US2337324A - Directional radio beacon - Google Patents

Directional radio beacon Download PDF

Info

Publication number
US2337324A
US2337324A US430904A US43090442A US2337324A US 2337324 A US2337324 A US 2337324A US 430904 A US430904 A US 430904A US 43090442 A US43090442 A US 43090442A US 2337324 A US2337324 A US 2337324A
Authority
US
United States
Prior art keywords
screen
dipole antenna
radiation
parts
antenna half
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US430904A
Other languages
English (en)
Inventor
Granqvist Carl-Erik
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AGA Baltic AB
Original Assignee
Individual
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 Individual filed Critical Individual
Application granted granted Critical
Publication of US2337324A publication Critical patent/US2337324A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves

Definitions

  • My invention relates to radio beacons.
  • the radio transmitter described in the said patent comprises a pair of dipole antenna half parts, i. e., two bars extending in the same longitudinal direction and preferably having a length of about A; wave length.
  • a grounded screen is interposed between the two half parts in a plane perpendicular thereto and an arrangement is provided for alternatingly connecting one or the other of the dipole antenna half parts with ground.
  • two field patterns are radiated which are symmetrical about the screen, and are so related that the field intensity in the longitudinal direction of the screen is the same for both patterns and therefore remains constant regardless of which half part is grounded.
  • the present invention relates to radio beacons "of the above described type in which a further increase in directional sharpness is obtained with a screen of smaller size.
  • Figs. 1 and 2 are polar diagrams illustrating the characteristics of the pattern
  • Figs. 3-5 are vector diagrams for explanation of the operations of the invention
  • Figs. 6 and '7 are perspective views and plan views respectively illustrating two different embodiments of the invention
  • Fig. 8 is a perspective view illustrating a transmitter embodying the present invention.
  • Fig. 8 illustrates diagrammatically a transmitter of the type shown in the above mentioned Patent No. 2,309,063 which comprises a pair of oppositely extending dipoles H and I2, a grounded screen l3 connected therebetween, a transmitter 40 connected by lines 4] and 42 to the respective dipoles H and l2, 2.
  • switch 43 actuated by a relay 44 to selectively connect the dipoles II and I2 to ground through the screen [3 and a code mechanism 45 which actuates the switch relay M in a timed sequence corresponding to the code signals to be transmitted.
  • Fig. 1 two antenna half parts II and I2 of a pair of dipole antennas are shown with a screen I3 disposed therebetween as above described.
  • the dipole antenna pair would, if the screen were not present, have the radiation characteristic indicated by the dotted line l4. If the screen had infinite extension, on the other hand, a radiation characteristic indicated by lines I5 and It, would be obtained. As, however, the screen has a limited extension, a radiation characteristic which is intermediate in form between the two characteristics l4 and l5-l6 is obtained.
  • the present invention is based upon an investigation of the form of the characteristic with screens of different intermediate finite areas. Beginning with an infinite extension of the screen, corresponding to the characteristic l5 for the antenna half part I! and the characteristic it re the antenna half part l2, if the dimensions of the screen 13 are rogressively decreased, a correspondingly increasing capacitive coupling will occur between the two antenna half parts, causing one of the half parts, even if it is grounded, to radiate actively with a field intensity which is among other things dependent upon the degree of capacitive coupling between the two antenna half parts.
  • the field diagrams will therefore change their character, the diagram 15 changing into the form l1, and the diagram l6 changing into the form l8.
  • the loop-shaped diagram thus formed will be positioned with a major part on that side of the screen where the fed antenna part is situated and with a minor part on that side of the screen where the grounded antenna half part is situated.
  • a continued decrease of the dimensions of the screen l3 will cause an increased coupling between the fed and the grounded antenna half parts, and consequently that part of the loop characteristic which is positioned on the side of the fed antenna half part will continuously decrease, whereas the part of the loop characteristic which is positioned on the side of the grounded antenna half part is increased to a corresponding degree.
  • the characteristic will be substantially symmetrical about the plane of the screen and hence will intersect with the plane of the screen at a right angle. This dimension of the screen is herein called the critical magnitude of the screen.
  • the dipole antenna half parts which are assumed to have a length of exactly a quarter of a wave length, may for simplicity be considered as concentrated radiation points situated at the mid-point of the dipole antenna half part, that is, at a distance of one eighth of a wave length from the screen. It is assumed in the following that the dipole antenna half part i2 is grounded, whereas the dipole antenna half part Ii is connected to the source of voltage. Due to the incompleteness of the screen l3 it is not possible to prevent capacitive transfer to and radiation from the dipole antenna half part l2.
  • the radiation current from this dipole antenna half part will vary according to the capacity between the half parts and the inductance of the antenna half parts and their length as compared with the wavelength. Hence in certain instances the currents in both of the dipole antenna half parts may be equal. For simplicity it is assumed that this is the case. It should be noted, however, that in this the ideal shape of characteristic will not ordinarily be obtained.
  • the radiation from the dipole antenna half part l2 due to the capacitive voltage transfer is about 90 displaced in phase in relation to the radiation from the dipole antenna half part H.
  • a further displacement in phase caused by the propagation time of the radiation which on one side of the screen is added to the capacitive displacement in phase caused by the coupling between the dipole antenna half parts, but on the other side of the screen is opposed to the last named displacement in phase.
  • the radiation can be considered to emanate from the electrostatical center of gravity of the dipole antenna half parts.
  • the two centers are situated in a distance from each other of about one quarter of a wave length if the dipole antenna half parts are of the usual length of one quarter length each.
  • the propagation time for one of the radiation waves, until it coincides with the other propagation wave may therefore be represented by a simple graphical construction.
  • the radiation in the direction ad thus will cooperate with a radiation from the dipole antenna half part 52 in the direction ce, which is 90 displaced in phase due to the capacitive coupling and is isplaced in phase in the same direction due to the time of propagation of the wave, that is, it will have a total phase displacement of 155.
