polarization converter with an anisotropic array structure, facilitating linear-to-circular polarization of the incident EM wave.

[0031] The polarization converter may include a ground plane, and the first element array layer, the dielectric layer, and the second element array layer are disposed on the ground plane. In one example, the ground plane is a grounded metal substrate. In one example, the ground plane or grounded metal substrate is mounted on or forms part of the polarization converter or an antenna system including the polarization converter. This provides a versatile, self-contained polarization converter. In another example, the ground plane or grounded metal substrate is mounted on or forms part of a vehicle to which the polarization converter is attached. In other words, when the polarization converter is attached to a vehicle, the polarization converter may use a portion of the vehicle as a ground plane. In this way, a body panel of such a vehicle, such as an aircraft panel or a ship hull, can be used and function with the device to convert EM waves from linear polarization to circular polarization. Advantageously, this arrangement tends to eliminate the need for a conventional exposed antenna on the vehicle; i.e., the antenna does not extend outward with the vehicle's existing contours, which avoids drag or low observability penalties, for example, reducing the vehicle's radar cross section. In this example, the ground plane is a grounded metal substrate, but this is considered non-limiting and other ground planes such as metal alloys, semi-metals, metal matrix composites, or any other conductive surface may be used.

[0032] According to a second aspect of the present invention, there is provided an antenna system for a communication device, the antenna system comprising an antenna arranged to generate polarized electromagnetic radiation and a polarization converter according to the first aspect. The antenna may be arranged to generate linearly polarized electromagnetic radiation. The antenna system may form part of a satellite communication receiver, such as a GPS, GLONASS, or Galileo receiver. In other words, the antenna system may form part of a navigation system. The antenna system may form part of a telecommunications transceiver, such as a broadband telecommunications transceiver including 4G and 5G. The antenna system may form part of a tactical data link receiver, such as a Link 16 or Link 22 receiver.

[0033] In this manner, linearly polarized radiation can be generated by an antenna and converted to circularly polarized radiation. Antennas arranged to generate linearly polarized EM radiation are readily available and low cost, especially compared to antennas arranged to generate circularly polarized radiation. Facilitating the generation of circularly polarized radiation in this manner therefore tends to be highly advantageous.

[0034] According to a third aspect of the present invention, there is provided a vehicle including the antenna system according to the second aspect. The vehicle may be an aircraft, such as a manned or unmanned aircraft. The antenna system may provide a means for the aircraft to receive communication signals from a base station. Alternatively, the antenna system may provide a means for the aircraft to receive navigation data from a satellite navigation system. In other words, the vehicle may include a navigation system or a communication system including the antenna system.

[0035] In this way, advantages in communication and sensing can be realized.

[0036] According to a fourth aspect of the present invention, there is provided a method of converting linearly polarised radiation into circularly polarised radiation, the method comprising providing a polarisation converter, a communications device or a vehicle according to the first, second or third aspect respectively; disposing a first element array layer, a dielectric layer and a second element array layer above a ground plane; and irradiating the device with linearly polarised radiation, wherein reflected radiation is circularly polarised.

[0037] In one example, the method comprises reflecting linearly polarized radiation from a polarization converter, an antenna system, or a vehicle, thereby generating or transmitting circularly polarized radiation. In one example, the method comprises mounting the polarization converter or antenna system on the vehicle.

[0038] According to a fifth aspect of the present invention, there is provided a method for manufacturing a polarization converter, the method comprising the steps of: providing a first element array layer extending in a plane and a second element array layer extending in a plane, each element array layer having first and second axes parallel to the plane of the respective element array layer, the first axis and the second axis being perpendicular axes, and one or both of the element array layers exhibiting anisotropic spatial properties; and laminating the first element array layer comprising a first array of spaced-apart conductive dipole elements, the second element array layer comprising a second array of spaced-apart conductive dipole elements, and a dielectric layer extending in the plane separating the first element array layer and the second element array layer.

