Wideband horizontally polarized antenna

Abstract

The present disclosure relates to an antenna device (1) having an antenna mounted inside a radome (3). The antenna device (1) further comprises a mounting device arranged to mount the antenna device (1) to an antenna platform (7a, 7b, 7c). The antenna is a tapered slot antenna (2), the radome (3) has an aerodynamic shape, and the mounting device comprises two antenna fixing means (5), antenna radio frequency connectors (6) arranged to interact with the corresponding antenna platform (7a, 7b, 7c) fixing means, and antenna platform radio frequency connectors arranged on the antenna platforms (7a, 7b, 7c).

Description

[Technical Field]

[0001] The present disclosure relates to an antenna apparatus including an antenna mounted inside a radome, the antenna apparatus further including a mounting device attached to the radome arranged to mount the antenna apparatus to an antenna platform, and a method for receiving and transmitting radio frequency signals having horizontal polarization and propagation perpendicular to the direction in which the antenna platform is moving. [Background technology]

[0002] Vehicle-mounted radio frequency (RF) antennas can be used in a variety of applications. One application area is radar applications, such as air or ground traffic control, marine radar for locating landmarks and other vessels, radar astronomy, and various defense applications.

[0003] Another application is electronic warfare (EW), in which RF antennas use the electromagnetic (EM) spectrum to control the spectrum, attack an enemy, or hinder an enemy assault. The objective of electronic warfare is to deny an enemy an advantage over or ensure friendly unimpeded access to the EM spectrum. EW can be applied from manned and unmanned air, sea, land, and / or space-based platforms and can target personnel, communications, radar, or other assets.

[0004] The most common vehicle-mounted antenna for very high frequency (VHF) and ultra high frequency (UHF) radio frequencies is the blade antenna. Monopole antennas, such as blade antennas, are placed inside the radome. Monopole antennas are well known for having a "donut-shaped" radiation pattern around the z-axis, such that they have full coverage in the xy plane but no coverage in the ±z directions. See, for example, CA Balanis, "Antenna Theory, analysis and design," ISBN 978-1118642061. The polarization of a blade antenna is in the z-direction.

[0005] Thus, a vehicle-mounted blade antenna can be used to achieve vertical polarization with full 360° coverage in a horizontal plane relative to the vehicle, such as an aircraft, while horizontal polarization can be used primarily in the forward or aft direction of the vehicle, rather than to the side, as is the case with conventional blade antennas.

[0006] In the aircraft example, one way to achieve horizontal polarization relative to the plane of the aircraft is to mount a horizontally polarized dipole at a distance above the aircraft's metal fuselage. This approach has two challenges. First, it requires a quarter wavelength distance from the metal ground plane, which is difficult due to the long wavelengths at VHF frequencies. Another challenge is that there is poor radiation efficiency in the horizontal plane due to image currents in the ground plane.

[0007] One method for reducing the distance above the ground plane is presented in Daniel Sievenpiper et al., "High-Impedance Electromagnetic Surfaces with a Forbidden Frequency Band," IEEE Transactions on Antennas and Propagation, Vol. 47, No. 11, November 1999. However, to the applicant's knowledge, this configuration has not yet reached commercial use for aircraft applications due to the narrow bandwidth and size requirements for the high-impedance ground plane.

[0008] Another solution is presented by Luca Scorrano et al., "Dual-polarization DF Array for airborne SIGINT in VHF / UHF bands," Proceedings of the 44th European Microwave Conference, 8-10, October 2014. Like blade antennas, this antenna is narrowband, resulting in insufficient radiation efficiency at lower frequencies for some applications, and performance is limited by the distance from the ground plane.

[0009] Another way to achieve horizontal polarization towards the side of the aircraft would be to place patch antennas on the sides of the aircraft, but patch antennas require a relatively large area on the side of the aircraft and are narrowband.

[0010] WO 2019 / 143275 A1 discloses an antenna installation using a log-periodic antenna. With this configuration, horizontal polarization can be achieved, but only in the forward or aft direction relative to the aircraft.

[0011] Therefore, there is a need for an improved antenna arrangement intended to provide reception and transmission of RF waves with horizontal polarization with high radiation efficiency over a wide bandwidth. Summary of the Invention

[0012] The object of the present disclosure is to provide an antenna device that addresses the above-mentioned problems. This object is achieved by the technical features contained in the characterizing parts of independent claims 1 and 9. The dependent claims contain advantageous embodiments, further developments and variations of the antenna device.

