GB2458123A - Dual s-band and x-band active radar transponder - Google Patents

Dual s-band and x-band active radar transponder Download PDF

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Publication number
GB2458123A
GB2458123A GB0804014A GB0804014A GB2458123A GB 2458123 A GB2458123 A GB 2458123A GB 0804014 A GB0804014 A GB 0804014A GB 0804014 A GB0804014 A GB 0804014A GB 2458123 A GB2458123 A GB 2458123A
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United Kingdom
Prior art keywords
band
signal
antenna
transmitting
amplified
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB0804014A
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GB0804014D0 (en
Inventor
Peter Austin Dods Munro
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Individual
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Individual
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Priority to GB0804014A priority Critical patent/GB2458123A/en
Publication of GB0804014D0 publication Critical patent/GB0804014D0/en
Priority to GB0903245A priority patent/GB2457385A/en
Publication of GB2458123A publication Critical patent/GB2458123A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
    • G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
    • G01S13/767—Responders; Transponders
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/14—Reflecting surfaces; Equivalent structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/28—Combinations of substantially independent non-interacting antenna units or systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q23/00—Antennas with active circuits or circuit elements integrated within them or attached to them
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
    • H01Q9/28—Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

A dual band (s-band 2-4 GHz, x-band 8-12 GHz) active radar reflector installation is provided. The installation comprises a radome which houses a means for receiving an incoming s-band radar signal 32; an amplifier for amplifying the received s-band signal 44; means for transmitting the amplified s-band signal 34; means for receiving an incoming x-band radar signal 36; an amplifier for amplifying the received x-band signal 46 and means for transmitting the amplified x-band signal 38. Each of the means for receiving and transmitting are located within the radome. The s-band receive and transmit antennas may be patch antennas (see Figure 3).