[0039] Features of any of the above aspects may be combined as desired or required. [Brief explanation of the drawings]

[0040] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic perspective view of a prior art linear-to-circular polarization converter. [Figure 2] FIG. 2 shows a graph of the axial ratio of reflected radiation versus frequency at different angles of incidence for the prior art transducer of FIG. [Figure 3] FIG. 3 shows a schematic side view of a polarization converter according to an embodiment. [Figure 4a-4b] 4(a) and (b) show schematic plan views of the first and second element array layers of the transducer of FIG. 3 in isolation. [Figure 5] FIG. 5 shows a schematic exploded perspective view of a portion of the transducer of FIG. [Figure 6a-6b] 6(a) and (b) show the geometric configuration of the TM and TE incident on a portion of the transducer of FIG. [Figure 7a-7b] Figures 7(a) and (b) show graphs of the reflected phase of the TE and TM components. [Figure 8a-8b]8(a) and (b) show graphs of the axial ratio of the reflected radiation versus frequency at different angles of incidence. [Figure 9] FIG. 9 shows an antenna system for a communication device. [Figure 10] FIG. 10 shows a vehicle according to an embodiment. [Figure 11] Figure 11 illustrates the general methodological principle. [Figure 12] FIG. 12 illustrates the general methodological principle. Detailed Description

[0041] Referring to Figure 1, there is shown a prior art linear to circular polarization converter 1. The polarization converter 1 comprises an arrangement of dipole elements 2 arranged in a single layer and printed on a grounded dielectric slab 4.

[0042] The propagation direction of the incident EM wave (which may be referred to as the "angle of incidence") is indicated by the angle θ measured from an axis perpendicular to the plane of the layers of dipole element 2 (the z-axis).

[0043] Referring to Figure 2, a graphical representation of the axial ratio of reflected radiation versus frequency at different angles of incidence for Transducer 1 is shown. The term "angular stability" is used to refer to the amount of variation in the relationship between axial ratio and frequency for different angles of incidence of the incident EM wave. As shown in the figure, Transducer 1 has a large change in the axial ratio of reflected radiation at frequencies above about 10 GHz as the angle of incidence varies from θ=0 to θ=30 to θ=45. That is, Transducer 1 has poor angular stability at frequencies above about 10 GHz.

[0044] Referring to FIG. 3 , a polarization converter 100 according to an embodiment is shown. More specifically, the polarization converter is for converting linearly polarized incident EM radiation to circularly polarized radiation. In another embodiment, the polarization converter may be modified to convert circularly polarized incident radiation to linearly polarized radiation. The converter 100 comprises a first element array layer 120, a second element array layer 140, and a dielectric layer 160. The converter 100 further comprises a Taconic RF35 substrate 180. The converter 100 further comprises a ground plane in the form of a grounded metal substrate 190. The first element array layer 120, the second element array layer 140, and the dielectric layer 160 are disposed on the grounded metal substrate 190. In this exemplary embodiment, the incident EM wave is reflected from the grounded metal substrate 190 and converted from linearly polarized to circularly polarized through interaction with the first element array layer 120 and the second element array layer 140. In this example, the grounded metal substrate 190 forms part of the transducer 100, however, those skilled in the art will appreciate that the substrate 190 may be provided separately and may form part of the structure to which the transducer 100 is mounted, for example, as part of a ground vehicle, watercraft, or aircraft.

[0045] The first element array layer 120 extends in a plane referred to as the "first plane," which in this exemplary embodiment is a horizontal plane. The first element array layer 120 comprises a first array of spaced apart conductive dipole elements 122.

[0046] The second element array layer 140 extends in a plane referred to as the "second plane," which in this exemplary embodiment is a horizontal plane. The second element array layer 140 comprises a second array of spaced apart conductive dipole elements 142.

[0047] The dielectric layer 160 extends in a plane referred to as the "third plane," which in this exemplary embodiment is a horizontal plane. The dielectric layer 160 separates the first element array layer 120 and the second element array layer 140. That is, the dielectric layer 160 electrically insulates the first element array layer 120 and the second element array layer 140. The dielectric layer 160 is formed of polyimide.

[0048] The dipole elements are formed on opposite sides of the dielectric layer 160. In this exemplary embodiment, a second array of dipole elements 142 is formed above the substrate 180 and below the dielectric layer 160. A first array of dipole elements 122 is formed on the dielectric layer 160. The dipole elements 122, 142 are formed of copper. The first element array layer 120, the second element array layer 140, and the dielectric layer 160 are substantially parallel.

[0049] 4(a) and 4(b), element array layers 120, 140 are shown in isolation and in plan view. As shown, each element array layer 120, 140 has first and second axes parallel to the plane of the respective element array layer, the first and second axes being perpendicular axes.

