WO2009120237A1 - Receiver interference protection and direction finding antenna system - Google Patents

Receiver interference protection and direction finding antenna system Download PDF

Info

Publication number
WO2009120237A1
WO2009120237A1 PCT/US2008/081615 US2008081615W WO2009120237A1 WO 2009120237 A1 WO2009120237 A1 WO 2009120237A1 US 2008081615 W US2008081615 W US 2008081615W WO 2009120237 A1 WO2009120237 A1 WO 2009120237A1
Authority
WO
WIPO (PCT)
Prior art keywords
open circuited
passive
antennas
receiving antenna
passive open
Prior art date
Application number
PCT/US2008/081615
Other languages
French (fr)
Inventor
Stanley F. Williams
Original Assignee
Williams Stanley F
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 Williams Stanley F filed Critical Williams Stanley F
Priority to EP08873589A priority Critical patent/EP2274780A4/en
Publication of WO2009120237A1 publication Critical patent/WO2009120237A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/28—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using a secondary device in the form of two or more substantially straight conductive elements
    • H01Q19/30—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using a secondary device in the form of two or more substantially straight conductive elements the primary active element being centre-fed and substantially straight, e.g. Yagi antenna
    • 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
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
    • 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
    • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole

Definitions

  • the present invention is generally directed to an antenna system. More specifically, the present invention is directed to an antenna system which provides passive electromagnetic interference suppression or anti-jamming effects, as well as electromagnetic interference direction finding, and method for suppressing, resisting, or reducing electromagnetic interference and for locating a direction of an interfering signal source.
  • Radio frequency (RF) jamming i.e., intentional or unintentional RF interference, occurs when RF power is transmitted so as to interfere with the reception and interpretation of an RF receiving system and in some cases permanently damage the electronics within the receiving antenna unit or system.
  • Jamming signals may interfere with or terminate the operation of receivers specifically satellite receivers such as navigation, communication, and global navigation satellite system (GNSS), such as global positioning system (GPS) receivers. In this sense, electromagnetic interference
  • EMI generally, and jamming in particular, is considered countermeasures to the intended utilization of RF antenna-receiver systems .
  • the present invention is directed to a passive system for determining the location of an interfering signal and for minimizing the effects of EMI in RF systems.
  • This invention employs an external array of passive open circuited antennas strategically arranged close to an intended receiving antenna unit or system. Each passive antenna is not electrically connected to an intended receiving antenna unit or system, other than via an electrical ground, so as to be open circuited relative to the intended receiving antenna unit or system.
  • the array of passive open circuited antennas disrupts intentional or unintentional interference signals and reduces the electromagnetic energy, interference, and noise reaching the intended receiving antenna unit or system, as well as assist in identifying a direction of an interfering signal source.
  • the present invention is more simple, efficient, and cost effective than conventional electromagnetic interference direction finding and anti-jamming systems.
  • the present system can also include remote control adjustment capability using servo step motors, computers, and computer software to adjust passive open circuited antenna positions, passive open circuited antenna element heights, intended antenna-receiver height, rotation of a passive open circuited antenna array, and tilt angles of a passive open circuited antenna all to achieve best mode of operation and performance.
  • the system can also utilize automatic signal strength and bit error rate (BER) detection algorisms to automatically sense poor values and make various automatic adjustments to passive open circuited antenna positions, passive open circuited antenna element height, intended receiving antenna unit or system height, and antenna system base rotation to obtain straightest possible angle of incidence for the direction of the incoming undesired EMI signal to the intended receiving antenna unit or system to enhance operation, performance, and interference signal reduction and suppression while simultaneously identifying a direction of an interfering signal source.
  • BER bit error rate
  • the present invention likewise utilizes a method for electromagnetic interference direction finding and interference suppression, resistance, reduction, and potential antenna electronics damage of an existing RF antenna-receiver system by passively disrupting the interfering signal path to an Intended receiving antenna unit or system.
  • the present method passively mitigates the impact of the intentional or unintentional RF jamming and interference before reaching the intended receiving antenna unit or system, while simultaneously determining a location of an interfering signal source.
  • system and method of the invention can be combined with other external and/or internal antenna system designs, and direction finding and interference mitigation methods, such as RF filters, adaptive antenna system countermeasure techniques referred to as controlled reception pattern antenna (CRPA) array systems or fixed reception pattern antenna (FRPA) array systems, and passive prescreening of the RF energy incident upon a receiving antenna unit or system, as described in US patent no. 6,992,643, any combination of which could result in even greater direction finding capabilities and/or interference suppression or resistance .
  • RF filters such as controlled reception pattern antenna (CRPA) array systems or fixed reception pattern antenna (FRPA) array systems
  • FRPA fixed reception pattern antenna
  • FIG. 1 shows a passive open circuited antenna and electrical connections for a passive open circuited antenna center conductor and outer shield for use with the present invention
  • FIG. 2 shows a passive open circuited antenna and a magnetic mounting bracket for the passive antenna for use with the present invention
  • FIG. 3 shows a passive open circuited antenna and a permanent or hard mounting arrangement for mounting the passive open circuited antenna to a ground or surface plane;
  • FIG. 4 shows a permanent or hard mounting arrangement for two passive open circuited antennas at a specified distance and angle from the intended receiving antenna unit or system;
  • FIG. 5 shows a direction finding and anti-jamming system utilizing two passive open circuited antennas placed close together and directly between an interfering signal source and an intended receiving antenna unit or system to form a triangle in accordance with the present invention
  • FIG. 6 shows a direction finding anti-jamming system utilizing three passive open circuited antennas placed close together and directly between an interfering signal source and an intended receiving antenna unit or system wherein the three passive open circuited antennas form a triangle having a base facing the intended receiving antenna unit or system and an vertex facing the interfering signal in accordance with a preferred embodiment of the present invention
  • Fig. 7 shows a direction finding and anti-jamming system utilizing four passive open circuited antennas placed close together and directly between an interfering signal source and an intended receiving antenna unit or system wherein two passive open circuited antennas form a triangle with the intended receiving antenna unit or system and the other passive open circuited antenna form triangles between each other and are in generally parallel lines in accordance with an alternative embodiment of the present invention
  • Fig. 8 shows a direction finding and anti-jamming system utilizing passive open circuited antennas surrounding an intended receiving antenna unit or system such that the passive open circuited antennas form triangles with the intended receiving antenna unit or system in accordance with an alternative embodiment of the present invention
  • FIG. 9 shows a direction finding and anti-jamming system utilizing multiple passive open circuited antennas wherein some passive open circuited antennas surround an intended receiving unit or system such that the passive open circuited antennas form triangles with the intended receiving antenna unit and other passive open circuited antennas form generally parallel lines between the intended receiving unit or system and an interfering signal source in accordance with another embodiment of the present invention
  • FIG. 10 is a top view of passive open circuited antennas mounted to adjustable slide brackets which are mounted to a common mounting base to allow the passive open circuited antennas to be adjusted relative to each other and to an intended receiving antenna unit or system in accordance with the present invention
  • Fig. 11 is a side view of the mounted passive open circuited antennas shown in Fig. 10;
  • Fig, 12 shows a direction finding and anti-j amming system utilizing multiple passive open circuited antennas surrounding an intended receiving antenna unit or system such that the passive open circuited antennas form triangles among the passive antennas in accordance with another embodiment of the present invention.
  • Fig. 13 shows a direction finding and anti-j amming system utilizing multiple passive open circuited antennas wherein some passive open circuited antennas surround an intended receiving unit or system such that the passive open circuited antennas form triangles among the passive antennas and other passive open circuited antennas form generally parallel lines between the intended receiving unit or system and an interfering signal source in accordance with another alternative embodiment of the present invention.
  • the present invention is directed to a system and method for electromagnetic interference direction finding and for improving EMI suppression, resistance, reduction, or potential antenna electronics damage of an antenna-receiver system through an arrangement of passive open circuited antennas surrounding an intended receiving antenna unit or system that is to be protected.
