WO1992014277A1 - Antenne radar - Google Patents

Antenne radar Download PDF

Info

Publication number
WO1992014277A1
WO1992014277A1 PCT/AU1992/000039 AU9200039W WO9214277A1 WO 1992014277 A1 WO1992014277 A1 WO 1992014277A1 AU 9200039 W AU9200039 W AU 9200039W WO 9214277 A1 WO9214277 A1 WO 9214277A1
Authority
WO
WIPO (PCT)
Prior art keywords
radar antenna
radiating elements
antenna according
feed element
antenna
Prior art date
Application number
PCT/AU1992/000039
Other languages
English (en)
Inventor
Ian Kay Harvey
Original Assignee
Commonwealth Scientific And Industrial Research Organisation
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Commonwealth Scientific And Industrial Research Organisation filed Critical Commonwealth Scientific And Industrial Research Organisation
Publication of WO1992014277A1 publication Critical patent/WO1992014277A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/20—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/24—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave constituted by a dielectric or ferromagnetic rod or pipe

Definitions

  • the present invention relates to a radar device and in particular to a directional radar antenna for the transmission and reception of linearly polarised short electrical impulses, and a radar utilising such an antenna.
  • antennas for use in radars which provide high resolution ranging measurements over short distances have exhibited poor directional properties. That is, a transmitted signal is radiated over a wide angle, and a received signal can be received over substantially the same angle.
  • a directional radar antenna for transmitting and receiving linearly polarised short impulse waveforms, the antenna including a feed element terminating in a load and a plurality of co-planar spaced apart radiating elements connected with the feed element, the radiating elements being non-resonant for the highest significant frequency component of the impulse waveform.
  • the radiating elements are non-periodically spaced apart and this non-periodic spacing involves a linear taper to minimise undesirable spatial resonances in the line.
  • the use of other tapers or a randomised spacing can achieve the same purpose.
  • the radiating elements are linearly spaced.
  • the radiation pattern of the antenna is highly directive and has a maximum which is directed towards the load with a very low level of radiation in the reverse direction.
  • the maximum of the radiation pattern is slightly angularly displaced from the axis of the antenna.
  • this displacement is enhanced by immersion or part immersion of the antenna in a medium of higher dielectric constant. This characteristic may be used to advantage in certain applications (e.g. bore-hole radar) .
  • a long antenna of this type located on a dielectric surface and launching a wave at an angle into that surface to achieve both deep and close surface target detection.
  • this beam displacement may be compensated for or modified by changing the velocity of propagation of the antenna line by for example appropriate dielectric loading or by - A - otherwise changing the effective electrical length between the radiating elements or the timing of the impulsive excitation of each of the elements.
  • the beam displacement from the antenna axis may be made continuously or stepwise variable by mechanical or electronic means.
  • the antenna transmits and receives linearly polarised impulse waveforms.
  • a radar system including an impulse generator for supplying an impulse waveform to an antenna, the antenna terminating in a load and including a plurality of spaced apart radiating elements, the radiating elements being non-resonant for the highest significant frequency component of the waveform, and receiver means to receive signals reflected from a target and provide an indication of the distance to the target.
  • Figure 1 is a sectional side view of a directional antenna according to the invention.
  • Figure 2 is a sectional view taken from line 2-2 of Figure 1. MODES FOR CARRYING OUT THE INVENTION
  • radar antenna 1 transmits and receives impulse waveforms and includes a feed element 2 terminating in a load 3.
  • the feed element supplies the impulse waveform to a plurality of co-planar non-periodically spaced apart radiating elements 4.
  • the radiating elements are non-resonant for the highest significant frequency component of the impulse waveform.
  • the impulse waveforms generally range from several nanoseconds to the order of 100 picoseconds duration, the duration being selected to suit the particular ranging application and transmission medium.
  • the antenna is appropriately scaled for the chosen impulse duration.
  • the impulse waveforms used for example in very high resolution range measurements to detect electromagnetic discontinuities within materials or structures, generally include impulses of the order of 200 picosecond in duration, and repeated at a rate in the order of 100 MHz.
  • the radiated field emanating from the antenna has a maximum aligned at a small angle with the antenna transmission line towards the load with a beam width depending upon antenna length.
  • this antenna can utilise a variety of manufacturing methods for example, compact versions in printed circuit form. Such embodiments will facilitate ease of manufacture and use, for example, hand operable scanning across a surface. It will be appreciated that the dimensions of the antenna can be varied to suit the particular application and frequency range without removing it from the scope of the invention. Furthermore, the antenna can be either hand held or mounted in a known way. The received signals are processed by a receiver unit using known pulse sampling techniques.
  • nSec antenna 1 For transmitting impulses of the order of 1 nSec antenna 1 includes a feed element in the form of a 850 mm long 50 Ohm air dielectric transmission line 2 having an inner conductor 5 centrally located within a square metallic trough 6. An impulsive excitation applied at one end 8 of conductor 5 propagates along the length to be absorbed in a termination in the form of balanced load 3 at the far end 9.
  • line 2 radiating elements 4 each of length 30 mm which are attached to conductor 5 protrude from the open side of trough 6. The spacing of elements 4 varies in a linear fashion from 60 mm at the input end 8 of line 2 to 25 mm at the termination end 9.
  • the elements sequentially excited by the passage of the impulsive wave, produce a vertically polarised radiation pattern having a half power beam width of approximately 30 degrees with an inclination of 10 degrees to the antenna axis.
  • a small scale replica of this antenna for the transmission of impulses of 150 pSec duration has a length of 210 mm.
  • a further embodiment of the invention involves an array of two or more antennas as described above and supplying the respective antennas with impulse waveforms having appropriate delays and polarities. In this manner the shape and direction of the resultant radiation pattern can be varied according to the differential delays between the waveforms.
  • the radiating elements are periodically spaced apart.
  • an antenna according to the invention is able to be used in determining the depth of railway ballast over infiltrating subsoil, the position of liquid metal interfaces and the thickness of a blast furnace refactory lining.
  • the antenna enables in these applications the in situ measurement of quantities otherwise not obtainable without disabling or dismantling associated structures.