[0050] One or both of the element array layers 120, 140 exhibit anisotropic spatial properties. In this way, linear-to-circular polarization conversion is facilitated, and the anisotropic design imposes a differential phase shift on the two polarizations (TM and TE) of an incident plane wave. "Anisotropic spatial properties" means that the spatial properties are different between a first axis and a second axis in one or both of the element array layers 120, 140. The anisotropy can be achieved by the periodicity of the element array layers 120, 140, the spacing of the dipole elements 122, 142, and / or the shape or form of the dipole elements 122, 142.

[0051] The first and second axes are illustrated in the figures as the "y" and "x" axes. As shown, both arrays of dipole elements 122, 142 exhibit anisotropic spatial properties. That is, in the illustrated embodiment, the spacing between dipole elements 122, 142 is different in the first axis and the second axis. As such, elements in the first element array layer 120 and elements in the second element array layer 140 overlap in either axis.

[0052] Additionally, the periodicity of the array of dipole elements differs between the first and second axes. Thus, there are more dipoles per unit length along the second axis (the "x" axis) compared to the first axis (the "y" axis). Here, both of the arrays of dipole elements have a first periodicity measured along the first axis and a second periodicity measured along the second axis, where the second periodicity is different from the first periodicity. The first element array layer 120 and the second element array layer 140 have the same first and second periodicities.

[0053] As can be seen from Figures 4(a) and 4(b), in the assembled transducer 100, the dipole elements 142 of the second element array layer 140 are laterally displaced relative to the dipole elements 122 of the first element array layer 120. This can be described as the arrays being "shifted" relative to each other. Such an arrangement is anisotropic.

[0054] Furthermore, in the assembled transducer 100, the dipole elements 142 of the second element array layer 140 are each laterally aligned along the second axis relative to the dipole elements 122 of the first element array layer 120. This facilitates element coupling, which will be described in more detail below.

[0055] As discussed above, anisotropy can also be achieved by the shape or configuration of the dipole elements. In this exemplary embodiment, the dipole elements 122, 142 of the first element array layer 120 and the second element array layer 140 exhibit anisotropic spatial properties. As shown, each dipole element has a first dimension measured along a first axis and a second dimension measured along a second axis. The first and second dimensions are different. In this illustrated embodiment, each dipole element 122, 142 has a rectangular shape with a solid structure. Those skilled in the art will understand that other shapes of dipole elements are suitable, having different first and second dimensions, such as, for example, a rectangular loop, an oval shape with a solid structure, and / or an oval loop.

[0056] As can be seen from the plan views of the element array layers 120, 140 shown in FIGS. 4(a) and 4(b), and also from the portion of the transducer 100 illustrated in FIG. 5, which is shown with a transparent dielectric layer 160, in the plan view, a region of one of the dipole elements 122 of the first element array layer 120 overlaps with one or more regions of the dipole elements 142 of the second element array layer 140. In this embodiment, in the plan view, one of the dipole elements 122 of the first element array layer 120 overlaps with two end regions of the dipole elements 142 of the second element array layer 140. This overlap provides strong capacitive coupling of the elements between the layers 120, 140. This results in improved angular stability of the transducer 100, which will be described in further detail below. In this exemplary embodiment, there is a total overlap (i.e., including both overlapping ends) of approximately 26% of the length of the dipole elements.

[0057] Dimensions of the transducer 100 according to an exemplary embodiment are provided with reference to FIGS. 3, 4(a), 4(b), and 5. FIG. In the exemplary embodiment described herein, to which the graphs of Figures 7 and 8 relate, the transducer 100 has the following dimensions: A (height of layers 120, 140, 160) = 0.12 mm, B (height of substrate 180) = 1.524 mm, L (length of dipole element) = 2.15 mm, W (width of dipole element) = 0.5 mm, Dx (width of "unit cell" of element array layers 120, 140) = 1 mm, Dy (length of "unit cell" of element array layers 120, 140) = 3.75 mm, Dy / 2 (shift along the y-axis of dipole elements 142 of the second element array layer 140 relative to dipole elements 122 of the first element array layer when viewed in plan view) = 1.875 mm, overlap of dipole element lengths at one end region = 0.275 mm.

[0058] The dimensions of the exemplary embodiment are provided without limitation or loss of generality to the structure of the converter 100. Those skilled in the art will understand that variations in dimensions are possible while still functioning as a linear to circular polarization converter.

