US2480172A - Radio antenna - Google Patents

Radio antenna Download PDF

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Publication number
US2480172A
US2480172A US573099A US57309945A US2480172A US 2480172 A US2480172 A US 2480172A US 573099 A US573099 A US 573099A US 57309945 A US57309945 A US 57309945A US 2480172 A US2480172 A US 2480172A
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US
United States
Prior art keywords
antenna
transmission line
mean
stub
impedance
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
US573099A
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English (en)
Inventor
Willoughby Eric Osborne
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International Standard Electric Corp
Original Assignee
International Standard Electric Corp
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Filing date
Publication date
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Application granted granted Critical
Publication of US2480172A publication Critical patent/US2480172A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
    • H01Q9/28—Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines

Definitions

  • the present invention relates to radio antenna systems and it has for its chief object to provide an antenna system for use at ultra high frequencies, for example 100-150 megacycles which has a substantially flat amplitude-frequency characte'ri'stic over a wide frequency band of the order or 20% of the mean fre uency on either side of said mean frequency.
  • an antenna system having a substantially constant resistance over a broad operating band of ultra high fre'qu'en'c'ies includes an antenna comprising a hollow conducting cylinder erected vertically above the ground but insulated from it and havinga physical length between one quarter and one half the mean operating wave length, and half wave resonant at the mean operating frequency, a central conductor which passes through said hollow cylinder to form therewith a stub and means for tuning the said stub to resonance at the mean operating frequency, a transmission line preferably screened for coupling said antenna to a translation device and a quarter wave line im: pedance transformer at substantially said mean frequency coupling said antenna and said transline.
  • a dipole radio antenna system having a substantially constant resistance over a broad operatingband of ultra high frequencies includes a dipoleantenna comprising two hollow conducting cylinders each having aphysical length between one quarter and one half the mean operating wave length, and half wave resonant at the mean operating frequency, central conductors which pass through the respective hollow cylinders forming stubs therewith and means for tuning said stubs to resonance at the mean operating frequency, a transmission line preferably screened for coupling the antenna to a translation device, and a quarter wave line impedance transformer at substantially said mean frequency coupling said antenna and" said transmission line.
  • the lower end of the vertical antenna is prefer ably conical and tapers towards the ground and the inner ends of the dipole cylindrical members are preferably conical tapering towards each other, and the physical length of the vertical antenna, or each of the dipole members tuned to half waveresonance is between one quarter and one half the mean operating wave length.
  • An antenna embodying the invention is effectively fed; from the conical end; since the waves pass down the inside of the cylinders from the cylindrical end and along" the outside of the cylinder from the conical end during the radiating' action.
  • the reverse action takes lace.
  • An antenna of low characteristic impedance is employed thereby keeping the end radiation resistance' low and a transmission line of relatively high characteristic impedance (particularly if ascre'ene'd" line-is desired) is employed to reduce the impedance transformation ratio in order that a quarter wave line impedance transformer may we used for coupling the antenna and transmission line.
  • the antenna is series tuned throughout the frequency band by using series tuned elements of appropriate value in series with the antenna thus taking advantage of ⁇ the fact that the reactance of a half wave antenna varies in the opposite direction with frequency through resonance as does a series tuned circuit consisting of series connected inductance" and capacity.
  • the series tuning of the antenna throughout the frequency band canbe carried out sufficiently well that the antenna may be considered as a substantially ure resistancevarying with frequencyac'cofding' to a law represented by a smooth curve with-the maximum near the centre of the operating band substantially twice as high as that on the extremes of the operating band, and the problem of coupling tlie'an'tenna to a transmission line then resolves itself into matching the characteristic impedance of the transmission line with that of the said pure resistanc varying in the manner stated.
  • Z9 is the characteristic impedance of the reed line
  • a quarter wave impedance matching transformer whose impedance is /R,Zo where R istlie mean resistance of the antenna over the frequency band, gives an impedance mismatch between the antenna and line of the order 5:4, i.- e. o'fthe order of 0.2 db.