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  • Radar Systems Or Details Thereof (AREA)

Abstract

Une antenne radar directrice (1) émet et reçoit des formes d'ondes à impulsions et comprend un élément d'alimentation (2) se terminant par une charge (3). L'élément d'alimentation fournit la forme d'onde à impulsions à une multiplicité d'éléments à rayonnement (4) coplanaires espacés. Les éléments à rayonnement (4) sont du type non résonant en ce qui concerne la composante à fréquence significative la plus élevée de la forme d'ondes à impulsions. La durée des impulsions peut être comprise entre plusieurs nano secondes et cent pico secondes. L'antenne (1) est utilisée dans un système radar qui comprend aussi un générateur d'impulsions et un élément récepteur, afin de fournir une indication de la distance par rapport à une cible.
PCT/AU1992/000039 1991-01-31 1992-01-30 Antenne radar WO1992014277A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPK4401 1991-01-31
AUPK440191 1991-01-31

Publications (1)

Publication Number Publication Date
WO1992014277A1 true WO1992014277A1 (fr) 1992-08-20

Family

ID=3775201

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1992/000039 WO1992014277A1 (fr) 1991-01-31 1992-01-30 Antenne radar

Country Status (2)

Country Link
WO (1) WO1992014277A1 (fr)
ZA (2) ZA92712B (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU375746A (en) * 1946-05-23 1946-05-24 Western Electric Company, Incorporated Microwave radio transmission
US2408435A (en) * 1941-03-01 1946-10-01 Bell Telephone Labor Inc Pipe antenna and prism
US2624002A (en) * 1949-08-19 1952-12-30 Maurice G Bouix Dielectric antenna array
GB852322A (en) * 1955-10-21 1960-10-26 Kelvin & Hughes Ltd Improvements in and relating to linear array aerials
US4313120A (en) * 1979-07-30 1982-01-26 Ford Aerospace & Communications Corp. Non-dissipative load termination for travelling wave array antenna
US4518967A (en) * 1982-03-05 1985-05-21 Ford Aerospace & Communications Corporation Tapered-width leaky-waveguide antenna

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2408435A (en) * 1941-03-01 1946-10-01 Bell Telephone Labor Inc Pipe antenna and prism
AU375746A (en) * 1946-05-23 1946-05-24 Western Electric Company, Incorporated Microwave radio transmission
AU1013747A (en) * 1947-02-24 1947-03-20 Standard Telephones And Cables Pty. Limited Ultrahigh frequency antenna
US2624002A (en) * 1949-08-19 1952-12-30 Maurice G Bouix Dielectric antenna array
GB852322A (en) * 1955-10-21 1960-10-26 Kelvin & Hughes Ltd Improvements in and relating to linear array aerials
US4313120A (en) * 1979-07-30 1982-01-26 Ford Aerospace & Communications Corp. Non-dissipative load termination for travelling wave array antenna
US4518967A (en) * 1982-03-05 1985-05-21 Ford Aerospace & Communications Corporation Tapered-width leaky-waveguide antenna

Also Published As

Publication number Publication date
ZA92713B (en) 1993-01-27
ZA92712B (en) 1993-01-27

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