  • the system and method involve utilizing an array of passive open circuited antennas placed close to an intended receiving antenna unit or system so that the passive open circuited antennas disrupt an incoming interference signal.
  • Each passive open circuited antenna is not in electrical connection with an intended receiving antenna unit or system, other than via an electric ground, so that the antenna is open circuited relative to the intended receiving antenna unit or system.
  • a direction of an interfering signal can be determined by extending a continuous straight line from the intended receiving antenna unit or system through the array of passive open circuited antennas.
  • the passive open circuited antennas assist in determining a location of an interfering signal source and reduce the electromagnetic energy, interference, and noise received by the intended receiving antenna unit or system.
  • the present invention results in an increase in desired signal quality and signal strength where the original undisturbed or interference free desired signal is weak (e.g. satellite signals) .
  • the original undisturbed or interference free desired signal is weak (e.g. satellite signals) .
  • the original undisturbed satellite signal is partially restored and an increase in satellite signal is achieved.
  • FIG. 1 shows one possible type of passive open circuited antenna 20 for use with the present direction finding and anti-jamming system and method.
  • the antenna includes an outer plastic jacket 28, electrical connections 50 and 60, a center conductor 30, and an outer shield 40.
  • any suitable type of passive open circuited antenna or passive system may be used, such as helix, di-pole, rod, whip, stubby, Hertz, or Marconi antennas.
  • FIG. 2 shows the passive open circuited antenna 20 attached to a magnetic mounting bracket base 110 having an Incased magnet 108.
  • the magnetic mounting bracket 110 allows the passive open circuited antenna 20 to be easily moved around an intended receiving antenna unit or system 10 that may be installed on steel or similar surface ground plane material 13 to identify and achieve best location and performance for EMI reduction or suppression.
  • the magnet 108 also improves the performance of the direction finding and anti-jamming system.
  • the direction finding and anti-jamming system and method may use a permanent or hard mounting arrangement for securing each passive open circuited antenna 20.
  • FIG. 3 shows the passive open circuited antenna 20 of length 80, mounted to permanent or hard mounting arrangement bracket 120 at an attachment point 70. The antenna 20 is secured to the bracket 120 by mounting hardware 130 and 140.
  • any suitable mounting arrangement or mounting hardware may be used.
  • FIG. 4 Another mounting arrangement for securing passive open circuited antennas 20 and 24 is shown in FIG. 4.
  • the passive open circuited antennas 20 and 24 are attached to permanent or hard mounting brackets 120 and 124 and mounting bracket hardware 140 and 144, respectively, to the ground plane level 13.
  • the intended receiving antenna unit or system 10 is attached to an adjustable slide pole 12 located between the passive open circuited antennas 20 and 24.
  • the intended receiving antenna unit or system is spaced a distance 11 from the ground plane level 13.
  • the distance 11 is greater than or equal to the distance between a bottom of each of the passive open circuited antennas 20 and 24 and the ground plane level 13.
  • the antennas are preferably positioned between interfering signals 6 and the intended receiving antenna unit or system 10.
  • the antennas 20 and 24 are positioned so that centers of the antennas 20 and 24 are spaced distances 90 and 94, respectively, from a center of the intended receiving antenna unit or system 10.
  • the antennas 20 and 24 are also tilted toward the interfering signals 6 at tilt angles 180 and 184, respectively, relative to a ground plane level 13.
  • FIG. 5 One direction finding and anti-jamming system for identifying a location of an interfering signal source while suppressing, resisting, or reducing intentional or unintentional RF jamming and interference energy 6 is depicted in FIG. 5.
  • the system includes two passive open circuited antennas 20 and 21 placed directly between an interference signal source 5 and an intended receiving antenna unit or system 10.
  • the passive antennas 20 and 21 are not electrically connected to the intended receiving antenna unit or system 10, other than via an electric ground, which is not shown in FIG. 5, so that the antennas 20 and 21 are open circuited with respect to the intended receiving antenna unit or system 10. Further, depending on the type of antenna, each passive open circuited antenna may be connected to a ground or surface plane.
  • the passive antennas 20 and 21 are positioned so that centers of the antennas 20 and 21 are spaced distances 90 and 91, respectively, from a center of the intended receiving unit or system 10 so as to form a triangle with the receiving unit or system 10.
  • the arrangement of the passive open circuited antennas 20 and 21 and the intended receiving antenna unit or system 10 forms an isosceles triangle, but any suitable configuration may be used.
  • the system determines the location of the interference signal source 5, as well as provides enhanced reduction or suppression of the interference energy 6.
  • the system also identifies the location of interference signal sources 3 and 4 and suppresses or reduces interfering signal energies 7 and 8. As the angles of incident for the interference signals increases either horizontally or vertically relative to the passive open circuited antennas 20 and 21, the direction finding and EMI reduction or suppression capability gained from the passive antennas 20 and 21 may decrease.
  • FIG. 6 A preferred embodiment of the direction finding and anti-jamming system of the present invention is shown in FIG. 6.
  • the system employs three passive open circuited antennas 20, 21, and 22 placed between an interference signal source 5 and the Intended receiving antenna unit or system 10.
  • the passive antennas 20, 21, and 22 are not electrically connected to the intended receiving antenna unit or system 10, other than via an electric ground, which is not shown in FIG. 6, so that the antennas 20, 21, and 22 are open circuited with respect to the intended receiving antenna unit or system 10.
  • each passive open circuited antenna may be connected to a ground or surface plane.
  • this system uses three passive open circuited antennas, any number of passive sources may be used.
  • the passive antennas 20 and 21 are positioned so that centers of the antennas 20 and 21 are spaced distances 90 and 91, respectively, from a center of the intended receiving unit or system 10 so as to form a triangle with the receiving unit or system 10.
  • the arrangement of the passive open circuited antennas 20 and 21 and the intended receiving antenna unit or system 10 forms an isosceles triangle, but any suitable configuration may be used.
  • the antennas 20, 21, and 22 also form a triangle, preferably an isosceles triangle, and the centers of the passive antennas 20, 21, and 22 are spaced distances, 100, 101, and 102 relative to each other. As shown in FIG.
  • passive open circuited antennas 20 and 21 form a base of the triangle, and the base faces the intended receiving unit or system 10.
  • Passive open circuited antenna 22 is positioned opposite the base formed by passive open circuited antennas 20 and 21 to form a vertex of the triangle, and the vertex faces an interfering signal source 5.
  • the system provides optimal reduction or suppression of the interference energy 6, as well as the most accurate identification of the direction of the interference energy 6. Specifically, since the direction of an interfering signal 6 forms a continuous straight line from the intended receiving unit or system 10 through the array of passive open circuited antennas 20, 21, and 22 to the interfering signal source 5, the intended receiving unit or system 10 performance is optimal.
  • the system also identifies the location of interference sources 3 and 4 and provides some suppression or reduction of interfering signal energies 7 and 8.
  • An alternative embodiment of the present direction finding and anti-jamming system for use with severe intentional or unintentional RF jamming is shown in FIG 7.
  • the system employs four passive open circuited antennas 20, 21, 22, and 23 placed directly between an interference signal source 5 of severe interfering signal 6 and the intended receiving antenna unit or system 10.
  • each passive open circuited antenna may be connected to a ground or surface plane. While this system uses four passive open circuited antennas, any number of passive sources may be used.
  • the passive antennas 20 and 21 are positioned so that centers of the antennas 20 and 21 are spaced distances 90 and 91, respectively, from a center of the intended receiving unit or system 10 so as to form a triangle with the receiving unit or system 10.
  • the arrangement of the passive open circuited antennas 20 and 21 and the intended receiving antenna unit or system 10 forms an isosceles triangle, but any suitable configuration may be used.
  • the antennas 20, 21, 22, and 23 are also placed so that the centers of the passive antennas 20, 21, 22, and 23 are spaced distances, 101, 102, 108, and 109, relative to each other. As shown in FIG.
  • passive open circuited antennas 20 and 21 are placed in a row generally parallel to a row containing passive antennas 22 and 23. Further, passive antennas 20 and 22 are positioned in a row substantially parallel to a row containing antennas 21 and 23. In addition, the antennas 20, 21, 22, and 23 are positioned to form two triangles, which are preferably equilateral triangles .
  • the system Since the passive antennas 20, 21, 22, and 23 are placed between interference source 5 of the interfering signal 6 and the intended receiving unit or system 10, the system provides optimal reduction or suppression of the interference energy 6. Further, even though the passive open circuit antennas 20, 21, 22, and 23 are not placed directly between the intended receiving antenna unit or system 10 and interference sources 3 and 4 or interference signals 7 and 8, respectively, but rather are placed at angles relative to the intended receiving unit or system 10, the system also identifies the location of interference sources 3 and 4 and provides some suppression or reduction of interfering signal energies 7 and 8.