[0059] Referring to Figures 6(a) and 6(b), the geometry of an incident EM wave with a transducer 100 is shown, with only a portion of the transducer 100 shown. The propagation direction of the linearly polarized incident EM wave (which may be referred to as the "angle of incidence") is indicated by the angle θ measured from an axis perpendicular to the plane of the element array layers 120, 140 and the dielectric layer 160. Figures 6(a) and 6(b) show the TM and TE components of the linearly polarized incident wave, respectively, with equal magnitude and phase when θ = 0. In this case, the E field is at an angle of 45° or 135° with respect to the y-axis. The incident wave has an electric field component E, a magnetic field component H, and a wave vector k.

[0060] Referring to Figures 7(a) and 7(b), graphs of the reflected phase versus frequency of the TE (solid line) and TM (dashed line) components are shown. Figures 7(a) and 7(b) illustrate the reflected phase versus frequency in two mutually orthogonal planes of incidence, with Figure 7(a) showing the xz plane or Φ = 0° and Figure 7(b) showing the yz plane or Φ = 90°. For the converter 100 to convert a linearly polarized incident wave into a circularly polarized reflected wave, the converter 100 must generate a phase difference with respect to the incident wave that is an odd multiple of 90°. Figures 7(a) and 7(b) show the reflected phase when the linearly polarized wave is incident at an angle θ = 45° with respect to the y-axis. As can be determined from the graphs, linear-circular polarization is achieved at various frequencies where the reflected phase is equal to 270°.

[0061] 8(a) and 8(b), there are shown graphical representations of the axial ratio versus frequency of reflected radiation at different angles of incidence for the transducer 100. As mentioned above, the term "angular stability" is used to refer to the amount of variation in the relationship between axial ratio and frequency for different angles of incidence of the incident EM wave.

[0062] 8(a) and 8(b) illustrate the axial ratio versus frequency in two mutually orthogonal planes of incidence, with FIG. 8(a) showing the xz plane or Φ=0° and FIG. 8(b) showing the yz plane or Φ=90°. As can be established from the figures, the transducer 100 reduces the change in the axial ratio of the reflected radiation at frequencies above 10 GHz as the angle of incidence similarly varies from θ=0 (solid line) to θ=30 (dotted line) to θ=45 (dashed line), compared to the graph of FIG. 2 for the conventional transducer 1. That is, the transducer 100 has improved angular stability at frequencies above about 10 GHz.

[0063] The high element coupling due to the above-described element array layer and dipole element arrangement results in the improved angular stability demonstrated herein. Element coupling provides an increase in effective element, which results in a change in the array resonant frequency. From the figures, it can be seen that the circular polarization performance in terms of axial ratio, angular stability, and 3-dB-axial ratio bandwidth is satisfactory for the frequency range of 8.2 to 18.3 GHz for both TE and TM in the X-band and KU-band. This frequency range can be achieved using a transducer 100 having the dimensions described above (i.e., dipole element dimensions, layer height, etc.).

[0064] Those skilled in the art will understand that other dimensions are possible while still maintaining angular stability, but that the frequency range may differ if the dimensions of the transducer are changed. For example, a larger (or longer) dipole couples to an incident field with a longer wavelength, which has the effect of shifting the frequency range to lower frequencies. Furthermore, increasing the overlap of the dipoles has the effect of increasing the capacitive coupling of the elements between layers 120 and 140, which in turn shifts the frequency range to lower frequencies. The choice of substrate 180 also affects the operating frequency range. A substrate material with a high dielectric constant has the effect of reducing the effective wavelength of the incident field. This means that the dipole appears "electrically longer," and therefore the operating frequency range of the transducer 100 is shifted lower.

[0065] Those skilled in the art will appreciate that the structure of the transducer 100 tends to reduce the effects of grating lobes, which are an undesirable feature in antenna design. The design of the transducer 100, particularly the shift in resonant frequency due to high element coupling, pushes the grating lobes to higher frequencies, providing the benefit of angular stability. Sensitivity to the angle of incidence of incident EM radiation thereby tends to be reduced.

[0066] Referring to FIG. 9, an antenna system 1000 is shown. The antenna system 1000 includes an antenna 1100 arranged to generate linearly polarized EM radiation. Such antennas are well known in the art and may include whip antennas, stripline antennas, monopole antennas, dipole antennas, and patch antennas. The antenna system 1000 may form part of a communication device for providing a communication link with another communication device, the link operating in the 698-3600 MHz spectrum region according to standards such as GSM, CDMA, LTE, WiMax, and future 5G standards. The antenna system 1000 may be coupled to a transceiver, a transmitter or receiver, a power source, and other standard components to enable the communication link. The receiver may be a satellite navigation receiver, such as for receiving navigation data from the GPS, GLONASS, or Galileo systems. In other words, the antenna system 1000 may form part of a navigation system.

