US3097358A

US3097358A - zamanakos

Info

Publication number: US3097358A
Authority: US
Publication date: 1963-07-09
Anticipated expiration: 1980-07-09

Description

July 9, 1963 A. s. zAMANKos Y 3,097,358

FUSE BEARING ANTENNA Filed Oct. 28, 1960 ARTHUR S. ZAMANAKOS BY MW aff ATTORNEY United States Patent() 3,097,358 FUSE BEARING ANTENNA Arthur S. Zamanakos, 2809 S. 8th St.,-Arlington, Va.

Filed Oct. 28, 1960, Ser. No. 65,867

Claims. (Cl. 343-119) (Granted under Title 35, U.S. Code (1952), sec. 266) must ordinarily 1be made between :the various desirable characteristics of the antenna system. For example, -for initial acquisition purposes it desired that the electromagnetic wave coupling system be sufficiently broad in anguiar coverage so as to be able .to pick up the source of electromagnetic waves and yet at the same time not be so broad as to possibly pick up an undesired source. Furthermore, once acquisti'on of the desired source of electromagnetic waves has occurred it is normally desired that the coupling dewcc have suitable -beamwidth characteristics so as to permit it 'to operate despite possible evasive tactics of the source of electromagnetic waves and yet not be misled by other -sources of electromagnetic waves. A further difficulty involved in such a passive homing device is the tremendous variation in signal intensity encountered as the hom-ing device moves from an initial` starting point, which normally is at considerable range from the source of electromagnetic ywaves, to the more highly intense fields existent in proximity to the source of electromagnetic waves. Homing devices ordinarily must employ one of various forms of signal comparison or lobring techniques whereby it is possible to determine whether the passive homing device is traveling in the proper direction toward the source of electromagnetic waves. Such determination also must normally be made in two planes where the passive homing device is opera'ble in a medium such that restriction to one plane of travel does not occur.

Because of the wide variation Vin signal .intensity encountered as noted in the foregoing, it frequently occurs that a passive homing device which has adequate sensitivity for initial phases of operation will :be overloaded long before the passive homing device reaches the source of electromagnetic waves. Such overload can be manitested in many ways and can have many different results n depending lupon the specific design Vof fthe apparatus. However, in general, it is expected where 'the source of electromagnetic waves is a powerful radio frequency device such as an enemy operated distant radar transmitter, that the passive homing device would employ several crystal detector devices in the initial stages thereof to perform the customary function of superheterodyne receiver mixing -in various comparison channels. In such a device overload normally is manifested most significantly Iby a burn-out .of 'the crystal mixer devices due to the application of excessive electromagnetic wave energy thereto as a result of proximity to the source of high powered electromagnetic wave energy.

By proper design of the receiver system, it -is possible for continued operation to be obtained even 'with the mixers reduced towhat would normally be considered a useless condition where low signal levels are involved. This is t-rue because the mixer function can be caused to transfer to a less sensitive mixer or some other subsequent stage which may have some inherent nonlineairity therein at high signal levels. Such a condition couldY ice normally occur in any more or less conventional receiver vdue to overdlri-ving of grid circuits, anode circuit cutoff and the like, all of which can produce non-linearity at stages subsequent to the normal mixer stage so that mixing action can be obtained to produce the superheterodyne frequency conversion.

In the superheterodyne system when the mixer crystals of comparison channels are overloaded and burn out, it is essential :that the burn-out of crystals in opposing zones of reception occur simultaneously, otherwise the channels associated with the two opposing zones of -reception will have drastically different characteristics, one having a seriously deteriorated crystal mixer and the other a still operable crystal mixer. This situation is likely to cause sen'ouslyrerroneous guidance information to be derived by the homing device causing it to veer sharply away from the direction of the sou-ree of electromagnetic waves upon which it is homing. It is thus seen that it would be desirable to provide asystem arrangement wherein such unequal disablement of opposing comparison channels is avoided and also where if possi-ble mixer crystal burn-out could also =be retarded.