[0013] For reference, the local coordinate system x,y,z (lowercase) is the local coordinate system used for the antenna device, where the x-axis is the longitudinal axis, the y-axis is the horizontal axis, and the z-axis is the vertical axis. The coordinate system X,Y,Z (uppercase) is the local coordinate system used for the antenna platform on which the antenna device is mounted, where the x-axis is the vertical axis, the y-axis is the horizontal axis, and the z-axis is the longitudinal axis.

[0014] The present disclosure relates to an antenna apparatus including an antenna mounted inside a radome, the antenna apparatus further including a mounting device arranged to mount the antenna apparatus to an antenna platform, the antenna apparatus being a tapered slot antenna, the radome having an aerodynamic shape, and the mounting device including two antenna fastening means, an antenna radio frequency connector arranged to interact with the corresponding antenna platform fastening means, and an antenna platform radio frequency connector arranged on the antenna platform.

[0015] The most common mounting configuration for blade antennas is vertical mounting on the top or bottom of an aircraft, i.e., the z-axis of the antenna is aligned with the x-axis of the antenna platform. This configuration achieves total RF coverage in the horizontal YZ plane with vertical polarization. This is a common type of mounting for wireless communication antennas.

[0016] Horizontal polarization is achieved when the blade antenna is mounted with its z-axis in the horizontal YZ plane, aligned with the Y-axis of the antenna platform. However, due to the toroidal radiation pattern, this results in coverage only in the forward and aft directions relative to the aircraft. Therefore, coverage to the sides of the antenna platform, such as an aircraft, cannot be achieved with this antenna configuration. This configuration can be used for instrument landing systems (ILS), which require horizontal polarization in the forward direction.

[0017] However, it would be highly advantageous for electronic warfare applications that have horizontal polarization and radiation along the positive and negative Y-axes, or propagation perpendicular to the direction the antenna platform to which the antenna apparatus is mounted is moving. One exemplary application for the antenna apparatus is for an airborne electronic warfare platform moving in a racetrack flight pattern, where the antenna apparatus can be used for both standoff jamming and surveillance of possible threats.

[0018] The antenna device used in this disclosure is a tapered slot antenna mounted in a radome so that its mechanical and aerodynamic design resembles a previously known blade antenna. Therefore, the antenna device's appearance is similar to that of a blade antenna. Because the tapered slot antenna is an end-fire antenna, the radiation pattern has a maximum in the z-direction and is polarized along the y-axis. The bandwidth and gain of the tapered slot antenna are both greater than those of the blade antenna.

[0019] The antenna device according to the present disclosure satisfies the following specifications:

[0020] 1. Horizontally polarized antenna with z-direction coverage of the antenna device such that coverage to the side of the antenna platform can be achieved as an air, land, or water vehicle. 2.Antenna with large bandwidth 3. The resulting antenna device is easy to install 4. The resulting antenna device has an aerodynamic cross section 5. The resulting antenna device has high radiation efficiency and low return loss For the tapered slot antenna, any tapering function may be used, such as an exponentially tapered slot antenna, a linearly tapered slot antenna, a continuous width slot antenna, a double exponentially tapered slot antenna, a step slot antenna, a step constant tapered slot antenna, a tangentially tapered slot antenna, a parabolic tapered slot antenna, a linear constant tapered slot antenna, an exponentially constant tapered slot antenna, or a piecewise linearly tapered slot antenna.

[0021] Various tapered slot configurations can be selected depending on the desired characteristics of the antenna in the antenna device.

[0022] The radome material may be, for example, one of plastic, composite glass, fiberglass, or quartz.

[0023] The radome material can be part of the antenna device. Depending on the desired characteristics of the antenna device, the dielectric constant of the material can be adapted depending on the material chosen for the radome. The size of the antenna can be adapted, for example, by adapting the dielectric constant of the radome.

[0024] The antenna platform may be an air vehicle, such as an airplane or an unmanned aerial vehicle, and the antenna unit is positioned essentially on a vertical plane of the air vehicle such that the antenna unit is positioned to receive and transmit radio frequency signals that are horizontally polarized and propagate perpendicular to the direction in which the antenna platform is moving.

[0025] As indicated above, an antenna apparatus according to the present disclosure is advantageous for electronic warfare platforms, such as aircraft moving in a racetrack flight pattern, that can be used for both standoff jamming and surveillance of potential threats. The unmanned aerial vehicle can be an unmanned combat aerial vehicle.

