US3411111A - Mast for loop direction finding system - Google Patents

Mast for loop direction finding system Download PDF

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Publication number
US3411111A
US3411111A US506920A US50692065A US3411111A US 3411111 A US3411111 A US 3411111A US 506920 A US506920 A US 506920A US 50692065 A US50692065 A US 50692065A US 3411111 A US3411111 A US 3411111A
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United States
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mast
ferrite
direction finding
cable
cylinder
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US506920A
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Jr Elmer A Meyers
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US Department of Army
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Army Usa
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    • 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
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/04—Details
    • G01S3/06—Means for increasing effective directivity, e.g. by combining signals having differently oriented directivity characteristics or by sharpening the envelope waveform of the signal derived from a rotating or oscillating beam antenna
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/24—Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction
    • H01Q21/26—Turnstile or like antennas comprising arrangements of three or more elongated elements disposed radially and symmetrically in a horizontal plane about a common centre

Definitions

  • This invention relates to a mast for a loop direction finding antenna and more particularly to a mast having a ferrite choke therein to prevent undesirable oscillations from occurring in the mast.
  • sence information is obtained by adding the signals from a loop antenna and a monopole antenna after one of them has been shifted ninety degrees in phase.
  • Phase shifts in the monopole signal due to changes in the height of the antenna above ground and various ground conditions can completely destroy the sense information or cause it to be erroneous.
  • the height above ground problem is due primarily to different modes of oscillation in the mast or mast structure wavelength resonances). Since the antenna head supported by the mast contains a preamplifier, power and control wires, a coaxial cable must necessarily be strung through the mast. Therefore, resonances will occur with both dielectric and metal masts.
  • the solution to the above mentioned problem is obtained by lowering the Q of the mast structure. This is accomplished by fabricating the mast wiring into a cable which is covered with a shield braid on which a ferrite coaxial choke in connected.
  • An object of the present invention is to provide a mast for a direction finding antenna including a ferrite choke for preventing undesirable resonances in the mast structure and thereby preserving the sense information obtained by said direction finding antenna.
  • FIGURE 1 is a cut-away view of the mast showing the wiring and choke therein, and
  • FIGURE 2 shows a particular choke which may be used in the mast.
  • FIGURE 1 there is shown a mast 11 which may be made from fiber glass tubing.
  • the mast wiring is fabricated into a cable 12 which is covered with shield braid 13 which connects to a connector 14 at the top of the mast to provide complete shielding.
  • a similar connector (not shown) is attached to the braid 13 at the bottom of the mast.
  • a coaxial ferrite choke 15 is supported within the mast tubing by four plastic foam supports 16.
  • the ferrite choke is insulated from the shield braid along the entire length of the choke except at its upper end where the braid and the choke are conductively connected together by solder 17.
  • the insulation is provided by wrapping plastic insulative tape 18 around the shield braid throughout the length of the choke.
  • FIGURE 2 shows the construction of a preferred embodiment of the ferrite choke 15.
  • the ferrite cylinder shown in FIGURE 2 comprises a stack of doughnutshaped ferrite rings 21 around which is wrapped a sheet of brass 22 (see FIG. 1). Brass discs 23 and 24 are soldered to the top and bottom of the ferrite cylinder.
  • the overall dimensions of the choke are related to the type of material used and the frequency of operation; the optimum size can be determined by a cut and try procedure.
  • a lossy ferrite material is used, tending to lower the Q of the mast structure and provide broad band operation.
  • a mast for a direction finding antenna comprising: an elongated tubular mast; a shielded cable extending throughout the entire length of said tubular mast; a hollow ferrite cylinder supported within said tubular mast, said cable passing through the hollow portion of said ferrite cylinder; means for insulating said cable from said ferrite cylinder throughout the length of said ferrite cylinder except at the extreme top end thereof; means for conductively connecting the extreme top end of said ferrite cylinder to said cable; a thin conductive cylinder surrounding the outer portion of said ferrite cylinder and two conductive discs, one conductively joined to each end of said cylinder and to said conductive cylinder.
  • a mast for a direction finding antenna comprising: an elongated tubular mast; a ferrite cylinder supported within said mast by a plurality of elongated plastic foam sections, said cylinder having an axial hole therein and a metallic covering on the outer surface and the two end surfaces thereof; a shielded cable extending through said mast and through the hole in said cylinder, the portion of said cable within said cylinder having an insulative cov-' ering; and means for conductively connecting the end of said ferrite cylinder which is located in the uppermost part of said mast to said cable.
  • a mast as set forth in claim 5 which further includes an electrical connector attached to each end of said cable.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Details Of Aerials (AREA)