  • Such a coupling unit is compact and'by slight over-compensation of the antenna as seen at its reaetance of the half-wave base, the s'm'all' reactance-introduced by deviation of thematcfiing transformer from quarter wavelength-in the tuning band'lcan be largely compensated';
  • overcompensation is meant introducing a greater series reactance than is required for neutralisation of the antenna reactance 1n the operating frequency band.
  • Such a quarter wave line coupling impedance transformer is thus suitable for coupling the antenna and a screened transmission line. With a coupling unit of this type the losses at the extremes of the frequency band are smaller the lower the impedance transformation ratio.
  • Such a coupling unit has also mechanical advantages since it is extremely compact, rigid, and simple, and can be carried with the antenna at the end of a long length of transmission line, whereas a more theoretically perfect coupling unit involves a plurality of condensers and inductances and is complicated and voluminous, and its superiority in performance over the simple quarter wave transmission line is small.
  • the condenser at the same time series tunes the lower open end of the stub to the mean operating frequency and thus makes the impedance across the open or lower end of the stub or antenna zero at the mean operating frequency.
  • Figure 1 shows an antenna system according to the invention utilising an unbalanced antenna with respect to earth potential.
  • FIG. 1 shows an antenna system according to the invention utilising a dipole or balanced antenna and transversely arranged transmission line.
  • Figure 3 shows a supporting arrangement for the antenna system shown in Figure 2.
  • Figures 4, 5 and 6 show a dipole antenna system according to the invention with the-transmission line coaxial with the dipole antenna.
  • Figures 5 and 6' are partial views showing modified connections for use with a concentric and twowire transmission line respectively.
  • Figures '7 and 8 show supporting arrangements for the antennasystems of the type shown in Figures 4, 5 and 6.
  • the reference numeral I indicates the hollow conducting cylinder which is closed at its upper end 2 and has a conical lower end 3 tapering towards the ground or earth plane indicated at 4.
  • the antenna is enclosed in an insulating tubular casing 5 and held in position therein by means of asupporting bushing 6, for example, of polystyrene located substantially at the voltage node on the cylinder I and this tubular'casing is supported directly on the earth plate 4 but holds the antenna I insulated from the ground.
  • the central conductor is shown at 1 its upper end to the closed end 2 of the hollow conducting'eylinder I, and passes through the lower conical end at which, if necessary, a low capacity centring insulator may be used; 8 indicates the transmission line for connection to a translating device.
  • the quarterwave line impedance transformer is. indicated at H) connecting the transmission line 8 to the antenna I.
  • the cylindrical hollow conductor I has a physical length of less than half the mean operating wavelength.
  • the central conductor 1 together with the hollow conductor I closed at its upper end forms a short circuited stub having an electrical length between one-quarter and one-half the mean operating wavelength.
  • This stub is tuned to resonance at substantially the mean frequency of the operating band by parallel tuning the upper closed end of the stub by means of an adjustable condenser I I accommodated within the. hollow cylindricalmember I and connected parts are given the same frequency about the mean operating frequency to an extent that matches the unsymmetrical reactance characteristic of the antenna with respect to the mean operating frequency.
  • the characteristic impedance of the stub is chosen for example, by suitable diameter of the central conductor so that the reactance seen across its open end is equal and opposite to the reactance at the base of the antenna, that is, of the hollow cylindrical member alone, at frequencies near the outer limits of the operating frequency band.
  • the insulating casing 5 provides a weather screened space around the antenna and weather conditions have a reduced and more uniform effect on the performance of the antenna over the operating frequency band than one which is not screened.
  • the single matching transformer I0 may be replaced by two matching transformers in series of characteristic impedances ZI and Z2 respectively such that R, Zl, /ZIZ2, Z2, and Z0 are in geometrical progression, where R is the mean resistance of the antenna, and Z0 is the characteristic impedance of the transmission line. This arrangement would provide a slight improvement in performance over the single transformer.
  • a dipole antenna comprises two members as described in connection with Figure I placed with their conical ends 3-, S'adjacent each other and the transmission line comprises two coaxial transmission lines, but may be a two wire screened transmission line, brought horizontally to the two conical ends of the hollow conducting cylinders and. each is coupled to its respective central conductor 1, 1' of the two members through a quarter wave line impedance transformer I0; I 0' of suitable characteristic impedance as described in connection with Figure 1. (It should be understood that screened lines are here recommended'for ease of mounting in such cases as ship installations but an unscreened balanced transmission line may be used.)