[0026] The antenna platform may also be a manned or unmanned land vehicle. The antenna platform may also be a manned or unmanned water vehicle, such as a manned or unmanned boat or warship.

[0027] Other types of electronic warfare platforms, such as armored vehicles and water vehicles such as ships and boats, may also successfully utilize antenna platforms according to the present disclosure. The antenna platforms may be manned or unmanned, i.e., unmanned ground vehicles or unmanned water vehicles.

[0028] The antenna and platform radio frequency connectors may be subminiature Version A coaxial connectors.

[0029] For ease of installation, the antenna device and the antenna platform are provided with compatible radio frequency connectors. One example of a radio frequency connector is the Subminiature Version A (SMA) coaxial connector, which offers ease of use and good characteristics for the RF used. Alternatives to the SMA connector are, for example, the Subminiature Version C (SMC) coaxial connector, the Bayonet Neil-Concelmann (BNC) connector, the Threaded Neil-Concelmann (TNC) connector, or the Type N connector.

[0030] The present disclosure also relates to an array antenna comprising a plurality of antenna units as described above, the array antenna being formed by the antenna units being arranged along essentially the same linear extension of the antenna platform, or in a pattern where at least some of the antenna units are separated along the Z-axis of the antenna platform.

[0031] A plurality of antenna units may be mounted, for example, along the length of an aircraft to form an array antenna, which may be used for direction finding (DF) in electronic surveillance (ES) and / or to achieve high gain against electronic attack (EA).

[0032] The present disclosure also relates to a method of receiving and transmitting a signal having horizontal polarization and radiation along positive and negative Y-axes, the method comprising: providing an antenna arrangement by mounting a tapered slot antenna inside an aerodynamically shaped radome; further providing a mounting device for the antenna device, the mounting device comprising two antenna fixing means and one antenna radio frequency connector; disposing, on a vertical surface of the antenna platform, an antenna platform fastening means and an antenna platform radio frequency connector arranged to interact with the antenna fastening means and the antenna radio frequency connector; mounting the antenna device on an antenna platform; and connecting the antenna device to a control system through an antenna radio frequency connector and an antenna platform radio frequency connector; Includes:

[0033] The method provides the advantages described above. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a diagram illustrating a schematic diagram of a prior art antenna device; [Figure 2] 1 is a diagram illustrating a schematic diagram of an antenna device according to the present disclosure; [Figure 3a] 1 shows a schematic diagram of an antenna platform in the form of an aircraft having an antenna apparatus according to the present disclosure; [Figure 3b] FIG. 1 is a diagram illustrating a schematic of an antenna platform in the form of an aircraft having an array antenna according to the present disclosure. [Figure 4] FIG. 1 shows a schematic diagram of an antenna platform in the form of an airplane moving in a racetrack flight pattern. [Figure 5] 1 is a diagram illustrating a schematic representation of an antenna platform in the form of a ground vehicle having an antenna apparatus according to the present disclosure; [Figure 6] 1 is a diagrammatic representation of an antenna platform in the form of a water vehicle having an antenna apparatus according to the present disclosure; DETAILED DESCRIPTION OF THE INVENTION

[0035] In the figures, the antenna is defined by a coordinate system x,y,z (lowercase), where the x-axis is the longitudinal axis, the y-axis is the horizontal axis, and the z-axis is the vertical axis. The antenna platform is defined by a coordinate system X,Y,Z (uppercase), where the x-axis is the vertical axis, the y-axis is the horizontal axis, and the z-axis is the longitudinal axis.

[0036] 1 shows a schematic diagram of a prior art blade antenna arrangement 101. The prior art antenna arrangement 101 comprises a shaped monopole antenna 102 disposed inside a radome 103. The radome is typically opaque to optical frequencies but not to RF frequencies, and therefore its boundary is outlined by a dash-dot line. The blade antenna 102 is mounted to a ground plane 104 and positioned so as to be mechanically connectable using two antenna fixation means 105 and electronically connectable to an antenna platform such as an aircraft (not shown) using an antenna radio frequency connector 106.