  • FIG 8. Another embodiment of a direction finding and anti ⁇ jamming system is shown in FIG 8.
  • This system employs multiple passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, and 27 surrounding the intended receiving antenna unit or system 10.
  • the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are not electrically connected to the intended receiving antenna unit or system 10, other than via an electric ground, which is not shown in FIG. 8, so that the antennas 20, 21, 22,
  • each passive open circuited antenna may be connected to a ground or surface plane.
  • the antennas 20, 21, 22, 23, 24, 25, 26, and 27 are placed so that the centers of the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are spaced distances 90, 91, 92, 93, 94, 95, 96, and 97, respectively, from a center of the intended receiving unit or system 10.
  • the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are also positioned at distances 100, 101, 102, 103, 104, 105, 106, and 107 relative to each other, as shown in FIG. 8.
  • the passive open circuited antennas are positioned 20, 21, 22, 23, 24, 25, 26, and 27 are positioned around the intended receiving unit or system 10 so as to form triangles with the intended receiving unit or system 10.
  • passive open circuited antennas 20 and 21 form a triangle with the intended receiving unit or system 10 with sides with lengths corresponding to the distances 90, 91, and 100, as shown in Fig. 8.
  • FIG. 9 A further embodiment of a direction finding and anti-jamming system is shown in FIG. 9. Similar to the system depicted in FIG. 8, this system also utilizes multiple passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, and 27 surrounding the intended receiving antenna unit or system 10.
  • the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are placed so that the centers of the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are spaced distances 90, 91, 92, 93, 94, 95, 96, and 97, respectively, from a center of the intended receiving unit or system 10.
  • the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are also positioned at distances 100, 101, 102, 103, 104, 105, 106, and 107 relative to each other, as shown in FIG. 9. Further, the passive open circuited antennas are positioned 20, 21, 22, 23, 24, 25, 26, and 27 are positioned around the intended receiving unit or system 10 so as to form triangles with the intended receiving unit or system 10.
  • This system also includes an additional parallel array of passive open circuited antennas N 1 ⁇ N 2 , N 3 , N 4 , N 5 , N 6 , and N n + L which represent a continuing line of passive open circuited antennas for protecting the intended receiving antenna unit 10 in cases of "severe" EMI.
  • These passive antennas N lf N 2 , N 3 , N 4 , N 5 , N 6 , and N n + ! are separated by distances M 1 r M 2j M 3 ⁇ M 4/ M 5/ M 6; M 7, M 8r M 9r and M m+lr creating parallel lines and triangles among passive open circuited antennas, as shown in FIG. 9.
  • Passive open circuited antennas can be mounted to adjustable slide brackets which are mounted to a common mounting base to allow the open circuited antennas to be adjusted relative to each other and to the intended receiving antenna unit or system 10.
  • a location finding and anti-jamming system utilizing three passive open circuited antennas mounted to adjustable slide brackets is depicted in FIGS. 10 and 11. While this system uses three passive open circuited antennas, any number of antennas can be used. For example, multiple passive open circuited antennas can be arranged in groups of three around the intended receiving unit 10, and each group of three passive open circuited antennas can be mounted to an adjustable slide bracket.
  • the intended receiving antenna unit or system 10 is mounted to an adjustable slide pole 12 so that a height of the intended receiving antenna unit or system 10 relative to the passive open circuited antennas 20, 21, and 22 may be adjusted.
  • the passive open circuited antennas 20, 21, and 22 are mounted to a slide bracket 150.
  • Each of the passive open circuited antennas 20, 21, and 22 are received in a slot 161 in the slide bracket 150 so that the passive open circuited antennas 20, 21, and 22 may slide within the slots 161 and move distances 171.
  • the slide bracket 150 may be connected to a servo step motor or other suitable moving means to move the passive open circuited antennas 20, 21, and 22 along the slots 161.
  • the slide bracket 150 is moveably mounted to a mounting base 190. Specifically, the slide bracket 150 is received in a slot 160 of the mounting base 190 so that the bracket 150 can slide within the slot 160 and move a distance 170.
  • the mounting base 190 is also connected to a servo step motor 210 so that the base 190 can move 360° along a circular path 200 around the intended receiving unit 210. While a servo step motor 210 is preferred, any suitable driving means for moving the mounting base 190 around the intending receiving unit 10 may be used.
  • the height of the intended receiving antenna unit or system 10 may be adjusted based on an angle of incidence and direction of an interference signal.
  • the position of the passive open circuited antennas 20, 21, and 22 relative to the intended receiving unit 10 can also be modified via the adjustable slide bracket mounting base 150 to optimize EMI and noise suppression or reduction and more accurately detect the location of an interfering signal source .
  • the following parameters may also be adjusted: a polarity match between the passive open circuited antennas and the interfering signal source, the height of the intended receiving antenna unit or system in relationship to the passive open circuited antennas, the number and physical arrangement of passive open circuited antennas surrounding the intended receiving antenna unit or system, the type of passive open circuited antennas used, the physical or electrical length of the passive open circuited antenna elements, the tilt angles of the passive open circuited antennas in the direction of the interfering signal, the distance between passive open circuited antennas and the intended receiving antenna unit or system, the distance between each passive open circuited antenna, the power density of the electromagnetic field, and angle of incidence and direction of the incoming undesired electromagnetic interference signal.
  • the passive open circuited antennas are preferably placed in groups of three around an intended receiving unit or system 10.
  • An embodiment of a direction finding and anti-jamming system of the present invention utilizing a plurality of open circuited antennas placed in groups of three about an intended receiving unit or system 10 is shown in FIG 12.
  • This system employs multiple passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, 27, 205, 225, 245, and 265 surrounding the intended receiving antenna unit or system 10.
  • the passive antennas 20, 21, 22, 23, 24, 25, 26, 27, 205, 225, 245, and 265 are not electrically connected to the intended receiving antenna unit or system 10, other than via an electric ground, which is not shown in FIG.
  • each passive open circuited antenna may be connected to a ground or surface plane.
  • the antennas 20, 21, 22, 23, 24 r 25, 26, and 27 are placed so that the centers of the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are spaced distances 90, 91, 92, 93, 94, 95, 96, and 97, respectively, from a center of the intended receiving unit or system 10.
  • the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are also positioned at distances 100, 101, 102, 103, 104, 105, 106, and 107 relative to each other, as shown in FIG. 12.
  • the passive open circuited antennas are positioned 20, 21, 22, 23, 24, 25, 26, and 27 are positioned around the intended receiving unit or system 10 so as to form triangles with the intended receiving unit or system 10.
  • passive open circuited antennas 20 and 21 form a triangle with the intended receiving unit or system 10 having lengths 90, 91, and 100.
  • the passive open circuited antennas 205, 225, 245, and 265 also surround the intended receiving unit or system 10 and are placed at distances 200, 210, 220, 230, 240, 250, 260, and 270, respectively, from the passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, and 27.
  • the passive open circuited antennas 205, 225, 245, and 265 are positioned to form triangles with the passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, and 27 between the intended receiving unit or system 10 and an interfering signal source.
  • passive open circuited antennas 20, 21, and 205 form a triangle having lengths 200, 210, and 100.
  • This system also utilizes multiple passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, 27, 225, 245, and 265 surrounding the intended receiving antenna unit or system 10.
  • the antennas 20, 21, 22, 23, 24, 25, 26, and 27 are placed so that the centers of the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are spaced distances 90, 91, 92, 93, 94, 95, 96, and 97, respectively, from a center of the intended receiving unit or system 10.
  • the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are also positioned at distances 100, 101, 102, 103, 104, 105, 106, and 107 relative to each other, as shown in FIG. 12.
  • the passive open circuited antennas are positioned 20, 21, 22, 23, 24, 25, 26, and 27 are positioned around the intended receiving unit or system 10 so as to form triangles with the intended receiving unit or system 10.
  • the passive open circuited antennas 225, 245, and 265 also surround the intended receiving unit or system 10 and are placed at distances 220, 230, 240, 250, 260, and 270, respectively, from the passive open circuited antennas 22, 23, 24, 25, 26, and 27.
  • the passive open circuited antennas 225, 245, and 265 are positioned to form triangles with the passive open circuited antennas 22, 23, 24, 25, 26, and 27 between the intended receiving unit or system 10 and an interfering signal source.
  • passive open circuited antennas 22, 23, and 225 form a triangle having lengths 220, 230, and 102, as shown in Fig. 13.
  • This system also includes an additional parallel array of passive open circuited antennas N 1 , N 2 , N 3 , N 4 , N 5 , N 6 , and N n + ⁇ which represent a continuing line of passive open circuited antennas for protecting the intended receiving antenna unit 10 in cases of "severe" EMI.
  • These passive antennas N 1, N 2 , N 3 , N 4 , N 5 , N 6 , and N n + ! are separated by distances M 1, M 2, M 3, M 4 , M 5j M 6 , M 7 , M 8, M 9, and M m+1, creating parallel lines and triangles among passive open circuited antennas, as shown in FIG. 13.