  • the two dielectric cylinders 5, 5 are identical to each other.
  • the balanced: or twovwire-screened transmisquired on the outer screen of the transmission line is of great value when the: antenna: is to operate over a wide frequency band and renders the dipole antenna describedthe simplest and'best balanced antenna in, regard to performance throughout the operating' nequency-band.
  • the central conductors of the quarter wave line transformer where a concentric line is used (Figs. 4 and 6) or one of the conductors of a two wire line (Fig. 5) is connected to the central conductor I of the upper cylindrical member.
  • the other wire is connected to the outside of the lower cylindrical member I as shown at 16 and in the case of the coaxial line (Figs. 4 and 6) the outer conductor of the quarter wave line transformer is connected to the apex of the conical end of the lower cylindrical member I as shown at I1 (Figs. 4 and 6).
  • a low characteristic impedance antenna is an advantage as it allows a relatively high impedance suppressing stub to be constructed.
  • conneotxsuppresson stubs tunedztoa and inequen'ciesof; the frequency bandiatpositions along the fee'ddinedetermined:experimentally, but simplicity would probably dictate-a compromise such.
  • the short circuiting device the form of adisc annulus, should lee-thin and a relatively low. character istic impedance antenna usedso' that the i-mr pedance of the blocking stub will benign.
  • a dipole radio antenna system having a substantially constant resistance over a broad operating band of ultra high frequencies
  • a dipole antenna comprising two hollow con ducting cylinders each having a physical length between one quarter and one half the mean operating wave length and half wave resonant at the mean operating frequency, a central conductor which extends through the length of one of said hollow cylinders and is connected to one end thereof forming a stub therewith, a central conductor which extends through the length of the other of said hollow cylinders and connects with the inner side of said cylinder forming a stub therewith, a reactance element connected between said central conductor and said cylinder at a point intermediate the ends thereof for tuning said stubs to resonance at the mean operating frequency, a transmission line for coupling the antenna to a translation device and an impedance transformer substantially a quarterwave length of said mean frequency coupling the open circuited end of said antenna and said transmission line,
  • a radio antenna system having a substantially constant resistance over a broad operating band of ultra-high-frequencies including an antenna comprising a hollow conducting cylinder having a physical length between one-quarter andone-half of the mean operating wavelength and half wave resonant at the mean operating frequency, a central conductor extending through said hollow cylinder connected to one end thereof and forming therewith a, stub, the outer end of said vertical cylinder being closed, said cylinder having a reactance element connected between said central conductor and said hollow cylinder at a point intermediate the ends thereof for parallel tuning to resonance at the mean frequency.
  • said reactance element also series tuning the other portion of said cylinder and central conductor to substantially the mean frequency and forming a quarter wave stub of said other portion, thereby making the impedance across the open end of the stub substantially zero at the mean operating frequency; a transmission line for coupling said antenna to a translation device and a quarter wave line impedance transformer at substantially said mean frequency coupling said antenna and said transmission line.
  • a radio antenna system as claimed in claim 3, said reactance element comprising an adjustable capacity connected across the said cylinder and the central conductor. 7
  • a dipole antenna system having a substantially constant resistance over a broad operat ing band of ultra-high frequencies including a dipole antenna comprising two hollow conducting cylinders each having a physical length between one quarter and one half the mean operatin g wave length and half wave resonant at the mean operating frequency, two central conductors, one extending through the length of each of said hollow cylinders and connected to the ends thereof to form a short circuited stub therewith and two reactance elements; one being connected between each of said central conductors and said cylinders at a point intermediate the ends thereof for tuning said stubs to resonance at the meanoperating frequency, a transmission linefor coupling said antenna to a translation device and an impedance transformer substantially a quarter 5 wave length of said mean frequency coupling the open circulted end of said antenna and said trans-- transformer being accommodated within one of said conducting cylinders and further including means for suppressing standing waves on the transmission line.
  • a radio dipole antenna system as'claimed claim '7 said means comprising a short circuiting conductor between the screen of said balanced transmission line and said one cylinder at substantially a quarter of the mean operating wave length from the inner end of said cylinder.