[0067] The antenna system 1000 further comprises a polarization converter 100 according to an embodiment.

[0068] 10 , there is shown a vehicle, such as a ground-based vehicle, an aircraft, a watercraft, a spacecraft, or a satellite 2000. The vehicle 2000 includes a polarization converter 100. The vehicle 2000 may include an antenna system 1000 as described with reference to FIG. 9 . In other words, the vehicle may include a navigation system having the antenna system 1000.

[0069] Referring to FIG. 11 , the principle of a methodology according to an embodiment is illustrated. The method converts linearly polarized radiation into circularly polarized radiation. Step 3000 includes providing a polarization converter 100, an antenna system 1000, or a vehicle 2000, such as a ground vehicle, an aircraft, or a watercraft, according to an embodiment. Step 3200 includes disposing a first element array layer, a dielectric layer, and a second element array layer on a ground plane. The ground plane serves as a reflective surface from which waves are reflected. Step 3400 includes illuminating the device with linearly polarized radiation, and the reflected radiation is circularly polarized. The linear-to-circular polarization conversion occurs as a result of interaction with the element array layer, particularly its anisotropic properties.

[0070] 12 , the principle of a methodology according to an embodiment is illustrated. The method is a method for manufacturing a linear-to-circular polarization converter 100. Step 4000 comprises providing a first element array layer extending in a plane and a second element array layer extending in a plane, each element array layer having first and second axes parallel to the plane of the respective element array layer, the first and second axes being perpendicular axes, and one or both of the element array layers exhibiting anisotropic spatial properties. Step 4200 comprises laminating the first element array layer comprising a first array of spaced-apart conductive dipole elements, the second element array layer comprising a second array of spaced-apart conductive dipole elements, and a dielectric layer extending in the plane separating the first and second element array layers.

[0071] The polarization converter 100 described above finds applications and advantages in satellite, communication, navigation, and sensing systems. For example, in satellite applications, such converters can be used to minimize the effects of Faraday rotation caused by the ionosphere. Further advantages are found in multipath propagation and rain clutter suppression.

[0072] At least some of the exemplary embodiments described herein may be constructed, in part or entirely, using dedicated, specialized hardware. As used herein, terms such as "component" may include, but are not limited to, hardware devices, such as circuits in the form of discrete or integrated components, field programmable gate arrays (FPGAs), or application-specific integrated circuits (ASICs), that perform a particular task or provide related functionality. It will be understood that various combinations of any feature are described herein, and that the described features may be combined in any suitable combination. In particular, features of any one exemplary embodiment may be combined, as appropriate, with features of any other embodiment, except where such combinations are mutually exclusive. Throughout this specification, the terms "comprising" or "comprises" mean including the identified components but not excluding the presence of others. The following is a summary of the claims as originally filed: [1] A polarization converter, a first element array layer extending in a plane comprising a first array of spaced apart conductive dipole elements; a second element array layer extending in a plane comprising a second array of spaced apart conductive dipole elements; a dielectric layer extending in a plane separating the first element array layer and the second element array layer; Equipped with each element array layer has first and second axes parallel to the plane of the respective element array layer, the first and second axes being vertical axes; A polarization converter, wherein one or both of the element array layers exhibit anisotropic spatial properties. [2] The polarization converter according to [1], wherein one or both of the arrays of dipole elements exhibit anisotropic spatial properties. [3] The linear-to-circular polarization converter of [2], wherein one or both of the arrays of dipole elements have a first periodicity measured along the first axis and a second periodicity measured along the second axis, the second periodicity being different from the first periodicity. [4] The polarization converter according to [3], wherein the first element array layer and the second element array layer have the same first and second periodicities. [5] A polarization converter according to any one of [1] to [4], wherein the dipole elements of the second element array layer are each arranged laterally displaced relative to the dipole elements of the first element array layer. [6] A polarization converter as described in [5], wherein the dipole elements of the second element array layer are each arranged laterally displaced along the first axis relative to the dipole elements of the first element array layer. [7] A polarization converter as described in [6], wherein the dipole elements of the second element array layer are aligned laterally along the second axis relative to the dipole elements of the first element array layer. [8] A polarization converter according to any one of [1] to [7], wherein the plurality of dipole elements of the first element array layer and / or the second element array layer exhibit anisotropic spatial characteristics. [9] The polarization converter described in [8], wherein each dipole element has a first dimension measured along the first axis and a second dimension measured along the second axis, and the first and second dimensions are different.