Landscapes

  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)

Abstract

A tunable passive direction finding and anti-jamming antenna array system and method for determining a location of an electromagnetic interference signal source while minimizing the effects of electromagnetic interference in radio frequency antenna systems. The system and method utilize an external array of passive open circuited antennas strategically arranged between an intended receiving antenna unit or system and interfering signals to disrupt the interference signals and reduce the electromagnetic energy, interference, and noise reaching the intended receiving antenna unit or system, as well as determine the direction of an interference signal.

Description

RECEIVER INTERFERENCE PROTECTION AND DIRECTION FINDING
ANTENNA SYSTEM
FIELD OF THE INVENTION The present invention is generally directed to an antenna system. More specifically, the present invention is directed to an antenna system which provides passive electromagnetic interference suppression or anti-jamming effects, as well as electromagnetic interference direction finding, and method for suppressing, resisting, or reducing electromagnetic interference and for locating a direction of an interfering signal source.
BACKGROUND Radio frequency (RF) jamming, i.e., intentional or unintentional RF interference, occurs when RF power is transmitted so as to interfere with the reception and interpretation of an RF receiving system and in some cases permanently damage the electronics within the receiving antenna unit or system. Jamming signals may interfere with or terminate the operation of receivers specifically satellite receivers such as navigation, communication, and global navigation satellite system (GNSS), such as global positioning system (GPS) receivers. In this sense, electromagnetic interference
(EMI) generally, and jamming in particular, is considered countermeasures to the intended utilization of RF antenna-receiver systems .
A number of technigues have been developed to determine a location of interfering signal source and to mitigate the deleterious effects of EMI on RF antenna- receiver systems . These techniques typically employ additional internal antenna hardware components some having mathematically based software programs to minimize EMI. As a result of the additional hardware and software required by the conventional electromagnetic interference direction finding and anti-jamming systems, the conventional systems are costly and complex to develop and operate. Thus, there is a need for a more simplistic, cost-effective, and efficient system for mitigating the effects of EMI on RF antenna-receiver systems, while locating an interfering signal source.
SUMMARY
The present invention is directed to a passive system for determining the location of an interfering signal and for minimizing the effects of EMI in RF systems. This invention employs an external array of passive open circuited antennas strategically arranged close to an intended receiving antenna unit or system. Each passive antenna is not electrically connected to an intended receiving antenna unit or system, other than via an electrical ground, so as to be open circuited relative to the intended receiving antenna unit or system. The array of passive open circuited antennas disrupts intentional or unintentional interference signals and reduces the electromagnetic energy, interference, and noise reaching the intended receiving antenna unit or system, as well as assist in identifying a direction of an interfering signal source. As a result of the use of passive antennas to mitigate EMI, the present invention is more simple, efficient, and cost effective than conventional electromagnetic interference direction finding and anti-jamming systems.
The present system can also include remote control adjustment capability using servo step motors, computers, and computer software to adjust passive open circuited antenna positions, passive open circuited antenna element heights, intended antenna-receiver height, rotation of a passive open circuited antenna array, and tilt angles of a passive open circuited antenna all to achieve best mode of operation and performance. The system can also utilize automatic signal strength and bit error rate (BER) detection algorisms to automatically sense poor values and make various automatic adjustments to passive open circuited antenna positions, passive open circuited antenna element height, intended receiving antenna unit or system height, and antenna system base rotation to obtain straightest possible angle of incidence for the direction of the incoming undesired EMI signal to the intended receiving antenna unit or system to enhance operation, performance, and interference signal reduction and suppression while simultaneously identifying a direction of an interfering signal source.
The present invention likewise utilizes a method for electromagnetic interference direction finding and interference suppression, resistance, reduction, and potential antenna electronics damage of an existing RF antenna-receiver system by passively disrupting the interfering signal path to an Intended receiving antenna unit or system. In this way, the present method passively mitigates the impact of the intentional or unintentional RF jamming and interference before reaching the intended receiving antenna unit or system, while simultaneously determining a location of an interfering signal source.
Further, the system and method of the invention can be combined with other external and/or internal antenna system designs, and direction finding and interference mitigation methods, such as RF filters, adaptive antenna system countermeasure techniques referred to as controlled reception pattern antenna (CRPA) array systems or fixed reception pattern antenna (FRPA) array systems, and passive prescreening of the RF energy incident upon a receiving antenna unit or system, as described in US patent no. 6,992,643, any combination of which could result in even greater direction finding capabilities and/or interference suppression or resistance .
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the invention will be had with reference to the attached drawings wherein:
FIG. 1 shows a passive open circuited antenna and electrical connections for a passive open circuited antenna center conductor and outer shield for use with the present invention;
FIG. 2 shows a passive open circuited antenna and a magnetic mounting bracket for the passive antenna for use with the present invention; FIG. 3 shows a passive open circuited antenna and a permanent or hard mounting arrangement for mounting the passive open circuited antenna to a ground or surface plane;
FIG. 4 shows a permanent or hard mounting arrangement for two passive open circuited antennas at a specified distance and angle from the intended receiving antenna unit or system;
FIG. 5 shows a direction finding and anti-jamming system utilizing two passive open circuited antennas placed close together and directly between an interfering signal source and an intended receiving antenna unit or system to form a triangle in accordance with the present invention;
FIG. 6 shows a direction finding anti-jamming system utilizing three passive open circuited antennas placed close together and directly between an interfering signal source and an intended receiving antenna unit or system wherein the three passive open circuited antennas form a triangle having a base facing the intended receiving antenna unit or system and an vertex facing the interfering signal in accordance with a preferred embodiment of the present invention;
Fig. 7 shows a direction finding and anti-jamming system utilizing four passive open circuited antennas placed close together and directly between an interfering signal source and an intended receiving antenna unit or system wherein two passive open circuited antennas form a triangle with the intended receiving antenna unit or system and the other passive open circuited antenna form triangles between each other and are in generally parallel lines in accordance with an alternative embodiment of the present invention;
Fig. 8 shows a direction finding and anti-jamming system utilizing passive open circuited antennas surrounding an intended receiving antenna unit or system such that the passive open circuited antennas form triangles with the intended receiving antenna unit or system in accordance with an alternative embodiment of the present invention;
FIG. 9 shows a direction finding and anti-jamming system utilizing multiple passive open circuited antennas wherein some passive open circuited antennas surround an intended receiving unit or system such that the passive open circuited antennas form triangles with the intended receiving antenna unit and other passive open circuited antennas form generally parallel lines between the intended receiving unit or system and an interfering signal source in accordance with another embodiment of the present invention;
FIG. 10 is a top view of passive open circuited antennas mounted to adjustable slide brackets which are mounted to a common mounting base to allow the passive open circuited antennas to be adjusted relative to each other and to an intended receiving antenna unit or system in accordance with the present invention; and Fig. 11 is a side view of the mounted passive open circuited antennas shown in Fig. 10;
Fig, 12 shows a direction finding and anti-j amming system utilizing multiple passive open circuited antennas surrounding an intended receiving antenna unit or system such that the passive open circuited antennas form triangles among the passive antennas in accordance with another embodiment of the present invention; and
Fig. 13 shows a direction finding and anti-j amming system utilizing multiple passive open circuited antennas wherein some passive open circuited antennas surround an intended receiving unit or system such that the passive open circuited antennas form triangles among the passive antennas and other passive open circuited antennas form generally parallel lines between the intended receiving unit or system and an interfering signal source in accordance with another alternative embodiment of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
The present invention is directed to a system and method for electromagnetic interference direction finding and for improving EMI suppression, resistance, reduction, or potential antenna electronics damage of an antenna-receiver system through an arrangement of passive open circuited antennas surrounding an intended receiving antenna unit or system that is to be protected. The system and method involve utilizing an array of passive open circuited antennas placed close to an intended receiving antenna unit or system so that the passive open circuited antennas disrupt an incoming interference signal. Each passive open circuited antenna is not in electrical connection with an intended receiving antenna unit or system, other than via an electric ground, so that the antenna is open circuited relative to the intended receiving antenna unit or system. At a location where maximum interference signal disruption occurs, a direction of an interfering signal can be determined by extending a continuous straight line from the intended receiving antenna unit or system through the array of passive open circuited antennas. As a result, the passive open circuited antennas assist in determining a location of an interfering signal source and reduce the electromagnetic energy, interference, and noise received by the intended receiving antenna unit or system.