It is accordingly an object of the present invention to provide such a system in which the unequal burn-out of mixer crystals may be avoided. v

Another object of the present invention is to provide a system wherein the strength of signals applied to a receiver in a passive homing device is automatically reduced as extremely high levels signal lintensity are encou-ntered.`

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 drawings wherein:

FIG. -1 shows a typical embodiment of the features of the present invention.

FIG. Z shows in greater detail the configuration of a typical antenna system embodying the principles of the present invention.

FIG. 3 shows typical details of a fusible link employed in Ithe present invention.

With reference now to FIG. 1 of the drawing, the apparatus shown -therein contains a more or less distant source of electromagnetic wave energy 10 which may produce any conventional form of emission and which would normally be entirely independent of the balance of the apparatus of FIG. 1 which is a schematic representation of a passive homing device such as a guided missile identified in general by the numeral 11. This device 11 will ncrmally contain some suitable form of propulsion apparatus not within the basic teachings of the present invention as to specific details of improvement thereof and in addition will contain some form of guidance device which is operated upon by apparatus of the present -invention as contained within the block 12 which is labeled guidance and control apparatus. Normally the guidance and control apparatus wouldv be accomplished by the operation of suitable aerodynamic surfaces or selective operation or direction of rocket motors and the like, to provide for sending the passive homing device 111 in the desired direction which is that of the distant signal source 10. For guidance purposes in each plane in which the passive homing device 11 can be maneuvered, the device 11 has a pair of matched signal reception channels with suitable arrangements for comparing the signals received -by said channels to determine if any correction is necessary to keep the passive homing device 11 traveling in the direction of the distant signal source 10. As typiiied in FIG. 1 these channels contain the receiving channel No. 1 apparatus 13 and receiving channel No. 2 apparatus 14 each of which will kordinarily because of the frequencies involved in most typical situations contain as :the rst stage thereof a crystal mixer device, such .an arrangement being well known in the art employed in radar systems for example. 'Ihe output from -the

receiver channels

13 and 14 is compared in a suitable comparison circuit 15, which is not of any great specific importance in the present exempliiication of the invention, by means of which the receiver output is compared for the operation of the guidance and control circuits y12. Each receiving

channel

13 and 14 has a suitable antenna 16, 17 for interception of electromagnetic wave energy from the distant signal source 10.

In accordance with the basic .teachingsof the present invention the antennas 16 and 17 are constructed in such a manner as to include self detuning or desensitizing devices of the nature of fuses which burn out simultaneously upon the attainment of a preselected antenna current to reduce the antenna dimensions in such a way as to also reduce .the mixer current and hence avoid burn-out of mixers incorporated within the

receivers

13 and 14. When the antenna detuning devices are constructed i-t is possible to obtain precise control over Ythe fusing characteristics because 'this fuse device has yonly one function to perform, as contrasted to the more or less fortuitous burn-out of a mixer device,l which is normally selected only for its capabilities of providing desirable mixing characteristics and not also upon a basis of its burn-out current which could not be determined precisely in any event except by the destruction of the unit. The fuse art has progressed to a state wherein it is possible to obtain precisely controlled current burn-out characteristics for a plurality of units.

In a typical embodiment the specific antenna could be of any suitable form desired such =as a dipole or the like. However, the spiral antenna has certain advantages which render it very desirable in connection with the apparatus of the present invention. The spiral antenna has broad characteristics not only with regard to frequency of operation but also with regard to beamwidth. Thus the spiral' antenna provides the desired broad angle of reception for initial capture or location operation. As a result of the broad frequency characteristics it is capable of receiving signals over -a wide frequency range without serious impedance matching problems. It does have certain general limitations "however with regard to the periphery thereof and its relationship to the frequency of operationv for maximum efficiency. Howeverin this instance the eiciency is varied by incorporating into the conductors of the spiral antennas

fusible elements

22, 23 arid 24, 25 which are designed to burn out when a desired magnirude of antenna current in the elements is reached.

