US3069113A - Antenna system for an ordnance missile - Google Patents

Description

Dec. 18, 1962 R. DE WlTT HUNTOON 3,069,113

ANTENNA SYSTEM FOR AN ORDNANCE MISSILE Filed April 10, 1959 A fi 9 I 4 QSCILLATOR 2 DETECTOR 9| INVENTOR.

ROBERT D. HUNTOON ATTORNEY5.

T he

rates tent ANTENNA SYTEM FOR AN ORDNANQE MESSILE Robert De Witt Huntoon, Kensingtcn, Md, assignor t the United States of America as represented by the Secretary of the Navy Filed Apr. it 195d, Ser. No. 365,645 4 Gaines, (Cl. 244--14) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to radio antennae, and particularly to the use of a plurality of antennas on a single ordnance missile as in an antenna system for radio controlled proximity fuzes.

This application is a continuation-in-part of the application of Robert D. Huntoon, Serial No. 522,287, filed February 14, 1944, and now abandoned.

The primary objective of the instant invention is to provide improved polarized transmitting and receiving antenna means so arranged that the longitudinal body of the ordnance missile is of metal and forms a part of one of the antenna elements adapted to act as a radiator, while a separate receiving aerial, also carried by the body, is of such directional characteristics that it does not respond effectively to direct radiation from the transmitting area, but is responsive to energy reflected from the target as the latter is approached.

An object of this invention is to provide a plurality of antennas from a single ordnance missile to serve as an antenna system for radio-controlled proximity fuzes wherein the body of the ordnance missile forms at least a part of the radiating system and is polarized longitudinally substantially in the direction of travel, while a transversely polarized receiving antenna system is carried by the nose of the missile in such a manner and position that it cannot respond efliciently to the transmitted (longitudinal) radiation, but effectively receives a reflected ener A more important and specific object of this invention is to provide an antenna system for a radio-controlled proximity fuze of an ordnance missile that receives by direct coupling a local signal of the transmitted radiation having the proper magnitude for mixing, with the reflected signal received to create a beat frequency for functioning the fuze. A beat will be obtained by mixing the local and reflected signals since the reflected signals will have a frequency which differs from the local signal (or transmitted signal) by where V is the velocity of approach of the missile toward the reflector for the transmitted energy and A is the wave length of the transmitted radio energy.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIG. 1 is a side elevational view of a bomb provided with a compound antenna system constructed and arranged in accordance with the present invention; and

FIG. 2 is a view on a larger scale centrally broken away, showing the bomb in side elevation and the antenna means in longitudinal section.

Referring now to the drawing wherein like reference numerals denote like or similar parts throughout the several views, reference character 1 designates the body of a bomb shown of generally conventional form and provided with fins 2, although it will be apparent that the invention is not limited to the details of the bomb construction and may in fact be applied not only to missiles of various forms but to other moving objects, including those commonly classified under the term vehicle.

' An oscillator 4 Within the bomb body may comprise the source of radiant energy, and excites the metallic casing longitudinally, being connected to the bomb at some optimum point as 6, and the tail cap 7 which serves as a counterpoise. The tail cap 7 is carried by insulating post 8. Dipole receiving antenna rods 9 and 9' are transversely carried by the insulating cup 10 attached to the nose, the rods being connected to the detecting means 12, which is diagrammatically illustrated and may, as shown, be housed within the cup. The receiving antenna system thus constituted is not only so polarized that there is minimum pickup of transmitted energy, but also, the receiving system is partially protected by the divergent radiation pattern of the longitudinally excited bomb.

Due to the movement of the bomb with respect to the reflector (target), the reflected energy received by the dipole is of a different frequency from the small amount of transmitted energy which the dipole also absorbs. A beat frequency is thus established, providing greater response than would otherwise be possible.

During the time the bomb is in flight, the oscillator 4 will excite the bomb and electromagnetic waves will be radiated from the bomb surface in a pattern directly forwardly of the bomb at an angle to the longitudinal axis of the bomb. The electromagnetic waves produced by the oscillator 4 are radiated in a substantially symmetrical pattern around the circumference of the bomb due to the currents produced thereon. The body of the bomb thus acts substantially as a single radiating anten na along its longitudinal axis, which is perpendicular to the receiving dipole elements 9 and 9'. A typical radiation pattern of the desired forward directed variety may be produced by using the body of the bomb as a long radiating antenna, that is, having an effective length of several wave lengths, and illustrated by the radiation pattern 15 in FIG. 1. This forwardly directed pattern 15 would be essentially conical in shape and have a polarity on opposite sides of the bomb as indicated by the polarity vectors 13 and 14. It may be seen from these polarity vectors 13 and 14- that only a small component thereof 13' and 14 is polarized such as to be received by the dipoles 9 and 9 and that these components 13 and 14' are opposite in phase. The major portion of the transmitted energy 13" and 14 in the vicinity of the dipole elements is cross polarized with respect to the dipole elements. If the radiation pattern of the bomb were perfectly symmetrical, and if the dipoles 9, 9' were perfectly constructed, the receiver 12 would not receive a signal directly from the bomb radiation even though the radiation would be received by antenna-rods 9 and 9'. In this case, the energy received by the two sides of the dipole would cancel out. Actually the wave pattern is not exactly symmetrical due to small irregularities in the body of the bomb and the unequal excitation of certain portions thereof, and the rods 9 and 9' are not exactly alike so that under operating conditions, the receiver 12 will receive a signal of the same frequency as that radiated from the bomb but of reduced amplitude.