Description

A Device for Enhancing Detection of a Marine Vessel The present invention relates to a device for enhancing detection of a marine vessel, in particular to enhancing the detection thereof by radar.
Ships use radar as their primary means of detecting other vessels in the vicinity, in order to avoid collision therewith. Different band designations are used across the radar frequency range to identify different band widths which may be used for particular applications. Marine applications generally use part of the s-band (nominal frequency range 2-4 GHz) and/or part of the x-band (nominal frequency range of 8-12 GHz).
Larger ships, in particular, are required to carry equipment that operates in both in the s-band and in the x-band.
Small vessels from leisure craft up to approximately 150 GRT are often made of materials having very poor reflection characteristics for radar signals, for example, wood and glass reinforced plastic (GRP). Consequently, the visibility of small vessels to radar is poor and so they generally carry a passive radar reflector. Indeed, it is considered by the International Maritime Organisation (IMO) that it is essential that small vessels be equipped with a radar reflector to enhance their radar return and thus enhance their visibility to radar.
One type of passive reflector is known as the octahedral reflector and comprises a number of surfaces, say metallic plates, located in different planes, generally perpendicular to one another in order to present a reflective surface from more than one direction. A more sophisticated octahedral reflector can be formed as an array of devices stacked together to enhance the reflective properties thereof. An alternative type of passive reflector is the Luneberg lens which is formed as a set of concentric spherical shells of different dielectric constant.
The underlying principle of a radar reflector is to enhance the radar cross-section (RCS) of the vessel to which it is attached. The ACS of a passive reflector is a function of the size of the reflector and the frequency of an incident radar signal. In practice, passive radar reflectors can reflect at any radar frequency and therefore are able to display some reflective capability in both the s-band and the x-band. However, the RCS of any particular reflector in the s-band is typically ten percent of the RCS of that same reflector in the x-band. Since the RCS represented by a passive reflector is a function of the size of the reflector, an improved RCS can be achieved by increasing the size of the reflector. In order to achieve the RCS required by regulatory standards in this field, a passive reflector would become cumbersome and weighty which can, in turn, adversely affect the stability of the vessel. It is, therefore, difficult for a passive reflector to achieve this standard.
Active radar reflectors are known which operate in the x-band. An active reflector receives an interrogating radar signal, amplifies that signal and broadcasts the amplified signal in all directions in the azimuth plane, to enable the return to be detected by the source of the signal. Active reflectors are able to achieve a higher RCS in a smaller device than is possible within a passive reflector.
It is an aim of the present invention to address some of the disadvantages presented above whilst providing increased visibility for a vessel within the marine radar bands.
According to a first aspect, the present invention provides a dual band active radar reflector installation comprising: a radome; means for receiving an incoming radar signal, the signal having a frequency in a marine radar band; an amplifier for amplifying the received signal; and means for transmitting the amplified signal, the means for receiving and the means for transmitting being located within the radome.
Larger vessels are required, by Safety of Life at Sea (SOLAS) regulations, to be equipped with both x-band and s-band radar. In providing an antenna for receiving a signal in both the s-band and the x-band and the facility to amplify and re-transmit this signal, the visibility to radar of a small vessel may be significantly enhanced by the device of the present invention. The larger vessel has an increased opportunity to detect a smaller vessel carrying the device of the present invention and, therefore, to avoid a collision therewith.
The amplifier may be located within the radome. The means for receiving may comprise a first receiving antenna element configured to receive an incoming signal having a frequency in the s-band and a second receiving antenna element, configured to receive an incoming signal having a frequency in the x-band. The means for transmitting the amplified signal may comprise a first transmitting antenna element, configured to transmit an amplified signal having a frequency in the s-band and a second transmitting antenna element, configured to transmit an amplified signal having a frequency in the x-band.
According to a second aspect, the invention provides a device for enhancing detection of a marine vessel comprising: a first s-band antenna configured to receive an incoming signal in the s-band; an amplifier for amplifying the received s-band signal; and means for transmitting the amplified s-band signal.
In providing a device having an antenna for receiving a signal in the s-band and the facility to amplify and re-transmit this signal, the visibility to radar of a small vessel to a larger source vessel having s-band radar capability, may be significantly enhanced by such a device.