The spiral antenna elements may be described in greater detail as being two conductor archemedian spirals disposed in a plane in which the conductors spiral outward from a central portion of small diameter to a large diameter outer portion. Connection rto the two conductors is by means of

suitable lead wires

26, 27 and 28, 29. Typically fthe spiral antennas may be produced by printed circuit techniques wherein the spiral conductors remain as ribbons of conductive material on a suitable printed circuit base member which is selected for its insulation and strength properties. The

fusible elements

22, 23 and 24, 25 may be constructed of some suitable resistance wire, and preferably are encapsulated to minimize the deterioration effects of time, heat, humidity and the like. Typically =the fusible elements are selected in such a manner as to have precisely matched bum-out characteristics and are connected across purposely placed discontinuities in the conductors of the spiral elements.

When the spiral antenna elements are used prior to burn-out of the

fusible members

22, 23, 24 4and 25, the elements have continuous conductors so that the normal gain characteristics of the spiral antenna are experienced. As the passive homing device 11 approaches the signal source however, eventually a point is reached lat which the signal becomes so intense that the current in the antenna conductors 16 and 17 exceeds the capabilities of the fusible members, at which point burn-out occurs and the outer portions of the spiral antenna element conductors are no longer connected to the lead in

conductors

26, 27, 28 yand 29. This reduces .-the effective periphery of the spiral antenna element lto a small portion of the previously existing condition which by selection as to size on a trial and error basis or by calculation reduces the lsensitivity of the spiral antenna element without producing a substantial undesired variation in the impedance charatceristics of the use exemplified herein. Thus the signal applied through the

leads

26, 27, 28

and 29 to the

receiving channels

13 and 14 is reduced in amplitude so that burn-out of the crystal mixers will not occur. Thus the passive homing device 11 is permitted to travel to the distant signal source 10 without the danger of nonsimultaneous burn-out of crystal mixers in the 4receiving, channels 1 and 2.

From the foregoing it is apparent that considerable variation in the specific structure shown is possible without exceeding the principles of the present invention. For example, the -invention as described is not limited to the typical spiral antenna nor is it limited to devices employing single spiral antennas for the receiving channels No. 1 and No. 2. Specifically the spiral antenna elements employed singly -for each channel as in FIGS. l and 2 are circular polarization sensitive devices which in some instances may not be altogether desirable particularly if the distant signal source 10 is of such a nature as -to produce linearly polarized signals, in which instance yan antenna system for the passive homing device 11 would be desired having linear polarization characteristics. Where lsuch is encountered it -is also within the teachings of the present invention -to employ a plurality of antenna elements for each channel, fthe antenna elements being in the form of spiral doublets having linear polarization characteristics. In such an instance fusible mem-

bers

22, 23, 24, 25 would be employed in each conductor of each spiral antenna element.

As a fur-ther exemplification of the variations possible with the apparatus of the present invention, in some instances it may be desirable to apply a deliberate signal lfrom within the passive homing device 11 to cause the A burn-out of the various

fusible members

22, 23, 24 and 30, 31, 32 and 33 whereby a disabling signal may be applied to 'all fusible members simultaneously from a disabling circuit 34 responsive to the signal level in the

yreceiving channel

13 or 14. Thus when the signal level in the receiving

channel

13 or 14 for example reaches a selected level Ias sensed by any suitable form of measuring device, a signal is delivered to the disabling circuit 34, which may be a suitable threshold circuit and amplier, which is then applied through the radio

frequency isolating devices

30, 31, 32 and 33 to cause the simultaneous destruction of all of the

fusible members

22, 23, 24 and 25.