Description

Nov. 12, 1968 E. A. MEYERS. JR
MAST FOR LOOP DIRECTION FINDING Filed Nov. 5, 1965 ll IIIllllllllllllalllllllll'll .vv. PWwuF: 5% @Br m INVENT ELMER A\M Y RS I d- 'W, M Z.
ATTORNEYS United States Patent 3,411,111 MAST FOR LOOP DIRECTION FINDING SYSTEM Elmer A. Meyers, Jr., Cupertino, Calif., assignor by mesne assignments, to the United States of America as represented by the Secretary of the Army Filed Nov. 5, 1965, Ser. No. 506,920 6 Claims. (Cl. 33312) This invention relates to a mast for a loop direction finding antenna and more particularly to a mast having a ferrite choke therein to prevent undesirable oscillations from occurring in the mast.
In the operation of a direction finding antenna, sence information is obtained by adding the signals from a loop antenna and a monopole antenna after one of them has been shifted ninety degrees in phase. Phase shifts in the monopole signal due to changes in the height of the antenna above ground and various ground conditions can completely destroy the sense information or cause it to be erroneous. The height above ground problem is due primarily to different modes of oscillation in the mast or mast structure wavelength resonances). Since the antenna head supported by the mast contains a preamplifier, power and control wires, a coaxial cable must necessarily be strung through the mast. Therefore, resonances will occur with both dielectric and metal masts.
In the system in which this new mast is used some means for preserving the sense information is necessary. One method for preserving-this information is to mount a ground plane below the monopole antenna. The ground plane establishes a ground reference for the monopole and is a solution to the problem. However, it is not a very practical solution since the ground plane assembly is unwieldly to rotate and does not lend itself to portable operation. The structure described herein is an excellent solution to the problem of preserving sense information as it allows the desired performance of the system to be obtained without the use of a cumbersome ground plane.
The solution to the above mentioned problem is obtained by lowering the Q of the mast structure. This is accomplished by fabricating the mast wiring into a cable which is covered with a shield braid on which a ferrite coaxial choke in connected.
An object of the present invention is to provide a mast for a direction finding antenna including a ferrite choke for preventing undesirable resonances in the mast structure and thereby preserving the sense information obtained by said direction finding antenna.
The nature of the present invention along with various advantages, objects and features thereof will become more apparent upon consideration of the accompanying drawings and the following detailed description of those drawings.
In the drawings:
FIGURE 1 is a cut-away view of the mast showing the wiring and choke therein, and
FIGURE 2 shows a particular choke which may be used in the mast.
Referring to FIGURE 1 there is shown a mast 11 which may be made from fiber glass tubing. The mast wiring is fabricated into a cable 12 which is covered with shield braid 13 which connects to a connector 14 at the top of the mast to provide complete shielding. A similar connector (not shown) is attached to the braid 13 at the bottom of the mast.
A coaxial ferrite choke 15 is supported within the mast tubing by four plastic foam supports 16. The ferrite choke is insulated from the shield braid along the entire length of the choke except at its upper end where the braid and the choke are conductively connected together by solder 17. The insulation is provided by wrapping plastic insulative tape 18 around the shield braid throughout the length of the choke.
FIGURE 2 shows the construction of a preferred embodiment of the ferrite choke 15. The ferrite cylinder shown in FIGURE 2 comprises a stack of doughnutshaped ferrite rings 21 around which is wrapped a sheet of brass 22 (see FIG. 1). Brass discs 23 and 24 are soldered to the top and bottom of the ferrite cylinder.
The overall dimensions of the choke are related to the type of material used and the frequency of operation; the optimum size can be determined by a cut and try procedure. A lossy ferrite material is used, tending to lower the Q of the mast structure and provide broad band operation.
What is claimed is:
1. A mast for a direction finding antenna comprising: an elongated tubular mast; a shielded cable extending throughout the entire length of said tubular mast; a hollow ferrite cylinder supported within said tubular mast, said cable passing through the hollow portion of said ferrite cylinder; means for insulating said cable from said ferrite cylinder throughout the length of said ferrite cylinder except at the extreme top end thereof; means for conductively connecting the extreme top end of said ferrite cylinder to said cable; a thin conductive cylinder surrounding the outer portion of said ferrite cylinder and two conductive discs, one conductively joined to each end of said cylinder and to said conductive cylinder.
2. A mast as set forth in claim 1 in which said ferrite cylinder comprises a plurality of doughnut-shaped ferrite rings.
3. A mast as set forth in claim 1 wherein said insulating means consists of insulative tape wrapped around said cable.
4. A mast for a direction finding antenna comprising: an elongated tubular mast; a ferrite cylinder supported within said mast by a plurality of elongated plastic foam sections, said cylinder having an axial hole therein and a metallic covering on the outer surface and the two end surfaces thereof; a shielded cable extending through said mast and through the hole in said cylinder, the portion of said cable within said cylinder having an insulative cov-' ering; and means for conductively connecting the end of said ferrite cylinder which is located in the uppermost part of said mast to said cable.
5. A mast as set forth in claim 4 in which said tubular mast is made of fiber glass.
6. A mast as set forth in claim 5 which further includes an electrical connector attached to each end of said cable.
References Cited UNITED STATES PATENTS 2,111,651 3/1938 Wentz 33312 2,322,971 6/1943 Roosenstein 33312 2,419,855 4/ 1947 Roosenstein 33312 2,524,857 10/ 1950 Secker 33381 2,669,695 2/1954 Bird 33312 3,035,237 5/1962 Schlicke 33379 3,380,004 4/ 1968 Hansen 33379 FOREIGN PATENTS 603,1 19 6/1948 Great Britain. 887,578 1/ 1962 Great Britain.
ELI LIEBERMAN, Primary Examiner. W. H. PUNTER, Assistant Examiner.