In addition to direction finding and reducing EMI and noise reduction, the present invention results in an increase in desired signal quality and signal strength where the original undisturbed or interference free desired signal is weak (e.g. satellite signals) . In other words, by reducing the EMI and noise in the frequency band of the intended receive signal, the original undisturbed satellite signal is partially restored and an increase in satellite signal is achieved.
FIG. 1 shows one possible type of passive open circuited antenna 20 for use with the present direction finding and anti-jamming system and method. The antenna includes an outer plastic jacket 28, electrical connections 50 and 60, a center conductor 30, and an outer shield 40. However, any suitable type of passive open circuited antenna or passive system may be used, such as helix, di-pole, rod, whip, stubby, Hertz, or Marconi antennas.
FIG. 2 shows the passive open circuited antenna 20 attached to a magnetic mounting bracket base 110 having an Incased magnet 108. The magnetic mounting bracket 110 allows the passive open circuited antenna 20 to be easily moved around an intended receiving antenna unit or system 10 that may be installed on steel or similar surface ground plane material 13 to identify and achieve best location and performance for EMI reduction or suppression. The magnet 108 also improves the performance of the direction finding and anti-jamming system.
As an alternative or in addition to the moveable mounting arrangement shown in FIG. 2, the direction finding and anti-jamming system and method may use a permanent or hard mounting arrangement for securing each passive open circuited antenna 20. FIG. 3 shows the passive open circuited antenna 20 of length 80, mounted to permanent or hard mounting arrangement bracket 120 at an attachment point 70. The antenna 20 is secured to the bracket 120 by mounting hardware 130 and 140. As an alternative or in addition to the depicted permanent bracket 120, any suitable mounting arrangement or mounting hardware may be used. Another mounting arrangement for securing passive open circuited antennas 20 and 24 is shown in FIG. 4. The passive open circuited antennas 20 and 24 are attached to permanent or hard mounting brackets 120 and 124 and mounting bracket hardware 140 and 144, respectively, to the ground plane level 13. The intended receiving antenna unit or system 10 is attached to an adjustable slide pole 12 located between the passive open circuited antennas 20 and 24. The intended receiving antenna unit or system is spaced a distance 11 from the ground plane level 13. Preferably, the distance 11 is greater than or equal to the distance between a bottom of each of the passive open circuited antennas 20 and 24 and the ground plane level 13.
The antennas are preferably positioned between interfering signals 6 and the intended receiving antenna unit or system 10. Specifically, the antennas 20 and 24 are positioned so that centers of the antennas 20 and 24 are spaced distances 90 and 94, respectively, from a center of the intended receiving antenna unit or system 10. The antennas 20 and 24 are also tilted toward the interfering signals 6 at tilt angles 180 and 184, respectively, relative to a ground plane level 13.
One direction finding and anti-jamming system for identifying a location of an interfering signal source while suppressing, resisting, or reducing intentional or unintentional RF jamming and interference energy 6 is depicted in FIG. 5. The system includes two passive open circuited antennas 20 and 21 placed directly between an interference signal source 5 and an intended receiving antenna unit or system 10. The passive antennas 20 and 21 are not electrically connected to the intended receiving antenna unit or system 10, other than via an electric ground, which is not shown in FIG. 5, so that the antennas 20 and 21 are open circuited with respect to the intended receiving antenna unit or system 10. Further, depending on the type of antenna, each passive open circuited antenna may be connected to a ground or surface plane. The passive antennas 20 and 21 are positioned so that centers of the antennas 20 and 21 are spaced distances 90 and 91, respectively, from a center of the intended receiving unit or system 10 so as to form a triangle with the receiving unit or system 10. Preferably, the arrangement of the passive open circuited antennas 20 and 21 and the intended receiving antenna unit or system 10 forms an isosceles triangle, but any suitable configuration may be used. In this arrangement, the system determines the location of the interference signal source 5, as well as provides enhanced reduction or suppression of the interference energy 6.
Further, even though the passive open circuit antennas 20 and 21 are not placed directly between the intended receiving antenna unit or system 10 and interference sources 3 and 4, but rather are placed at angles relative to the intended receiving unit 10, the system also identifies the location of interference signal sources 3 and 4 and suppresses or reduces interfering signal energies 7 and 8. As the angles of incident for the interference signals increases either horizontally or vertically relative to the passive open circuited antennas 20 and 21, the direction finding and EMI reduction or suppression capability gained from the passive antennas 20 and 21 may decrease.
A preferred embodiment of the direction finding and anti-jamming system of the present invention is shown in FIG. 6. The system employs three passive open circuited antennas 20, 21, and 22 placed between an interference signal source 5 and the Intended receiving antenna unit or system 10. The passive antennas 20, 21, and 22 are not electrically connected to the intended receiving antenna unit or system 10, other than via an electric ground, which is not shown in FIG. 6, so that the antennas 20, 21, and 22 are open circuited with respect to the intended receiving antenna unit or system 10.
Further, depending on the type of antenna, each passive open circuited antenna may be connected to a ground or surface plane. In addition, while this system uses three passive open circuited antennas, any number of passive sources may be used.
Like the direction finding and anti-jamming system shown in FIG. 5, the passive antennas 20 and 21 are positioned so that centers of the antennas 20 and 21 are spaced distances 90 and 91, respectively, from a center of the intended receiving unit or system 10 so as to form a triangle with the receiving unit or system 10. Preferably, the arrangement of the passive open circuited antennas 20 and 21 and the intended receiving antenna unit or system 10 forms an isosceles triangle, but any suitable configuration may be used. The antennas 20, 21, and 22 also form a triangle, preferably an isosceles triangle, and the centers of the passive antennas 20, 21, and 22 are spaced distances, 100, 101, and 102 relative to each other. As shown in FIG. 6, passive open circuited antennas 20 and 21 form a base of the triangle, and the base faces the intended receiving unit or system 10. Passive open circuited antenna 22 is positioned opposite the base formed by passive open circuited antennas 20 and 21 to form a vertex of the triangle, and the vertex faces an interfering signal source 5.
Since the passive antennas 20, 21, and 22 are placed between interference source 5 of the interfering signal β and the intended receiving unit or system 10, the system provides optimal reduction or suppression of the interference energy 6, as well as the most accurate identification of the direction of the interference energy 6. Specifically, since the direction of an interfering signal 6 forms a continuous straight line from the intended receiving unit or system 10 through the array of passive open circuited antennas 20, 21, and 22 to the interfering signal source 5, the intended receiving unit or system 10 performance is optimal. Further, even though the passive open circuit antennas 20, 21, and 22 are not placed directly between the intended receiving antenna unit or system 10 and interference sources 3 and 4 or interference signals 7 and 8, respectively, but rather are placed at angles relative to the intended receiving unit or system 10, the system also identifies the location of interference sources 3 and 4 and provides some suppression or reduction of interfering signal energies 7 and 8. An alternative embodiment of the present direction finding and anti-jamming system for use with severe intentional or unintentional RF jamming is shown in FIG 7. The system employs four passive open circuited antennas 20, 21, 22, and 23 placed directly between an interference signal source 5 of severe interfering signal 6 and the intended receiving antenna unit or system 10. The passive antennas 20, 21, 22, and 23 are not electrically connected to the intended receiving antenna unit or system 10, other than via an electric ground, which is not shown in FIG. 7, so that the antennas 20, 21, 22, and 23 are open circuited with respect to the intended receiving antenna unit or system 10. Further, depending on the type of antenna, each passive open circuited antenna may be connected to a ground or surface plane. While this system uses four passive open circuited antennas, any number of passive sources may be used.
Like the location finding and anti-jamming system shown in FIG. 5, the passive antennas 20 and 21 are positioned so that centers of the antennas 20 and 21 are spaced distances 90 and 91, respectively, from a center of the intended receiving unit or system 10 so as to form a triangle with the receiving unit or system 10. Preferably, the arrangement of the passive open circuited antennas 20 and 21 and the intended receiving antenna unit or system 10 forms an isosceles triangle, but any suitable configuration may be used. The antennas 20, 21, 22, and 23 are also placed so that the centers of the passive antennas 20, 21, 22, and 23 are spaced distances, 101, 102, 108, and 109, relative to each other. As shown in FIG. 7, passive open circuited antennas 20 and 21 are placed in a row generally parallel to a row containing passive antennas 22 and 23. Further, passive antennas 20 and 22 are positioned in a row substantially parallel to a row containing antennas 21 and 23. In addition, the antennas 20, 21, 22, and 23 are positioned to form two triangles, which are preferably equilateral triangles .
Since the passive antennas 20, 21, 22, and 23 are placed between interference source 5 of the interfering signal 6 and the intended receiving unit or system 10, the system provides optimal reduction or suppression of the interference energy 6. Further, even though the passive open circuit antennas 20, 21, 22, and 23 are not placed directly between the intended receiving antenna unit or system 10 and interference sources 3 and 4 or interference signals 7 and 8, respectively, but rather are placed at angles relative to the intended receiving unit or system 10, the system also identifies the location of interference sources 3 and 4 and provides some suppression or reduction of interfering signal energies 7 and 8.