The means for transmitting may be provided by the first s-band antenna. The device may comprise a second s-band antenna for transmitting the amplified s-band signal.
The second s-band antenna may be configured to transmit omnidirectionally around the azimuth plane.
The, or each, s-band antenna may be a folded dipole antenna, such as a cylindrical folded dipole antenna.
The first s-band antenna may be configured to receive a signal in the range of 2.9 to 3.1GHz, namely the marine part of the s-band frequency range.
The aforementioned device may comprise: a first x-band antenna, configured to receive an incoming signal in the x-band; an amplifier for amplifying the received x-band signal; and means for transmitting the amplified x-band signal.
The means for transmitting may be provided by the first x-band antenna or, alternatively, the device may comprise a second x-band antenna for transmitting the amplified x-band signal and may be, preferably, configured to transmit omnidirectionally in the azimuth plane.
The, or each, x-band antenna may be a slotted waveguide antenna, the first x-band antenna may be configured to receive a signal in the range of 9.3 to 9.5 GHz, namely the marine part of the x-band frequency range.
An active radar reflector installation may be provided comprising a radome together with the aforementioned device, mounted within the radome. The installation may be configured to achieve a radar cross section of at least 8m2 throughout the azimuth when the vessel upon which it is installed experiences 1 0° heel.
The invention will now be described in more detail, by way of example only, with reference to the drawings in which: Figure 1 represents an s-band active radar reflector; Figure 2 represents a dual band active radar reflector; and Figure 3 represents an alternative dual band active reflector.
Figure 1 illustrates an active radar reflector device 10, comprising a first antenna 12 for receiving an incoming signal. In this embodiment the first antenna 12 is a cylindrical folded dipole antenna, so dimensioned to receive incoming signals having a frequency in the s-band. Alternatively antenna 12 could be provided by a patch antenna (not shown). A patch antenna is typically larger and heavier than the folded dipole used in the first embodiment and would, therefore, be more appropriate for use in a slightly larger vessel rather than a leisure craft.
A second antenna 14 is provided for transmitting a signal therefrom. Each antenna 12, 14, as illustrated, is connected to an amplifier assembly 16 comprising an amplifier 18.
The antennae 12, 14 and the amplifier assembly 16 are each mounted within a radome 20. The radome 20 comprises a material having a low dielectric constant such as a plastics material e.g. polyvinylchloride (PVC) which is effectively transparent to radar. The radome 20 is provided for protection of the antennae 12, 14 and the amplifier 18, collectively referred to as the "components", located therewithin. The components are thus protected from wear and damage which may be caused by weather, sea water and wild life. The components are also shielded from precipitation and ice formation which, for example, may affect the receiving or transmitting capability thereof.
Coaxial cable is provided between each antenna 12, 14 and the amplifier 18. As each of these components 12, 14, 18 are co-located within the radome 20, the length of the expensive coaxial cable can be minimised and damage to the cable can be avoided as it does not pass out of the radome 20. Alternatively, the antennae 12, 14 may be directly connected to the amplifier 18 using a gold plated pin (not illustrated). A power cable 22 passes from the device 10 to a user interface of the device (not shown) through a gland 24 in the radome 20. Operation of the device 10 is initiated/powered remotely, by a user, via this cable 22.
In operation, a source vessel such as a ship transmits an interrogating signal having a frequency in the s-band. When the receive antenna 12 receives such a signal, the signal is passed to the amplifier 18 for the signal to be amplified, thus effectively increasing the RCS thereof. The amplified signal is then broadcast from the transmit antenna 14 for subsequent detection by the source vessel.
A second embodiment of the device is illustrated in Figure 2. A dual band device 30 is illustrated, having a number of antenna elements 32, 34, 36, 38 and an amplifier assembly 40 each housed within a radome.
An s-band receive antenna element 32 is provided at one end of the device 30. A corresponding s-band transmit antenna element 34 is provided at a distal end of the device 30. An x-band receive antenna element 36 is provided adjacent to the s-band receive antenna element 32 and is separated therefrom by a spacer element 42. The spacer element 42 serves to isolate the s-band receive antenna element 32 from the x-band receive antenna element 36 whilst allowing the s-band receive antenna element 32 to be supported by the x-band receive antenna element 36. An x-band transmit antenna element 38 is provided adjacent the s-band transmit antenna element 34 and is separated therefrom by a spacer element 42. Again the spacer element 42 not only serves to isolate the s-band transmit antenna element 34 from the x-band transmit antenna element 38 but also allows the s-band transmit antenna element 34 to be supported by the x-band transmit antenna element 38.