[10] A polarization converter described in any one of [1] to [9], wherein, in a plan view, one region of the dipole elements of the first element array layer overlaps with one or more regions of the dipole elements of the second element array layer.

[11] A polarization converter as described in

[10] , wherein, in a plan view, 20 to 30% of the length of one of the dipole elements of the first element array layer overlaps with one or more regions of the dipole elements of the second element array layer.

[12] A polarization converter according to any one of [1] to

[11] , comprising a ground plane, wherein the first element array layer, the dielectric layer, and the second element array layer are arranged on the ground plane.

[13] An antenna system for a communication device, comprising: an antenna arranged to generate linearly polarized electromagnetic radiation; [1] to

[12] , and An antenna system comprising:

[14] A vehicle comprising the antenna system according to

[13] .

[15] A method for manufacturing a polarization converter, comprising: providing a first element array layer extending in a plane and a second element array layer extending in a plane, each element array layer having first and second axes parallel to the plane of the respective element array layer, the first and second axes being perpendicular axes, and one or both of the element array layers exhibiting anisotropic spatial properties; the first element array layer comprising a first array of spaced apart conductive dipole elements; the second element array layer comprising a second array of spaced apart conductive dipole elements; a dielectric layer extending in a plane separating the first element array layer and the second element array layer; and laminating the A method comprising:

Claims

1. A polarization converter, a first element array layer extending in a plane comprising a first array of spaced apart conductive dipole elements; a second element array layer extending in a plane comprising a second array of spaced apart conductive dipole elements; a dielectric layer extending in a plane separating the first element array layer and the second element array layer; Equipped with each element array layer has first and second axes parallel to the plane of the respective element array layer, the first and second axes being vertical axes; one or both of the element array layers exhibit anisotropic spatial properties; the dipole elements of the second element array layer are laterally displaced along the first axis relative to the dipole elements of the first element array layer, the dipole elements of the second element array layer are respectively positioned in lateral alignment along the second axis with the dipole elements of the first element array layer. Polarization converter.

2. 10. The polarization converter of claim 1, wherein one or both of said arrays of dipole elements exhibit anisotropic spatial properties.

3. 3. The linear to circular polarization converter of claim 2, wherein one or both of the arrays of dipole elements have a first periodicity measured along the first axis and a second periodicity measured along the second axis, the second periodicity being different from the first periodicity.

4. The polarization converter according to claim 3 , wherein the first element array layer and the second element array layer have the same first and second periodicities.

5. The polarization converter according to claim 1 , wherein the plurality of dipole elements of the first element array layer and / or the second element array layer exhibit anisotropic spatial characteristics.

6. 6. The polarization converter of claim 5, wherein each dipole element has a first dimension measured along the first axis and a second dimension measured along the second axis, the first and second dimensions being different.

7. 2. The polarization converter according to claim 1, wherein, in a plan view, one region of the dipole elements of the first element array layer overlaps with one or more regions of the dipole elements of the second element array layer.

8. 8. The polarization converter of claim 7, wherein, in a plan view, 20 to 30% of the length of one of the dipole elements of the first element array layer overlaps with one or more regions of the dipole elements of the second element array layer.

9. The polarization converter of claim 1 , further comprising a ground plane, wherein the first element array layer, the dielectric layer, and the second element array layer are disposed on the ground plane.

10. 1. An antenna system for a communication device, comprising: an antenna arranged to generate linearly polarized electromagnetic radiation; The linear-circular polarization converter according to claim 1; An antenna system comprising:

11. A vehicle comprising the antenna system of claim 10.

12. A method for manufacturing a polarization converter, comprising the steps of: providing a first element array layer extending in a plane and a second element array layer extending in a plane, each element array layer having first and second axes parallel to the plane of the respective element array layer, the first and second axes being perpendicular axes, and one or both of the element array layers exhibiting anisotropic spatial properties; the first element array layer comprising a first array of spaced apart conductive dipole elements; the second element array layer comprising a second array of spaced apart conductive dipole elements; laminating a dielectric layer extending in a plane separating the first element array layer and the second element array layer, wherein the dipole elements of the second element array layer are each laterally displaced along the first axis relative to the dipole elements of the first element array layer, and the dipole elements of the second element array layer are each laterally aligned along the second axis relative to the dipole elements of the first element array layer; A method comprising:

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