US2671853A

US2671853A - Energy radiation apparatus

Info

Publication number: US2671853A
Application number: US274446A
Authority: US
Inventors: Hilmer C Lindahl
Original assignee: Raytheon Manufacturing Co
Current assignee: Raytheon Co
Priority date: 1952-03-01
Filing date: 1952-03-01
Publication date: 1954-03-09
Anticipated expiration: 1971-03-09

Description

March 9, 1954 H. c. LINDAHL 2,671,853

ENERGY RADIATION APPARATUS Original Filed March 18, 1947 //v vE/vTore /7 23\ AIM MEI? C. L "van HL F'IG. 5V A NEV Patented Mar. 9, 1954 ENERGY RADIATION APPARATUS Hilmer C. Lindahl, New York, N. Y., assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Continuation of application Serial No. 735,435,

March 18, 1947.

1952, Serial No. 274,446

2 Claims. 1

This invention relates to means for radiatin electromagnetic energy and more particularly to such means adapted to direct and focus beams of electromagnetic radiation energy upon an energy absorbing body to thus produce predetermined patterns of energy or heat in the body thus positioned within operating range of the directing means.

This application is a continuation of application, Serial No. 735,435, filed March 18, 1947 and now abandoned.

The energy directing and radiating means of this invention has particular utility in therapeutic deep heating apparatus of the kind disclosed and claimed in the copending patent applications of Percy L. Spencer, Serial No. 732,451, filed March 5, 1947, and Henry F. Argento, Serial No. 730,926, filed February 26, 1947, now Patent No. 2,567,757, granted September 11, 1951, wherein the use of electromagnetic radiations of a frequency in the microwav spectrum for the therapeutic deep heating of body tissues is described. As described in said copending patent applications, it is desirable to direct and focus the electromagnetic radiation energy of microwave frequency upon an energy absorbing body to thus produce predetermined pattern of heat energy at desired focused points in the body under treatment. In order to assure maximum efiectiveness of energy transfer between the radiating apparatus and body, it is also desirable to properly match the impedance of the radiating element to th terminating impedance of an average body to be treated and the impedance of the radiation source. In the copending Argento application, it is disclosed that the correct impedance matching above described is obtained for most practical operating conditions when the total impedance of the director and radiating element is such as to produce a standing wave ratio in air of within the range of 1.2 to 1 and 1.6 to 1.

It is therefore, an important object of this invention to provide means comprising a stub radiating element and a hemispherical combined reflector and radiating element for radiating electromagnetic energy and for producing a circular pattern of heat as induced in a body by the radiated energy absorbed by the body positioned in front of the director at a distance of approximately a wavelength or less from the director opening, the circular pattern of heathaving a diameter approximately equal to the maximum diameter of the director, thus providing for accurate focusing of the energy upon a body to This application March 1,

be treated and avoiding wasteful misapplication of energy to parts of the body that are not intended to be treated.

It is another object of this invention to provide a combined directing and radiating apparatus which may be generically referred to as a director for properly focusing and directing radiated beams of electromagnetic energy to produce predetermined patterns of heat energy in a body to be treated positioned within the directors operating range and having novel means to obtain additional capacitive reactanc and a total impedance for the director such as to produce any desired standing wave ratio in air which may preferably be within the range of .2 to 1 and 1.6 to 1.

It is yet another object of this invention to provide a radiation director comprising a radiating element combined with a reflecting element in such manner as to radiate and direct electromagnetic energy to predetermined areas of a body to be treated and for producing a, circular pattern of heat energy in the body, the heat pattern having a relatively cold spot in a known position approximately at the center of the area such that, with proper manipulation and positioning of the director, irregular surfaces of a body such as an elbow or knee may be treated to produce even heating of the body at the same predetermined depth beneath the irregular surface of the body.

Other objects and advantages of the invention will be apparent with reference to the following specification and drawing in which:

Fig. 1 is a view of the director in half-section along the axis of the matching stub and also showing diagrammatically a magnetron oscillator as a source of microwave electromagnetic energy;

Fig. 2 is a rear view of the director; and

Fig. 3 is a fragmentary section of a modified form of director.