[0037] Prior art antenna assembly 101 is a typical aircraft-mounted antenna for VHF and UHF radio frequencies and was described in the "Background." Advantages of blade antenna 102 include ease of installation, exemplified by the two screws that serve as antenna fixation means 105 shown in FIG. 1, and the aerodynamic cross section of radome 103. However, blade antenna 102 does not provide horizontal polarization, or propagation perpendicular to the direction in which the antenna platform to which the antenna assembly is attached is moving. For simplicity, the antenna feed and other known details necessary for the antenna to function are not shown.

[0038] Figure 2 shows a schematic diagram of an antenna arrangement 1 according to the present disclosure. In the antenna arrangement 1 of Figure 2, the blade antenna 102 of Figure 1 is replaced by a tapered slot antenna 2 mounted on a ground plane 4. Furthermore, the radome 3 has an aerodynamic shape. The mounting arrangement comprises two antenna fixing means 5, an antenna radio frequency connector 6 arranged to interact with corresponding antenna platform fixing means (not shown), and an antenna platform radio frequency connector (not shown) arranged on the antenna platform (not shown).

[0039] Since the tapered slot antenna 2 is an end-fire antenna, the radiation pattern has a maximum in the z-direction and is polarized along the y-axis. Both the bandwidth and the realized gain or radiation efficiency of the tapered slot antenna 2 are greater than those of a blade antenna, leading to a number of advantages compared to the prior art antenna arrangement 1 of FIG.

[0040] Depending on the desired characteristics, many variations of the tapered slot antenna 2 may be used with the antenna device 1 according to the present disclosure. For simplicity, the antenna feed and other known details necessary for the antenna to function are not shown.

[0041] Figure 3a shows a schematic representation of an antenna platform 7a in the form of an airplane having an antenna arrangement 1 according to the present disclosure. Figure 3a shows an example placement of the antenna arrangement 1 on the aircraft to take advantage of the advantages offered by the antenna arrangement 1, namely the z-direction radiation pattern of the tapered slot antenna 2 with polarization along the y-axis.

[0042] Figure 3b shows a schematic diagram of an antenna platform 7a in the form of an aircraft having an array antenna 8 according to the present disclosure. A plurality of antenna units 1 may be installed along the length of the aircraft to form the array antenna 8 according to Figure 3b. The array antenna 8 may be used for direction finding (DF) in electronic surveillance (ES) and to achieve high gain against electronic attack (EA).

[0043] FIG. 4 shows a schematic representation of an antenna platform 7a in the form of an aircraft moving in a racetrack flight pattern. The antenna unit 1 and / or array antenna 8 are advantageous for electronic warfare (EW) and signal intelligence gathering aircraft. Antenna units 1 that meet criteria 1-5 above are of interest for racetrack flight because they are used for both standoff jamming and surveillance. In FIG. 4, multiple threats 9 are shown within range of the antenna unit 1 and / or array antenna 8, and standoff jamming and / or surveillance can be performed against the threats 9, as indicated by the arrows. The arrows represent signal reception and transmission.

[0044] Figure 5 shows schematically an antenna platform 7b in the form of a ground vehicle having an antenna apparatus 1 according to the present disclosure. Similar to the airborne antenna platform 7a of Figure 4, a land-based antenna platform 7b can benefit from having one or more antenna apparatus 1 installed as described above. Although only one antenna apparatus is shown, it should be understood that the antenna platform 7b could alternatively comprise a linear antenna array 8 according to Figure 3b.

[0045] Figure 6 shows schematically an antenna platform 7c in the form of a water vehicle having an antenna apparatus 1 according to the present disclosure. Similar to the airborne antenna platform 7a of Figure 4 and the land-based antenna platform 7b of Figure 5, the water vehicle can benefit from having one or more antenna apparatus 1 installed as described above. Although only one antenna apparatus is shown, it should be understood that the antenna platform 7c could alternatively comprise a linear antenna array 8 according to Figure 3b.

[0046] In other words, the antenna platforms 7a, 7b, 7c are suitable for implementing a method for receiving and transmitting radio frequency signals with horizontal polarization and propagation perpendicular to the direction in which the antenna platforms (7a, 7b, 7c) are moving. providing an antenna arrangement 1 by mounting a tapered slot antenna 2 inside an aerodynamically shaped radome 3; further providing the antenna device 1 with a mounting device comprising two antenna fixing means 5 and one antenna radio frequency connector 6; - arranging, on the vertical surface of the antenna platforms 7a, 7b, 7c, the antenna platform 7a, 7b, 7c fixing means and the antenna platform radio frequency connector arranged to interact with the antenna fixing means 5 and the antenna radio frequency connector 6; a step including mounting the antenna device 1 on the antenna platform 7a, 7b, 7c and connecting the antenna device 1 to a control system through the antenna radio frequency connector 6 and the antenna platform radio frequency connector; Includes:

[0047] The control system is an RF system, such as an electronic warfare system and / or a radar system.