An amplifier assembly 40 is provided between and supports the x-band receive antenna element 36 and the x-band transmit antenna element 38. The amplifier assembly 40 comprises a first amplifier 44, associated with the s-band antenna elements 32, 34, and a second amplifier 46, associated with the x-band antenna elements 36, 38. Each antenna element is connected to its respective amplifier using coaxial cable. In this example, the amplifiers 44, 46 are co-located within the housing assembly 40, however, in an alternative embodiment, the amplifiers 44, 46 may be separately located.
Indeed, in each embodiment it is possible for the amplifier circuitry to be located remotely from a radome housing the antenna elements, for example at the bottom of the mast, however in such a configuration, the coaxial connecting cables would need to extend the length of the mast.
As in the first embodiment, the s-band antenna elements 32, 34 are cylindrical, folded dipole antenna elements. The x-band antenna elements 36, 38 are slotted waveguide antenna elements.
In operation, a source vessel such as a ship transmits an interrogating signal having a frequency in either the s-band or the x-band. When the respective receive antenna element 32, 36 receives such a signal, the signal is passed to the amplifier for the signal to be amplified, thus effectively increasing the RCS thereof. The amplified signal is then broadcast from the respective transmit antenna element 34, 38 for subsequent detection by the source vessel.
Figure 3 illustrates an alternative embodiment, in which the s-band antenna elements of device 50 are provided by patch antenna elements. The x-band receive and transmit elements 52, 54 and an amplifier assembly 56 are configured similarly to the second embodiment, illustrated in Figure 2. However, a mounting plate 58 is connected to a distal end of the x-band receiving antenna element 52. An s-band receiving antenna element 60 is cantilevered from this mounting plate 58. The second s-band antenna element 62, configured to transmit signals in the s-band is located about the amplifier assembly 56. As the dimensions of a patch antenna element are somewhat larger than the corresponding cylindrical, folded dipole antenna element of the previous embodiments, the diameter of device 50 will be somewhat larger than that of device 30 of the second embodiment. However, in the presented configuration, the device 50 can be shorter than device 30 which may be easier to accommodate in particular circumstances upon a particular vessel.
The operation of device 50 corresponds to that of device 30 in the second embodiment.
As discussed above, the device 50 comprising patch antenna elements is typically larger and heavier when folded dipole antenna elements are used and, therefore, device 50 is, perhaps, more appropriate for use in a slightly larger vessel rather than a leisure craft.
In alternative embodiments (not illustrated) the transmitting s-band patch antenna element may also be cantilevered from the x-band transmitting element. Further, the x-band antenna elements could also be replaced with patch antenna elements.
In an active radar reflector, the size of an antenna is directly related to the frequency at which it transmits. Consequently, for a particular type of antenna, the dimension of an s-band antenna is anticipated to be significantly larger than that required for a corresponding x-band antenna. An active radar reflector is, ideally, sited at the top of a mast on a small vessel in order to enhance the transmission of the amplified signal even when the vessel is experiencing significant heel. It can be difficult to accommodate the increased foot print associated with a significantly larger antenna on a small leisure craft. Consideration must, therefore, be given to the selection of antennae to be used in the particular reflector installation.
In summary, a device capable of improving the visibility to radar of a vessel upon which it is installed is described. The device represents an active s-band reflector and, in a more sophisticated embodiment represents a dual band active reflector, capable of achieving a significant radar cross section (RCS) that can be readily detected by a source vessel, transmitting an interrogating signal in one of the marine bands. This level of RCS can even be achieved around the azimuth of the vessel when the vessel is experiencing significant heeling angles as may be the case for a small leisure craft such as a yacht. For example the device can readily achieve an RCS of at least 8m2 in all directions around the azimuth plane when the vessel upon which the device is installed is experiencing 1 0° heel.
The device is compact and light weight, so that it can readily be installed at the mast head of such a vessel without adversely affecting the stability thereof. The approximate weight of the device is in the range of 0.8 to 1.5 kg which is a significant advantage when compared to bulky passive devices that typically weigh in the range of 3 to 8 kg.
A further advantage in providing an active device over a passive one is that the reflector detects when an interrogating signal has been received. This permits an alarm to sound upon interrogation, thus alerting a user of the vessel to the presence of the source vessel.