Another embodiment of a direction finding and anti¬ jamming system is shown in FIG 8. This system employs multiple passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, and 27 surrounding the intended receiving antenna unit or system 10. The passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are not electrically connected to the intended receiving antenna unit or system 10, other than via an electric ground, which is not shown in FIG. 8, so that the antennas 20, 21, 22,
23, 24, 25, 26, and 27 are open circuited with respect to the intended receiving antenna unit or system 10. Further, depending on the type of antenna, each passive open circuited antenna may be connected to a ground or surface plane.
The antennas 20, 21, 22, 23, 24, 25, 26, and 27 are placed so that the centers of the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are spaced distances 90, 91, 92, 93, 94, 95, 96, and 97, respectively, from a center of the intended receiving unit or system 10. The passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are also positioned at distances 100, 101, 102, 103, 104, 105, 106, and 107 relative to each other, as shown in FIG. 8. Further, the passive open circuited antennas are positioned 20, 21, 22, 23, 24, 25, 26, and 27 are positioned around the intended receiving unit or system 10 so as to form triangles with the intended receiving unit or system 10. For example, passive open circuited antennas 20 and 21 form a triangle with the intended receiving unit or system 10 with sides with lengths corresponding to the distances 90, 91, and 100, as shown in Fig. 8.
A further embodiment of a direction finding and anti-jamming system is shown in FIG. 9. Similar to the system depicted in FIG. 8, this system also utilizes multiple passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, and 27 surrounding the intended receiving antenna unit or system 10. The antennas 20, 21, 22, 23,
24, 25, 26, and 27 are placed so that the centers of the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are spaced distances 90, 91, 92, 93, 94, 95, 96, and 97, respectively, from a center of the intended receiving unit or system 10. The passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are also positioned at distances 100, 101, 102, 103, 104, 105, 106, and 107 relative to each other, as shown in FIG. 9. Further, the passive open circuited antennas are positioned 20, 21, 22, 23, 24, 25, 26, and 27 are positioned around the intended receiving unit or system 10 so as to form triangles with the intended receiving unit or system 10.
This system also includes an additional parallel array of passive open circuited antennas N1^ N2, N3, N4, N5, N6, and Nn+L which represent a continuing line of passive open circuited antennas for protecting the intended receiving antenna unit 10 in cases of "severe" EMI. These passive antennas Nlf N2, N3, N4, N5, N6, and Nn+! are separated by distances M1 r M2j M3ι M4/ M5/ M6; M7, M8r M9r and Mm+lr creating parallel lines and triangles among passive open circuited antennas, as shown in FIG. 9.
Passive open circuited antennas can be mounted to adjustable slide brackets which are mounted to a common mounting base to allow the open circuited antennas to be adjusted relative to each other and to the intended receiving antenna unit or system 10. A location finding and anti-jamming system utilizing three passive open circuited antennas mounted to adjustable slide brackets is depicted in FIGS. 10 and 11. While this system uses three passive open circuited antennas, any number of antennas can be used. For example, multiple passive open circuited antennas can be arranged in groups of three around the intended receiving unit 10, and each group of three passive open circuited antennas can be mounted to an adjustable slide bracket.
As shown in FIGS. 10 and 11, the intended receiving antenna unit or system 10 is mounted to an adjustable slide pole 12 so that a height of the intended receiving antenna unit or system 10 relative to the passive open circuited antennas 20, 21, and 22 may be adjusted. The passive open circuited antennas 20, 21, and 22 are mounted to a slide bracket 150. Each of the passive open circuited antennas 20, 21, and 22 are received in a slot 161 in the slide bracket 150 so that the passive open circuited antennas 20, 21, and 22 may slide within the slots 161 and move distances 171. The slide bracket 150 may be connected to a servo step motor or other suitable moving means to move the passive open circuited antennas 20, 21, and 22 along the slots 161.
The slide bracket 150 is moveably mounted to a mounting base 190. Specifically, the slide bracket 150 is received in a slot 160 of the mounting base 190 so that the bracket 150 can slide within the slot 160 and move a distance 170. The mounting base 190 is also connected to a servo step motor 210 so that the base 190 can move 360° along a circular path 200 around the intended receiving unit 210. While a servo step motor 210 is preferred, any suitable driving means for moving the mounting base 190 around the intending receiving unit 10 may be used. To maximize EMI suppression or reduction and location finding capabilities , the height of the intended receiving antenna unit or system 10 may be adjusted based on an angle of incidence and direction of an interference signal. The position of the passive open circuited antennas 20, 21, and 22 relative to the intended receiving unit 10 can also be modified via the adjustable slide bracket mounting base 150 to optimize EMI and noise suppression or reduction and more accurately detect the location of an interfering signal source .
To further optimize the direction finding and antijamming system and method of the present invention, the following parameters may also be adjusted: a polarity match between the passive open circuited antennas and the interfering signal source, the height of the intended receiving antenna unit or system in relationship to the passive open circuited antennas, the number and physical arrangement of passive open circuited antennas surrounding the intended receiving antenna unit or system, the type of passive open circuited antennas used, the physical or electrical length of the passive open circuited antenna elements, the tilt angles of the passive open circuited antennas in the direction of the interfering signal, the distance between passive open circuited antennas and the intended receiving antenna unit or system, the distance between each passive open circuited antenna, the power density of the electromagnetic field, and angle of incidence and direction of the incoming undesired electromagnetic interference signal. As shown in Fig. 10, the passive open circuited antennas are preferably placed in groups of three around an intended receiving unit or system 10. An embodiment of a direction finding and anti-jamming system of the present invention utilizing a plurality of open circuited antennas placed in groups of three about an intended receiving unit or system 10 is shown in FIG 12. This system employs multiple passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, 27, 205, 225, 245, and 265 surrounding the intended receiving antenna unit or system 10. The passive antennas 20, 21, 22, 23, 24, 25, 26, 27, 205, 225, 245, and 265 are not electrically connected to the intended receiving antenna unit or system 10, other than via an electric ground, which is not shown in FIG. 12, so that the antennas 20, 21, 22, 23, 24, 25r 26, 27, 205, 225, 245, and 265 are open circuited with respect to the intended receiving antenna unit or system 10. Further, depending on the type of antenna, each passive open circuited antenna may be connected to a ground or surface plane.
The antennas 20, 21, 22, 23, 24r 25, 26, and 27 are placed so that the centers of the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are spaced distances 90, 91, 92, 93, 94, 95, 96, and 97, respectively, from a center of the intended receiving unit or system 10. The passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are also positioned at distances 100, 101, 102, 103, 104, 105, 106, and 107 relative to each other, as shown in FIG. 12. Further, the passive open circuited antennas are positioned 20, 21, 22, 23, 24, 25, 26, and 27 are positioned around the intended receiving unit or system 10 so as to form triangles with the intended receiving unit or system 10. For example, passive open circuited antennas 20 and 21 form a triangle with the intended receiving unit or system 10 having lengths 90, 91, and 100.
The passive open circuited antennas 205, 225, 245, and 265 also surround the intended receiving unit or system 10 and are placed at distances 200, 210, 220, 230, 240, 250, 260, and 270, respectively, from the passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, and 27. The passive open circuited antennas 205, 225, 245, and 265 are positioned to form triangles with the passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, and 27 between the intended receiving unit or system 10 and an interfering signal source. For example, passive open circuited antennas 20, 21, and 205 form a triangle having lengths 200, 210, and 100.
A further embodiment of a direction finding and anti-jamming system using groups of three passive antennas is shown in FIG= 13. This system also utilizes multiple passive open circuited antennas 20, 21, 22, 23, 24, 25, 26, 27, 225, 245, and 265 surrounding the intended receiving antenna unit or system 10. The antennas 20, 21, 22, 23, 24, 25, 26, and 27 are placed so that the centers of the passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are spaced distances 90, 91, 92, 93, 94, 95, 96, and 97, respectively, from a center of the intended receiving unit or system 10. The passive antennas 20, 21, 22, 23, 24, 25, 26, and 27 are also positioned at distances 100, 101, 102, 103, 104, 105, 106, and 107 relative to each other, as shown in FIG. 12. Further, the passive open circuited antennas are positioned 20, 21, 22, 23, 24, 25, 26, and 27 are positioned around the intended receiving unit or system 10 so as to form triangles with the intended receiving unit or system 10.
The passive open circuited antennas 225, 245, and 265 also surround the intended receiving unit or system 10 and are placed at distances 220, 230, 240, 250, 260, and 270, respectively, from the passive open circuited antennas 22, 23, 24, 25, 26, and 27. The passive open circuited antennas 225, 245, and 265 are positioned to form triangles with the passive open circuited antennas 22, 23, 24, 25, 26, and 27 between the intended receiving unit or system 10 and an interfering signal source. For example, passive open circuited antennas 22, 23, and 225 form a triangle having lengths 220, 230, and 102, as shown in Fig. 13.
This system also includes an additional parallel array of passive open circuited antennas N1, N2, N3, N4, N5, N6, and Nn+λ which represent a continuing line of passive open circuited antennas for protecting the intended receiving antenna unit 10 in cases of "severe" EMI. These passive antennas N1, N2, N3, N4, N5, N6, and Nn+! are separated by distances M1, M2, M3, M4, M5j M6, M7, M8, M9, and Mm+1, creating parallel lines and triangles among passive open circuited antennas, as shown in FIG. 13. The foregoing description of the present invention has been presented to illustrate the principles of the invention and not to limit the invention to the particular embodiments illustrated. It is intended that the scope of the invention be defined by all of the embodiments encompassed within the following claims and their equivalents.