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  • Variable-Direction Aerials And Aerial Arrays (AREA)
  • Details Of Aerials (AREA)
US573099A 1943-11-05 1945-01-16 Radio antenna Expired - Lifetime US2480172A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB18436/43A GB579778A (en) 1943-11-05 1943-11-05 Improvements relating to radio antennae

Publications (1)

Publication Number Publication Date
US2480172A true US2480172A (en) 1949-08-30

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Family Applications (1)

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US573099A Expired - Lifetime US2480172A (en) 1943-11-05 1945-01-16 Radio antenna

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US (1) US2480172A (fr)
FR (1) FR932829A (fr)
GB (1) GB579778A (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2594055A (en) * 1949-06-29 1952-04-22 Westinghouse Electric Corp Antenna coupling system
US2624844A (en) * 1946-03-04 1953-01-06 Jessic A Nelson Broad band antenna
US2683808A (en) * 1947-02-17 1954-07-13 Shumaker Clifton Broad band antenna
US2750590A (en) * 1951-11-06 1956-06-12 Henry V Phelps Dipole antenna
US4109255A (en) * 1977-03-21 1978-08-22 Silliman Thomas B Omnidirectional broadband circularly polarized antenna
US4117493A (en) * 1976-12-22 1978-09-26 New-Tronics Corp. Radio antenna

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB260005A (en) * 1925-10-19 1927-03-24 Emil Geles Improvements in and relating to aerials for the transmission and reception of electro-magnetic waves
US2067337A (en) * 1932-08-12 1937-01-12 Telefunken Gmbh Antenna for submarines
US2158271A (en) * 1936-10-13 1939-05-16 Telefunken Gmbh Short wave antenna
US2167709A (en) * 1936-03-17 1939-08-01 Emi Ltd Wireless aerial system
US2226686A (en) * 1937-11-16 1940-12-31 Mackay Radio & Telegraph Co High frequency transmission network
US2239700A (en) * 1938-02-15 1941-04-29 Rca Corp Wide band short wave antenna and transmission line system
FR878564A (fr) * 1940-11-09 1943-01-25 Licentia Gmbh Antenne dipole tubulaire
US2311364A (en) * 1939-04-03 1943-02-16 Buschbeck Werner Broad-band antenna
US2321454A (en) * 1941-11-22 1943-06-08 Rca Corp Multiple section antenna
US2368298A (en) * 1942-07-11 1945-01-30 Republic Aviat Corp Aircraft structure

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB260005A (en) * 1925-10-19 1927-03-24 Emil Geles Improvements in and relating to aerials for the transmission and reception of electro-magnetic waves
US2067337A (en) * 1932-08-12 1937-01-12 Telefunken Gmbh Antenna for submarines
US2167709A (en) * 1936-03-17 1939-08-01 Emi Ltd Wireless aerial system
US2158271A (en) * 1936-10-13 1939-05-16 Telefunken Gmbh Short wave antenna
US2226686A (en) * 1937-11-16 1940-12-31 Mackay Radio & Telegraph Co High frequency transmission network
US2239700A (en) * 1938-02-15 1941-04-29 Rca Corp Wide band short wave antenna and transmission line system
US2311364A (en) * 1939-04-03 1943-02-16 Buschbeck Werner Broad-band antenna
FR878564A (fr) * 1940-11-09 1943-01-25 Licentia Gmbh Antenne dipole tubulaire
US2321454A (en) * 1941-11-22 1943-06-08 Rca Corp Multiple section antenna
US2368298A (en) * 1942-07-11 1945-01-30 Republic Aviat Corp Aircraft structure

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2624844A (en) * 1946-03-04 1953-01-06 Jessic A Nelson Broad band antenna
US2683808A (en) * 1947-02-17 1954-07-13 Shumaker Clifton Broad band antenna
US2594055A (en) * 1949-06-29 1952-04-22 Westinghouse Electric Corp Antenna coupling system
US2750590A (en) * 1951-11-06 1956-06-12 Henry V Phelps Dipole antenna
US4117493A (en) * 1976-12-22 1978-09-26 New-Tronics Corp. Radio antenna
US4109255A (en) * 1977-03-21 1978-08-22 Silliman Thomas B Omnidirectional broadband circularly polarized antenna

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GB579778A (en) 1946-08-15
FR932829A (fr) 1948-04-02

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