Referring to Figs. 1 and 2 of the drawing, .the combined radiating element and reflector of this invention, hereinafter termed a director, is shown to be connected with a source of microwave energy which may, for example, be a magnetron oscillator. While the director of this invention is particularly suited for use in therapeutic apparatus and will be described in connection with such apparatus, it will be understood that the invention is not limited to such usage.

The director It is comprised of the hemispherical combined reflector and radiating element H together with a bullet-shaped metal radiating stub element [2. Under certain conditions it may be desirable to form the stub element l2 in an inverted conical shape or other form than bullet-shaped and also the reflector Il may be formed with a parabolic or other shape if desired under certain conditions. The stub. radiatin element. L2 is approximately one-quarter wave.- length in length and is adapted to extend through an opening l3 of the hemispherical reflector and; radiating element II. It Will be. noted. that, although the stub radiating element 12 does not contact the walls of the opening i3, it is, never,. theless, spaced very close thereto. Fastened. by brazing, silver soldering or other suitable expee dient to the rear of the hemispherical reflector and radiating element I l, whichmay hereafter be called the reflector II, is a metal bushing I' l having a bore in alignment with the opening I 3. Extending transversel through the meta1=bushe ing [4 and supported thereby is the metal sleeve t. cons itu in he out c du of amat h: ma tub eme t P si io n nt ica ly. within the matching stub sleeve I5 is, an inner me e/.11 o duc or LE w ch s. u por e n the necedreqn n ric e t qn by the t l o t plu it-th match n st b nd. It sho d e understq e hat heme alnlu 11 supp r n t e nner, QQnductor [G -and connecting it to the outer. metatsleeve [dislocated at a point of zero field nqten i lovith" e nectte the e rom g e icnereyin he t b ransmiss line. t w ll ow. beseenthatthestub radiating element 92 ex tend n hrou h. e. o e n s e d. t I ?c.to. theiinner,me aleondu lio t e m t hmastubl ;.end. pncr dthe e y A coupling collar I8 is used to connect the m chin tub l e eand inner-c ndu t n Hi to the, outer. and; inner, conductors, respectively, at; cne ndiofi acoaxial. cable I 9.. Theother. end

of; the; coaxial cable. I91. may: be connectedin a suitablelmannth tothe anode and output, loop of a.magnetronyoscillator 2 8 shown ,in diagrammatic form to. beepergizedirom asource of direct. ourrentJu-j whose.positiveterminalmay begrounded together. with, the, anode; of. the, magnetron. As showninjlia 2.-of; thedrawing, the. bushing It is 811mlpiOYidediv With metal. shaft. or extension 22% bymeanspj which.the directormay. he fastened to a suitable support for. positioning. it in the ,desiredmelation, to a body. t be treated- The director in may, if desired, be providedwith a protective cover. 23 of. Pliofilm. or. other suitable material which is,.transparent. to; the radiations produced but which. will. prevent body, contact. with the. stubrradiating. element l2; andirefiector |:I:. such-.aswould cause accidental. short. circuit, arcing. andsevere. burning.

Ikmay; be .desirable to. have a certain amount of reactance in the director I 0 in order to.v.pro.- vide a total impedance for the director such as will; producea standing wave. ratio in air of within the range of 1.2 to 1 and lifi to lfor theradiationsemanated. The director of thisinvention isprovided with the following described novelmeans of obtaining additional capacitive reactance suchas to produce a total impedance to obtain the desiredstanding wave'ratio in air. It willbe notedthat the stub-radiating element I-Z-which is approximately one-quarter wavelength in-lengthextends through the opening I3 more than zero. Such part of the active length of the stub 12 is closely spaced to the opening iii in the metal walls of the bushing I4, which bushing is electrically connected with the reflector ll. As will be seen in Fig. 1 of the drawing, the spacing in the. opening I3 is: substantially less than the. spacing. between the inner conductor I6 and the outer sleeve N5 of the matching stub so that the close spacing thus afiordcd in the opening 13 along. a. portion. of the active length of the stub ['2 is, in effect, a line transformer providing added capacitive. reactance' to the energy in the system and:givingatotalzimpedance for the director element. Iosuchas to.-give the desired standing wave ratio. Itshould be understood that the length of theportionof active length for the stub I2 is determined by the desired amount of additional reactance necessary to obtain the desired standing-waveratio. It is a particularly advantageous feature of this invention to provide for an additional capacitive reactance in the director as obtained in the. above manner in order to properly. match the director H); to thefiexible coaxial cable is, which cable hasa relatively large amount. of