[0048] In the context of this disclosure, an aerodynamic shape means that the shape of the radome 3 reduces drag from passing through the air compared to a non-aerodynamic shape. Examples of radomes 3 having an aerodynamic shape can be found in U.S. Patent No. 4,072,952 and are available from numerous blade antenna manufacturers.

[0049] The tapered slot antenna 2 may be printed or etched onto a substrate with a microstrip feedline, printed or etched onto a dielectric substrate with a stripline feedline, fabricated from a single layer of metal with a microstrip feedline, printed or etched onto a substrate with a differential feedline, and fabricated from a single layer of metal with a differential feedline. Stepped slot antennas are also known as notch elements.

[0050] As will be realized, the invention is capable of modifications in various obvious respects without departing from the scope of the appended claims. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.

Claims

1. an antenna device (1) comprising an antenna mounted inside a radome (3), further comprising a mounting device attached to the radome (3) arranged to mount the antenna device (1) to an antenna platform (7a, 7b, 7c); The antenna is a tapered slot antenna (2), An antenna device (1), wherein the mounting device comprises two antenna fixing means (5), antenna radio frequency connectors (6) arranged to interact with corresponding antenna platform (7a, 7b, 7c) fixing means, and antenna platform radio frequency connectors arranged on the antenna platforms (7a, 7b, 7c), 1. An antenna device (1), characterized in that the antenna device (1) is configured to be mounted on a vertical surface of the antenna platform (7a) so that the antenna device (1) is positioned to receive and transmit radio frequency signals that are horizontally polarized and propagate perpendicular to the direction in which the antenna platform (7a) is moving.

2. 2. The antenna device (1) of claim 1, wherein the tapered slot antenna (2) is one of an exponentially tapered slot antenna, a linearly tapered slot antenna, a continuous width slot antenna, a double exponentially tapered slot antenna, a step slot antenna, a step constant tapered slot antenna, a tangentially tapered slot antenna, a parabolic tapered slot antenna, a linear constant tapered slot antenna, an exponentially constant tapered slot antenna, or a piecewise linearly tapered slot antenna.

3. 3. The antenna arrangement (1) according to claim 1 or 2, wherein the material of the radome (3) is one of plastic, composite glass, fiberglass, or quartz.

4. The antenna arrangement (1) according to any one of claims 1 to 3, wherein the antenna platform (7a) is an air vehicle.

5. The antenna arrangement (1) according to any one of claims 1 to 3, wherein the antenna platform (7b) is a manned or unmanned land vehicle.

6. The antenna arrangement (1) according to any one of claims 1 to 3, wherein the antenna platform (7c) is a manned or unmanned waterborne vehicle.

7. The antenna arrangement (1) according to any one of claims 4 to 6, wherein the antenna radio frequency connector (6) and the platform radio frequency connector are subminiature version A coaxial connectors.

8. An array antenna (8) comprising a plurality of antenna devices (1) according to any one of claims 1 to 7, wherein the antenna devices (1) are arranged along the same linear extension of an antenna platform (7a, 7b, 7c).

9. 1. A method for receiving and transmitting radio frequency signals with horizontal polarization and propagation perpendicular to the direction in which an antenna platform (7a, 7b, 7c) is moving, comprising: providing an antenna device (1) by mounting a tapered slot antenna (2) inside a radome (3); providing the antenna device (1) with a mounting device comprising two antenna fixing means (5) and one antenna radio frequency connector (6); mounting, on a vertical surface of the antenna platform (7a, 7b, 7c), an antenna platform (7a, 7b, 7c) fixing means and an antenna platform radio frequency connector arranged to interact with said antenna fixing means (5) and an antenna radio frequency connector (6); mounting the antenna device (1) on the antenna platform (7a, 7b, 7c) so that the antenna device (1) is positioned to receive and transmit radio frequency signals that are horizontally polarized and propagate perpendicular to the direction in which the antenna platform (7a) is moving; and connecting the antenna device (1) to a control system through the antenna radio frequency connector (6) and the antenna platform radio frequency connector; A method comprising:

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