Claims

I claim :
1. A passive antenna system for suppressing electromagnetic interference signals and determining a location of an interference signal source comprising: an electromagnetic energy source; a receiving antenna electrically connected to a receiver or transceiver for receiving electromagnetic energy from said electromagnetic energy source; and at least three passive open circuited antenna positioned in a triangle between said receiving antenna and an electromagnetic Interference signal from the interference signal source, wherein said at least three passive open circuited antenna are not electrically connected to said receiving antenna other than via an electrical ground.
2. The passive antenna system of claim 1, wherein said triangle includes a base facing said receiving antenna and a vertex facing the electromagnetic interference signal .
3. The passive antenna system of claim 2, wherein said at least three passive open circuited antennas are positioned between said receiving antenna and the electromagnetic interference signals so as to form a triangle with said receiving antenna.
4. The passive antenna system of claim 2, wherein each of said at least three passive open circuited antennas includes an adjustable base having up to six axes of freedom so that a position of each passive open circuited antenna is adjustable relative to said receiving antenna.
5. The passive antenna system of claim 2, further comprising: at least one bracket attached to said at least three passive open circuited antennas; and at least one base positioned between said receiving antenna and the electromagnetic interference signal, said base having at least one base slot for receiving said at least one bracket therein so that said at least one bracket is moveable along a length of said at least one base slot to adjust a position of said at least three passive open circuited antennas attached to said at least one bracket relative to said receiving antenna.
6. The passive antenna system of claim 5, further comprising a motor for moving said base relative to said receiving antenna.
7. The passive antenna system of claim 5, wherein said bracket includes a plurality of bracket slots, each of said plurality of bracket slots receiving each of said at least three passive open circuited antennas therein so that each of said at least three passive open circuited antennas is moveable along a length of each of said plurality of bracket slots to adjust a position of each of said at least three passive open circuited antennas .
8. The passive antenna system of claim 7, further comprising a motor for moving said at least three passive open circuited antennas within the plurality of bracket slots.
9. The passive antenna system of claim 2, wherein said receiving antenna is moveably mounted to a pole so that a distance between said receiving antenna and a ground level is adjustable.
10. A method for suppressing electromagnetic interference signals comprising: utilizing an electromagnetic energy source and a receiving antenna connected to a receiver or transceiver to transmit electromagnetic signals between the electromagnetic source and the receiver or transceiver; and placing at least three passive open circuited antennas to form a triangle between said receiving antenna and an electromagnetic interference signal, wherein said at least three passive open circuited antennas are not electrically connected to said receiving antenna other than via an electrical ground.
11. The method of claim 10, wherein said triangle includes a base facing said receiving antenna and a vertex facing the electromagnetic interference signal.
12. The method of claim 11, further comprising adjusting the position of said at least three passive open circuited antennas based on angles of incidence and direction of the electromagnetic interference signal . US2008/081615
13. The method of claim 11, further comprising adjusting the position of said at least three passive open circuited antennas based on a wavelength of the electromagnetic energy from the electromagnetic energy source .
14. The method of claim 11, further comprising adjusting the position of said at least three passive open circuited antennas based on wavelength of the electromagnetic interference signal .
15. The method of claim 11, further comprising adjusting the position of said at least three passive open circuited antennas based on a resonance of each passive open circuited antenna.
16. The method of claim 11, further comprising adjusting a length of each of said at least three passive open circuited antennas based on a wavelength of the electromagnetic energy from the electromagnetic energy source.
17. The method of claim 11, further comprising adjusting a length of each of said at least three passive open circuited antennas based on wavelength of the electromagnetic interference signal.
18. The method of claim 11, further comprising adjusting a polarization of each of said at least three passive open circuited antennas based on polarity of the electromagnetic interference signal . US2008/081615
19. A method for determining a location of an electromagnetic interference signal comprising: utilizing an electromagnetic energy source and a receiving antenna connected to a receiver or transceiver to transmit electromagnetic signals between the electromagnetic source and said receiver or transceiver; placing at least three passive open circuited antennas to form a triangle between said receiving antenna and an electromagnetic interference signal, wherein said at least three passive open circuited antennas are not electrically connected to said receiving antenna other than via an electrical ground; and extending a line connecting said receiving antenna and a center of said triangle in a direction of the electromagnetic interference signal .
20. The method of claim 19, wherein said triangle includes a base facing said receiving antenna and a vertex facing the electromagnetic interference signal.
PCT/US2008/081615 2008-03-27 2008-10-29 Receiver interference protection and direction finding antenna system WO2009120237A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP08873589A EP2274780A4 (en) 2008-03-27 2008-10-29 Receiver interference protection and direction finding antenna system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US6481208P 2008-03-27 2008-03-27
US61/064,812 2008-03-27

Publications (1)

Publication Number Publication Date
WO2009120237A1 true WO2009120237A1 (en) 2009-10-01

Family

ID=41114232

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2008/081615 WO2009120237A1 (en) 2008-03-27 2008-10-29 Receiver interference protection and direction finding antenna system

Country Status (2)