  • the shape of the characteristic 22 is based on the assumption that the radiation from both of the antenna half parts are equal. However, this is usually not the case, and, by suitable dimensioning of the difierent parts of the antenna system an intersecting angle 23 between the characteristic 22 and the plane of the screen 23 may be obtained which, at the optimal magnitude of the screen, is substantially less than that shown in Fig. 2. The same angle may also be obtained with a magnitude of the screen 83 which is greater than the critical magnitude, although in this case the characteristics will have changed their places. However, in the last case the screen will be so large, that for purely practical reasons it could not be used. This is especially the case when the radio beacon is to be made portable.
  • the dipole antenna half parts are usually connected with the two leads to a radio frequency generator, the screen being connected with a contact spring which is oscillated between two counter-contacts, one of which is connected to one of the dipole antenna half parts and the other one to the other dipole antenna half part in time with e complement code such as the Morse letters ET. Consequently the radiation from the antenna system will assume the character Of a diagram alternating from the diagram l! to the diagram l8, Fig. l, and a listener in any direction except in the plane of the screen will always observe a change in the observed sound intensity of the two signals. The precision with which the correct direction can be determined will therefore be directly proportional to tangent of the angle 23 at which the diagram intersects the plane of the screen.
  • this disadvantage is obviated by providing the antenna system with one or more effective reflectors on that side,
  • the disturbing radiation reflections are cated, said reflectors being designed in such a manner that they do not perceptibly impair the radiation pattern, but preferably even sharpen the angle 23 of the radiation diagram.
  • the screen have an extension which is suflicient to screen the reflectors, which have the form of bars connected to the screen, in substantially the same manner as the two dipole antenna half parts are screened.
  • Fig. 6 is a perspective view of an antenna system according to the invention, having one reflector.
  • the two dipole antenna half parts are indicated at 24 and 25. It is assumed that they are the usual one quarter of a wave length long.
  • the screen is composed of bars 25-33, welded together or joined together in some other way, and symmetrically arranged about the bar 26 which crosses the plane of the dipole antenna half part at a distance of about one eighth of a wave length from said half parts.
  • two bars 34 and 35 are arranged. These are also about one quarter of a wave length long and are, as will be evident from the above, situated at a distance from the dipole antenna of about one quarter of a wave length.
  • the bars 3d and 35 are further metallically connected to the screen. In this case the best possible reflection is obtained. Consequently the diagram will be exactly equal to that according to Fig. 1, except in two respects, namely the allover field intensity will be proportionally stronger, and the loop which is removed by the reflectors will be missing.
  • the spacing and the length of the reflectors may be varied to control the shape of the characteristic.
  • the rules for the deviation in form and position, which should be made, are, however, individual for each case and may suitably be determined empirically. As a rule the reflector bars 34 and 35 should be somewhat longer than the dipole antenna bars 24 and 25.
  • the directors may be arranged as shown in Fig. 7.
  • the screen is shown in plan view in the plane of the paper, the dipole antennas, the reflectors and the directors thus having a direction perpendicular to the plane of the paper.
  • the dipoles are arranged at the point 36 and the reflectors at the point 31 as shown in Fig. 6.
  • the distance between the points 36 and 31, as in the arrangement according to Fig. 6, is substantially a quarter of a wave length.
  • a further pair of bars is arranged at the point 38.
  • a directional radio beacon comprising a dipole antenna having a pair of longitudinal halfparts extending in opposite directions, a screen interposed between said half-parts in a plane normal thereto, a transmitter feeding said antenna and timed mechanism to alternately ground said half-parts, said screen having an extension less than the critical magnitude at which the radiation characteristic of each half-part, when the other half-part is grounded, intersects the plane of the screen at substantially a right angle.
  • a directional radio beacon as set forth in claim 1 in which the screen is of the optimum magnitude at which said characteristic intersects the plane of the screen at the minimum angle.
  • a directional radio beacon according to claim 1 in which the screen is made in the form of a net-work of metallic bars.
  • a directional radio beacon according to claim 1 in which the screen is metallically connected with two reflector bars which extend parallel to the dipole antenna half-parts.
  • a directional radio beacon according to claim 1 in which the screen is metallically connected with two reflector bars which extend parallel to the dipole antenna half-parts, and is arranged symmetrically about a line which forms a center line joining the points of intersection of the screen with the antennas and the reflector bars.
  • a directional radio beacon according to claim 1 in which the screen is metallically connected with two reflector bars which extend parallel to the dipole antenna half-parts, the distance between the dipole antenna half-parts and the reflector bars being substantially one-quarter of the wave-length for which the radio beacon is designed.
  • a directional radio beacon according to claim 1 in which the screen is metallically connected with two reflector bars which extend, parallel to the dipole antenna half-parts, the reflector bars being somewhat longer than the dipole antenna half-parts.
  • a directional radio beacon according to claim 1 in which the screen is metallically connected to at least one pair of director bars which extend parallel to the dipole antenna half-parts.
  • a directional radio beacon according to claim 1 in which the screen is metallically connected to at least one pair of director bars which extend parallel to the dipole antenna half-parts, the distance between the dipole antenna halfparts and the director bars being substantially a half of the wave-length for which the directed radio beacon is designed.
  • a directional radio beacon according to claim 1 in which the screen is metallically connected to at least one pair of director bars which extend parallel to the dipole antenna half-parts, the director bars being somewhat shorter than the dipole antenna half-parts.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Aerials With Secondary Devices (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
US430904A 1941-01-13 1942-02-14 Directional radio beacon Expired - Lifetime US2337324A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE551773X 1941-01-13