As the projectile approaches the target, the energy radiated by the bomb will be reflected by the target and a portion of this reflected energy will be picked up by the antenna rods 9 and 9. Since the bomb is moving relative to the target, the frequency of the reflected energy will be different from the frequency pickup by antenna rods 9 and 9' directly from the bomb radiation. A beat frequency will therefore result in the dipoles 9, 9 which can be detected by detecting means 12 in order to trigger the missile.

It is desirable that the amplitude of the wave energy received directly from the bomb be two to three times greater than the amplitude of the reflected wave in order that the beat frequency can be properly determined by detecting means 12. The amplitude of the energy received directly from the bomb can be adjusted, as will be apparent to those skilled in the art, by purposely varying the imperfections of the dipoles 9, 9, i.e. either of the antenna elements 9 or 9 may be made slightly longer than the other thus extending a greater portion thereof into the radiation pattern to receive a greater amount of the like polarized component of the transmitted energy, or the composition of one may be slightly different from that of the other thus changing the effective impedance.

thereof allowing only a different amount of power to be received by the detector 12, etc.

A novel wave transmitting and receiving system for a missile is thus provided whereby a beat frequency can be developed from the reflected frequency and transmitted frequency. The substantially symmetrical radiation pattern from the bomb makes possible the reception of the transmitted frequency at a reduced amplitude by the dipole on the nose of the projectile. The reception of the transmitted wave at reduced amplitude is also aided by the fact that the pair of dipole arms will not be perfectly symmetrical about the bomb axis due to errors in positioning or to a difference in length between the two arms. Since the amplitude of the transmitted energy received by the dipole is of the same order as the amplitude of the reflected energy received by the dipole, a beat frequency can be detected for operation of the fuze.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An ordnance missile having a radio-proximity fuze comprising an elongated metallic body, a source of high frequency waves, means connecting said wave source to said body whereby said body acts as a wave transmitter having a radiation pattern projecting forwardly of said body at an angle to the longitudinal axis thereof, a dipole mounted on the forward end of said metallic body in an unsymmetrical position with regard to the radiation pattern of said transmitter to receive a first radio signal directly from said transmitter at reduced amplitude, said dipole receiving a second radio signal reflected from a target at a frequency different from the transmitted frequency, and a detecting means electrically connected to said dipole to produce a beat frequency from said first and second radio signals.

2. An ordnance missile having a radio-proximity fuze comprising an elongated metallic body, a source of high frequency waves, means connecting said wave source to said body whereby said body acts as a wave transmitter having a radiation pattern projecting forwardly of said body and at an angle to the longitudinal axis thereof, a dipole mounted on the forward end of said metallic body Within the radiation pattern of said transmitter, the arms of said dipole being dissimilar in order to receive a first radio signal directly from said transmitter at reduced amplitude, said dipole receiving a second radio signal reflected from the target at a frequency different from the transmitted frequency, and a detecting means electrically connected to said dipole to produce a beat frequency from said first and second radio signals.

3. An ordnance missile having a radio-proximity fuze comprising an oscillator and an elongated metallic body acting as a transmitter for radio energy, said metallic body having a radiation pattern projecting forwardly of said missile at an angle to the longitudinal axis of said missile, said radiation pattern being slightly unsymmetrical about said longitudinal axis, a dipole antenna mounted within said radiation pattern on the forward end of said metallic body with its arms approximately symmetrical about said longitudinal axis, a first radio signal of transmitted frequency and reduced amplitude received by said dipole as a result of the non-symmetry of said radiation pattern, a second radio signal of frequency different from said transmitted frequency reflected from a target and received by said dipole, and a detecting means electrically connected to said dipole for producing a beat frequency from said first and second signals to trigger said missile. 4. An ordnance missile having a radio-proximity fuze comprising an elongated metallic body acting as a transmitter for radio energy, an oscillator electrically connected to said metallic body and to a counterpoise insulated from said metallic body to supply energy to said ietallic body, said metallic body having a radiation pattern projecting forwardly of said missile at an angle to the longitudinal axis of said missile, said radiation pattern being somewhat unsymmetrical about said longitudinal axis, a dipole antenna mounted on the forward end of said metallic body within the radiation pattern of said transmitter, the arms of said dipole being positioned transverse to said longitudinal axis and being dissimilar, a first radio signal received from said transmitter at a reduced amplitude as a result of the unsymmetrical radiation pattern and the dissimilarity of said dipole arms, a second radio signal of frequency different from the transmitted frequency reflected from a target and received by said dipole, and at detecting means electrically connected to said dipole for producing a beat frequency from said first and second radio signals to trigger said missile.

References Cited in the file of this patent UNITED STATES PATENTS 2,311,435 Gerhard Feb. 16, 1943 2,629,865 Barker Feb. 24, 1953 2,645,769 Roberts July 14, 195.3

FOREIGN PATENTS 91,592 Sweden Feb. 24, 1938 OTHER REFERENCES Huntoon et al.: Generator-Powered Proximity Fuze, Electronics, pp. 98-103, December 1945.

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