Claims (19)

  1. CLAIMS1. A dual band active radar reflector installation comprising: a radome; means for receiving an incoming radar signal, the signal having a frequency in a marine radar band; an amplifier for amplifying the received signal; and means for transmitting the amplified signal, the means for receiving and the means for transmitting being located within the radome.
  2. 2. An installation according to Claim 1, wherein the amplifier is located within the radome.
  3. 3. An installation according to Claim 1 or Claim 2, wherein the means for receiving comprises a first receiving antenna element configured to receive an incoming signal having a frequency in the s-band and a second receiving antenna element, configured to receive an incoming signal having a frequency in the x-band.
  4. 4. An installation according to any of Claims 1 to 3, wherein the means for transmitting the amplified signal comprises a first transmitting antenna element, configured to transmit an amplified signal having a frequency in the s-band and a second transmitting antenna element, configured to transmit an amplified signal having a frequency in the x-band.
  5. 5. A device for enhancing detection of a marine vessel comprising: a first s-band antenna configured to receive an incoming signal in the s-band; an amplifier for amplifying the received s-band signal; and means for transmitting the amplified s-band signal.
  6. 6. A device according to Claim 5, wherein the means for transmitting is provided by the first s-band antenna.
  7. 7. A device according to Claim 5 or Claim 6, comprising a second s-band antenna for transmitting the amplified s-band signal.
  8. 8. A device according to Claim 7, wherein the second s-band antenna is configured to transmit omnidirectionally around the azimuth plane.
  9. 9. A device according to any of Claims 5 to 8, wherein the, or each, s-band antenna is a folded dipole antenna.
  10. 10. A device according to Claim 9, wherein the folded dipole antenna is a cylindrical folded dipole antenna.
  11. 11. A device according to any of Claims 5 to 10, wherein the first s-band antenna is configured to receive a signal in the range of 2.9 to 3.1GHz.
  12. 12. A device according to any of Claims 5 to 11, comprising: a first x-band antenna, configured to receive an incoming signal in the x-band; an amplifier for amplifying the received x-band signal; and means for transmitting the amplified x-band signal.1 5
  13. 13. A device according to Claim 12, wherein the means for transmitting is provided by the first x-band antenna.
  14. 14. A device according to Claim 12 or Claim 13, comprising a second x-band antenna for transmitting the amplified x-band signal.
  15. 15. A device according to Claim 14, wherein the second x-band antenna is configured to transmit omnidirectionally in the azimuth plane.
  16. 16. A device according to any of Claims 12 to 1 5, wherein the, or each, x-band antenna is a slotted waveguide antenna.
  17. 17. A device according to any of Claims 12 to 16, wherein the first x-band antenna is configured to receive a signal in the range of 9.3 to 9.5 GHz.
  18. 18. An active radar reflector installation comprising: a radome; and a device according to any of Claims 5 to 17, mounted within the radome.
  19. 19. An active radar installation according to Claim 18, configured to achieve a radar cross section of at least 8m2 throughout the azimuth when the vessel upon which it is installed experiences 10° heel.
GB0804014A 2008-03-04 2008-03-04 Dual s-band and x-band active radar transponder Withdrawn GB2458123A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB0804014A GB2458123A (en) 2008-03-04 2008-03-04 Dual s-band and x-band active radar transponder
GB0903245A GB2457385A (en) 2008-03-04 2009-02-26 Dual s-band and x-band active radar transponder

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0804014A GB2458123A (en) 2008-03-04 2008-03-04 Dual s-band and x-band active radar transponder

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GB0804014D0 GB0804014D0 (en) 2008-04-09
GB2458123A true GB2458123A (en) 2009-09-09

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220260675A1 (en) * 2021-02-18 2022-08-18 The United States Of America, As Represented By The Secretary Of The Navy Ground based radar cross section measurement of countermeasures

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109669162A (en) * 2018-12-24 2019-04-23 中国电子科技集团公司第二十研究所 One kind being applied to S-X two waveband pathfinder receive-transmit system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2052908A (en) * 1979-05-23 1981-01-28 Secr Defence Radar transponders

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Publication number Priority date Publication date Assignee Title
SE419002B (en) * 1979-12-11 1981-07-06 Ericsson Telefon Ab L M PROCEDURE FOR IN A RADAR FIRE PREVENT THAT THE FOUR REPLIES TO THE RADAR PULS RECEIVED FROM A SIDARANT'S SIDOLOBER AND DEVICE FOR EXECUTING THE PROCEDURE
DE3218690C1 (en) * 1982-05-18 1986-07-17 Siemens AG, 1000 Berlin und 8000 München Biconical omnidirectional antenna
GB2265523A (en) * 1992-03-21 1993-09-29 Richard Morris Trim Radar transponder for echo enhancement
GB0212076D0 (en) * 2002-05-25 2002-07-03 Univ Birmingham Radar transponder

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Publication number Priority date Publication date Assignee Title
GB2052908A (en) * 1979-05-23 1981-01-28 Secr Defence Radar transponders

Non-Patent Citations (2)

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Title
MMIC Transmitter for a Commercial Search and Rescue Radar Transponder, IEEE Transactions on Microwave Theory, Vol.43, No.7, July 1995. *
Radar Reflectors, Jim Corenman, Chuck Hawley, Dick Honey and Stan Honey, www.ussailing.org.safety/Studies/radar-reflector-test.htm *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220260675A1 (en) * 2021-02-18 2022-08-18 The United States Of America, As Represented By The Secretary Of The Navy Ground based radar cross section measurement of countermeasures

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Publication number Publication date
GB2457385A (en) 2009-08-19
GB0903245D0 (en) 2009-04-08
GB0804014D0 (en) 2008-04-09

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