Claims (1)

1. A MAST FOR A DIRECTION FINDING ANTENNA COMPRISING: AN ELONGATED TUBULAR MAST; A SHIELDED CABLE EXTENDING THROUGHOUT THE ENTIRE LENGTH OF SAID TUBULAR MAST; A HOLLOW FERRITE CYLINDER SUPPORTED WITHIN SAID TUBULAR MAST, SAID CABLE PASSING THROUGH THE HOLLOW PORTION OF SAID FERRITE CYLINDER; MEANS FOR INSULATING SAID CABLE FROM SAID FERRITE CYLINDER THROUGHOUT THE LENGTH OF SAID FERRITE CYLINDER EXCEPT AT THE EXTREME TOP END THEREOF; MEANS FOR CONDUC-
US506920A 1965-11-05 1965-11-05 Mast for loop direction finding system Expired - Lifetime US3411111A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3569972A (en) * 1968-07-10 1971-03-09 William J Mcevoy Electronically tunable antenna
US3680146A (en) * 1970-03-02 1972-07-25 Jerrold Electronics Corp Antenna system with ferrite radiation suppressors mounted on feed line
US3717877A (en) * 1970-02-27 1973-02-20 Sanders Associates Inc Cavity backed spiral antenna
US3789299A (en) * 1969-08-08 1974-01-29 Narda Microwave Corp Probe for radiation detector
US4536714A (en) * 1982-04-16 1985-08-20 Schlumberger Technology Corporation Shields for antennas of borehole logging devices
USRE32913E (en) * 1982-04-16 1989-04-25 Schlumberger Technology Corp. Shields for antennas of borehole logging devices
US4958134A (en) * 1987-09-04 1990-09-18 Kabushiki Kaisha Toshiba Noise suppression device comprising a toroid winding
US6351245B1 (en) * 1999-12-10 2002-02-26 Em-Tech Llc Use of phase coded permeability lensing to obtain directional information in electro-magnetic radiation
US20150276459A1 (en) * 2014-03-28 2015-10-01 Honeywell International Inc. Foam filled dielectric rod antenna
US10733166B1 (en) 2017-05-03 2020-08-04 Northrop Grumman Systems Corporation Nested icosahedral grid