Country Link
EP (1) EP2274780A4 (en)
WO (1) WO2009120237A1 (en)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017111987A1 (en) * 2017-05-31 2018-12-06 Mbda Deutschland Gmbh Device for reducing interference in antennas
WO2022046529A1 (en) * 2020-08-28 2022-03-03 Isco International, Llc Method and system for mitigating interference by rotating antenna structures
US11476585B1 (en) 2022-03-31 2022-10-18 Isco International, Llc Polarization shifting devices and systems for interference mitigation
US11476574B1 (en) 2022-03-31 2022-10-18 Isco International, Llc Method and system for driving polarization shifting to mitigate interference
US11502404B1 (en) 2022-03-31 2022-11-15 Isco International, Llc Method and system for detecting interference and controlling polarization shifting to mitigate the interference
US11509072B1 (en) 2022-05-26 2022-11-22 Isco International, Llc Radio frequency (RF) polarization rotation devices and systems for interference mitigation
US11509071B1 (en) 2022-05-26 2022-11-22 Isco International, Llc Multi-band polarization rotation for interference mitigation
US11515652B1 (en) 2022-05-26 2022-11-29 Isco International, Llc Dual shifter devices and systems for polarization rotation to mitigate interference
US11949489B1 (en) 2022-10-17 2024-04-02 Isco International, Llc Method and system for improving multiple-input-multiple-output (MIMO) beam isolation via alternating polarization
US11956058B1 (en) 2022-10-17 2024-04-09 Isco International, Llc Method and system for mobile device signal to interference plus noise ratio (SINR) improvement via polarization adjusting/optimization
US11985692B2 (en) 2022-10-17 2024-05-14 Isco International, Llc Method and system for antenna integrated radio (AIR) downlink and uplink beam polarization adaptation
US11990976B2 (en) 2022-10-17 2024-05-21 Isco International, Llc Method and system for polarization adaptation to reduce propagation loss for a multiple-input-multiple-output (MIMO) antenna

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020008672A1 (en) * 1998-09-21 2002-01-24 Tantivy Communications, Inc. Adaptive antenna for use in wireless communication systems
US20070229390A1 (en) * 2000-02-01 2007-10-04 Science Applications International Corporation Passive anti-jamming antenna system

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2473421A (en) * 1945-05-30 1949-06-14 Fubini Eugene Search antenna array
US3383694A (en) * 1965-02-15 1968-05-14 Carll F. Strohmeyer Jr. Rotatable directional antenna attachment for use with a vertical antenna rod
US7057573B2 (en) * 2001-11-07 2006-06-06 Advanced Telecommuications Research Institute International Method for controlling array antenna equipped with a plurality of antenna elements, method for calculating signal to noise ratio of received signal, and method for adaptively controlling radio receiver
JP3867069B2 (en) * 2002-08-21 2007-01-10 株式会社国際電気通信基礎技術研究所 Radio wave arrival direction detection method and apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020008672A1 (en) * 1998-09-21 2002-01-24 Tantivy Communications, Inc. Adaptive antenna for use in wireless communication systems
US20070229390A1 (en) * 2000-02-01 2007-10-04 Science Applications International Corporation Passive anti-jamming antenna system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP2274780A4 *

Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017111987A1 (en) * 2017-05-31 2018-12-06 Mbda Deutschland Gmbh Device for reducing interference in antennas
WO2022046529A1 (en) * 2020-08-28 2022-03-03 Isco International, Llc Method and system for mitigating interference by rotating antenna structures
WO2022046532A1 (en) * 2020-08-28 2022-03-03 Isco International, Llc Method and system for polarization adjusting of orthogonally-polarized element pairs
US11705940B2 (en) 2020-08-28 2023-07-18 Isco International, Llc Method and system for polarization adjusting of orthogonally-polarized element pairs
US11881909B2 (en) 2020-08-28 2024-01-23 Isco International, Llc Method and system for mitigating interference by rotating antenna structures
US11956027B2 (en) 2020-08-28 2024-04-09 Isco International, Llc Method and system for mitigating interference by displacing antenna structures
US11949168B2 (en) 2022-03-31 2024-04-02 Isco International, Llc Method and system for driving polarization shifting to mitigate interference
US11502404B1 (en) 2022-03-31 2022-11-15 Isco International, Llc Method and system for detecting interference and controlling polarization shifting to mitigate the interference
US11817627B2 (en) 2022-03-31 2023-11-14 Isco International, Llc Polarization shifting devices and systems for interference mitigation
US11594821B1 (en) 2022-03-31 2023-02-28 Isco International, Llc Polarization shifting devices and systems for interference mitigation
US11476574B1 (en) 2022-03-31 2022-10-18 Isco International, Llc Method and system for driving polarization shifting to mitigate interference
US11626667B1 (en) 2022-03-31 2023-04-11 Isco International, Llc Polarization shifting devices and systems for interference mitigation
US11670847B1 (en) 2022-03-31 2023-06-06 Isco International, Llc Method and system for driving polarization shifting to mitigate interference
US11476585B1 (en) 2022-03-31 2022-10-18 Isco International, Llc Polarization shifting devices and systems for interference mitigation
US11705629B1 (en) 2022-03-31 2023-07-18 Isco International, Llc Method and system for detecting interference and controlling polarization shifting to mitigate the interference
US11876296B2 (en) 2022-03-31 2024-01-16 Isco International, Llc Polarization shifting devices and systems for interference mitigation
US11509072B1 (en) 2022-05-26 2022-11-22 Isco International, Llc Radio frequency (RF) polarization rotation devices and systems for interference mitigation
US11757206B1 (en) 2022-05-26 2023-09-12 Isco International, Llc Multi-band polarization rotation for interference mitigation
US11837794B1 (en) 2022-05-26 2023-12-05 Isco International, Llc Dual shifter devices and systems for polarization rotation to mitigate interference
US11705645B1 (en) 2022-05-26 2023-07-18 Isco International, Llc Radio frequency (RF) polarization rotation devices and systems for interference mitigation
US11611156B1 (en) 2022-05-26 2023-03-21 Isco International, Llc Dual shifter devices and systems for polarization rotation to mitigate interference
US11515652B1 (en) 2022-05-26 2022-11-29 Isco International, Llc Dual shifter devices and systems for polarization rotation to mitigate interference
US11509071B1 (en) 2022-05-26 2022-11-22 Isco International, Llc Multi-band polarization rotation for interference mitigation
US11949489B1 (en) 2022-10-17 2024-04-02 Isco International, Llc Method and system for improving multiple-input-multiple-output (MIMO) beam isolation via alternating polarization
US11956058B1 (en) 2022-10-17 2024-04-09 Isco International, Llc Method and system for mobile device signal to interference plus noise ratio (SINR) improvement via polarization adjusting/optimization
US11985692B2 (en) 2022-10-17 2024-05-14 Isco International, Llc Method and system for antenna integrated radio (AIR) downlink and uplink beam polarization adaptation
US11990976B2 (en) 2022-10-17 2024-05-21 Isco International, Llc Method and system for polarization adaptation to reduce propagation loss for a multiple-input-multiple-output (MIMO) antenna

Also Published As

Publication number Publication date
EP2274780A1 (en) 2011-01-19
EP2274780A4 (en) 2012-10-24

Similar Documents

Publication Publication Date Title
US7733288B2 (en) Passive anti-jamming antenna system and method
EP2274780A1 (en) Receiver interference protection and direction finding antenna system
US6930639B2 (en) Dual-element microstrip patch antenna for mitigating radio frequency interference
EP2522051B1 (en) Antenna beam control elements, systems, architectures, and methods for radar, communications, and other applications
US5629713A (en) Horizontally polarized antenna array having extended E-plane beam width and method for accomplishing beam width extension
CA3038622C (en) Anti-jamming and reduced interference global positioning system receiver methods and devices
US20090140921A1 (en) Radio Antenna Assembly and Apparatus for Controlling Transmission and Reception of RF Signals
US20120256804A1 (en) Reconfigurable mobile phone bulit-in antenna and implementation method thereof
US8493278B2 (en) Antennas and methods to provide adaptable omnidirectional ground nulls
US20130035052A1 (en) Circular Antenna Array for Satellite Communication Interference Rejection
CN110661098A (en) Auxiliary device for antenna system
US10236572B2 (en) Radio frequency chokes for integrated phased-array antennas
US6323806B1 (en) Antenna system and method for operating an antenna system
US11527837B2 (en) Dual polarised omnidirectional antenna apparatus
US20220085519A1 (en) High frequency system using a circular array
CN109687092B (en) Low-profile omnidirectional circularly polarized antenna
KR100875894B1 (en) Design method and device of dual polarized single beam antena using h shaped element array
KR101776518B1 (en) Arrangement of controlled reception pattern antenna
KR100822705B1 (en) Antenna for the direction finding of the phase comparison method
EP3503286B1 (en) Integrated antenna arrangement
CN107768799B (en) Antenna system
US12009915B2 (en) Compact receiver system with antijam and antispoof capability
US11843184B1 (en) Dual band, singular form factor, transmit and receive GNSS antenna with passively shaped antenna pattern
KR20140042072A (en) Apparatus and system for receiving wireless signal with anti-jamming
Merkley Alternative antenna architectures for land electronic warfare

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 08873589

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

WWE Wipo information: entry into national phase

Ref document number: 2008873589

Country of ref document: EP