Publications (1)

Publication Number Publication Date
US2337324A true US2337324A (en) 1943-12-21

Family

ID=20311801

Family Applications (1)

Application Number Title Priority Date Filing Date
US430904A Expired - Lifetime US2337324A (en) 1941-01-13 1942-02-14 Directional radio beacon

Country Status (3)

Country Link
US (1) US2337324A (fr)
FR (1) FR879657A (fr)
GB (1) GB551773A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2474238A (en) * 1945-06-27 1949-06-28 Myron Y Eck Single null loop antenna
US2489287A (en) * 1946-03-26 1949-11-29 Guarino Pasquale Anthony Antenna
US2567746A (en) * 1946-03-05 1951-09-11 Lester C Van Atta Antenna
US2684445A (en) * 1946-03-29 1954-07-20 Us Navy Lobe switching antenna

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2474238A (en) * 1945-06-27 1949-06-28 Myron Y Eck Single null loop antenna
US2567746A (en) * 1946-03-05 1951-09-11 Lester C Van Atta Antenna
US2489287A (en) * 1946-03-26 1949-11-29 Guarino Pasquale Anthony Antenna
US2684445A (en) * 1946-03-29 1954-07-20 Us Navy Lobe switching antenna

Also Published As

Publication number Publication date
GB551773A (en) 1943-03-09
FR879657A (fr) 1943-03-02

Similar Documents

Publication Publication Date Title
US2415094A (en) Radio measurement of distances and velocities
US3231892A (en) Antenna feed system simultaneously operable at two frequencies utilizing polarization independent frequency selective intermediate reflector
US2507528A (en) Antenna
US3725938A (en) Direction finder system
US1745342A (en) Directive-projecting system of electric waves
US2650985A (en) Radio horn
US3474452A (en) Omnidirectional circularly polarized antenna
US2316151A (en) Electromagnetic horn
US2380333A (en) High frequency antenna
US2611869A (en) Aerial system
US20250273861A1 (en) Multi-band antennas having enhanced directors therein that inhibit radiation interference across multiple frequency bands
US2337324A (en) Directional radio beacon
US4063249A (en) Small broadband antenna having polarization sensitive reflector system
US2210491A (en) High frequency antenna
US2217321A (en) Beam antenna
US2153589A (en) Antenna
US2897496A (en) Corner reflector antenna
US2687475A (en) Low-frequency antenna
US2401601A (en) Antenna
US2647256A (en) Radar system
US2549783A (en) Antenna
US2192187A (en) High frequency transmitter
US2141247A (en) Arrangement for wireless signaling
US2151922A (en) Receiver for electromagnetic waves
US2489615A (en) Radio aid to air navigation