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2111651A (en) * 1936-08-13 1938-03-22 Bell Telephone Labor Inc High-frequency transmission system
US2322971A (en) * 1939-04-11 1943-06-29 Roosenstein Hans Otto Shielded antenna feeder lead or line
US2419855A (en) * 1939-06-22 1947-04-29 Roosenstein Hans Otto Arrangement adapted to suppress radio frequency currents on conductors
GB603119A (en) * 1944-04-28 1948-06-09 Philco Radio & Television Corp Improvements in or relating to electrically resonant cavities
US2524857A (en) * 1945-07-10 1950-10-10 Int Standard Electric Corp Electric attenuating device
US2669695A (en) * 1952-09-23 1954-02-16 Breeze Corp High attenuation shielded lead structure
GB887578A (en) * 1959-06-01 1962-01-17 Atlas Werke Ag Improvements in or relating to antenna arrangements
US3035237A (en) * 1958-03-10 1962-05-15 Allen Bradley Co Feed-through capacitor
US3380004A (en) * 1959-01-20 1968-04-23 Mcmillan Corp Of North Carolin Aperiodic low-pass filter

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2111651A (en) * 1936-08-13 1938-03-22 Bell Telephone Labor Inc High-frequency transmission system
US2322971A (en) * 1939-04-11 1943-06-29 Roosenstein Hans Otto Shielded antenna feeder lead or line
US2419855A (en) * 1939-06-22 1947-04-29 Roosenstein Hans Otto Arrangement adapted to suppress radio frequency currents on conductors
GB603119A (en) * 1944-04-28 1948-06-09 Philco Radio & Television Corp Improvements in or relating to electrically resonant cavities
US2524857A (en) * 1945-07-10 1950-10-10 Int Standard Electric Corp Electric attenuating device
US2669695A (en) * 1952-09-23 1954-02-16 Breeze Corp High attenuation shielded lead structure
US3035237A (en) * 1958-03-10 1962-05-15 Allen Bradley Co Feed-through capacitor
US3380004A (en) * 1959-01-20 1968-04-23 Mcmillan Corp Of North Carolin Aperiodic low-pass filter
GB887578A (en) * 1959-06-01 1962-01-17 Atlas Werke Ag Improvements in or relating to antenna arrangements

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3569972A (en) * 1968-07-10 1971-03-09 William J Mcevoy Electronically tunable antenna
US3789299A (en) * 1969-08-08 1974-01-29 Narda Microwave Corp Probe for radiation detector
US3717877A (en) * 1970-02-27 1973-02-20 Sanders Associates Inc Cavity backed spiral antenna
US3680146A (en) * 1970-03-02 1972-07-25 Jerrold Electronics Corp Antenna system with ferrite radiation suppressors mounted on feed line
US4536714A (en) * 1982-04-16 1985-08-20 Schlumberger Technology Corporation Shields for antennas of borehole logging devices
USRE32913E (en) * 1982-04-16 1989-04-25 Schlumberger Technology Corp. Shields for antennas of borehole logging devices
US4958134A (en) * 1987-09-04 1990-09-18 Kabushiki Kaisha Toshiba Noise suppression device comprising a toroid winding
US6351245B1 (en) * 1999-12-10 2002-02-26 Em-Tech Llc Use of phase coded permeability lensing to obtain directional information in electro-magnetic radiation
US20150276459A1 (en) * 2014-03-28 2015-10-01 Honeywell International Inc. Foam filled dielectric rod antenna
US9273989B2 (en) * 2014-03-28 2016-03-01 Honeywell International Inc. Foam filled dielectric rod antenna
US10733166B1 (en) 2017-05-03 2020-08-04 Northrop Grumman Systems Corporation Nested icosahedral grid

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