FIG. 3 exemplifies .the manner in which the

fusible elements

22, 23, 24 and 25 may be constructed so as to be responsive to such va simultaneous destruct signal. As shown the fusible member contains la central wire 50 which is the heat fusible element having terminals 51 and 52 which connect the particular spiral conductor asso-` ciated therewith. 'I'he fusible member 50 is contained within a suitable encapsulation 53 which may have suitp passage of antenna current therethrough, will cause a burn-out of the .fusible member 50. Typically one of the leads 55 would `go to the control lead of the disabling circuit 34 whereas the other lead 56 could go to the ground return of the disabling circuit 34.

`Obviously many modications and variations of the present invention are possible in thevlight -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 descri-bed.

What is claimed is:

1. A signal energy coupling system comprising, a plurality of antenna components cooperative for high sensitivity with at least one component operative individually at lesser sensitivity, a radio Afrequency operative device, means connecting one of said antenna components to the radio frequency device, and current responsive means connecting said antenna components whereby connection between said antenna components is broken yupon the occurrence of preselected current therethrough.

2. A signal energy coupling system comprising, a spiral antenna having a discontinuity in at least one conductor thereof, a radio frequency -operative device, means connecting said spiral antenna to `said device, and current responsive means for bridging the -discontinuity in the spiral antenna whereby the connection across the continuity is broken upon the `occurrence of preselected current flow therethrough. f

3. In apparatus for homing on a source of electromagnetic wave energy, means for comparing two incoming signals :to determine errors of homing, a plurality of antenna components cooperative in pairs for high sensitivity with at least one component of each pair operative individually at reduced sensitivity for deriving the two incoming signals, means connecting .a irst lone of each pair of the antenna components to said first named means,

and fusible current responsive disconnect means connecting the second of each pair of antenna components respectively to the iirst one of each pair of antenna components whereby greater overall signal coupling to the means for comparing is obtained until preselected current is realized due to proximity of the apparatus to the source, causing destruction of the fusible current responsive means.

4. In apparatus for homing on a sou-ree of electromagnetic wave energy, a plurality of spiral antennas having a discontinuity in at least one conductor thereof, means for amplifying signals picked up by the antennas, means for comparing amplied signals from two of the antennas to derive guidance control signals for the homing apparatus, and current responsive disconnect means for bridging the spiral antenna discontinuity whereby the connection across the discontinuity is broken upon the occurrence of preselected current flow therethrough.

5. In apparatus for homing on a source of electromag-l netic wave energy, a plurality of spiral 'antennas having, a discontinuity in at least one conductor of each, means for amplifying signals picked up -by the antennas, means for comparing amplified signals from two of the antennas -to derive guidance control signals for the homing apparatus, a plurality of current responsive disconnect means for -bridging the spiral antenna discontinuities whereby .the connections across the discontinuities are broken vupon the occurrence of preselected current ilow there- References Cited in the le of this patent UNITED STATES PATENTS McNatt May 12, 1959 Mueller Nov. 28, 1961

Claims

5. IN APPARATUS FOR HOMING ON A SOURCE OF ELECTROMAGNETIC WAVE ENERGY, A PLURALITY OF SPIRAL ANTENNAS HAVING A DISCONTINUITY IN AT LEAST ONE CONDUCTOR OF EACH, MEANS FOR AMPLIFYING SIGNALS PICKED UP BY THE ANTENNAS, MEANS FOR COMPARING AMPLIFIED SIGNALS FROM TWO OF THE ANTENNAS TO DERIVE GUIDANCE CONTROL SIGNALS FOR THE HOMING APPARATUS, A PLURALITY OF CURRENT RESPONSIVE DISCONNECT MEANS FOR BRIDGING THE SPIRAL ANTENNA DISCONTINUITIES WHEREBY THE CONNECTIONS ACROSS THE DISCONTINUITIES WHEREBY UPON THE OCCURENCE OF PRESELECTED CURRENT FLOW THERETHROUGH, AND MEANS FOR APPLYING A DESTRUCT SIGNAL TO SAID DISCONNECT MEANS TO CAUSE THE CONNECTIONS THROUGH ALL OF SAID DISCONNECT MEANS TO BE BROKEN SIMULTANEOUSLY.