: inductivereactance tomicrowave frequencies-0f.

the. electromagnetic energ which may be suppliedto the cable. Inthe; case of the therapeutic apparatus referred to, the frequencies used in; the microwave spectrummay be withinthe-range of 2.300 to,3300-megacycles.per second.

A somewhat modified form of the invention is shown in fragmentary. sectionby Fig. 3 of; the drawings. and the same; reference. numerals are usedto identify parts of l the. invention which are identical with thestructure-shown inFig. 1; of; the drawing. In the form-.oftheinvention-shownat Fig. 3., the reflector element-.1 I isiormed with, the opening, I3. drawninto an annular flangeway. thus.providingthe,wall-surfaces :25.- The matching. sleeve l5. may. thenbe silver. soldered. at 26' to the. endzof the-flange. 254:0 provide a. support,- forthereflector II from thematchingsleeve 5.. In thisconstruction, it willbe noted that. the: stub. radiating element l2; extends. through the opening. I 3 andthat. a portion. ofthe activelength of. the stub element-lain; close proximityv to the, innerv wall. oizthe: annular flange 25r of there flectingelement, ll. Thus the added capacitive reactancefor the, director. unit is obtained inithe; noveltmannenofi thisrinvention dueto suchlclosepositioning; of: an active-portion ofthe. stub ele-, ment; IL with the.metal.wall of the reflector II.

Againareferringto Figs. 1 and 2 .otthe. drawing, itxwill be.notedithat.the reflector element: H; may also bra/considered: aradiating elementzsince. it; is a connected to. one;v sides of. the. transmission. line represented by the. outermetal s1eeve-l5 of the. matchingrstub; which isrelectricallyconnected. to the outer conductor. otthe'coaxial cable-I9 In other. words, the director-l itcomprised of the reflector element lat; and-"stubfiradiating element- I 2 is, in efiect, a modified form of a folded -di'- pole antenna, although-the combined reflector and'radiator this actually quite difierentfronr the usual -di-pole-element since it -is-hemispheri-- cal -incontour. With the -reflector element l!= connectedas shown to oneside of" thetransmission line containingtheelectromagnetic energyto he radiated, and-with the-metal-bushing I4' also'electrically connected to the reflector II, it should be understood that the particular arrangement of the directorin-whichthe stub radiating element I 2 passes through an opening I 31 ofizthereflector H and;:i1r.closeproximity-to the metal :walls; Oiiithfi; bushing I his :efiectiveias a line transformer to provide additional capacitive reactance for the director H] such that its total impedance will produce the desired standing wave ratio in air. The novel manner of obtaining additional capacitive reactance as described is not limited to the specific combination with a hemispherical reflector l I as other shapes of a combined radiator and reflector could be used such as parabolic or cone shapes.

Considering Fig. 1 of the drawing, it will be seen that the stub radiating element I2 is positioned with its axis approximately parallel to the direction of travel for the radiations emanated. Such positioning of a stub radiating element 12 within a hemispherical, parabolic or similarly shaped combined reflector and radiator ll produces a novel pattern of generated heat within an energy absorbing body positioned in front of the director opening at a distance of a wavelength or less. It should be pointed out that in using the director of this invention for therapeutic purposes it is found that the closer the body is positioned to the director Hi, the greater is the heat produced in the body. The heat pattern produced by the director is circular in area and corresponds approximately to the diameter of the opening of the reflector II, which in one form of the invention may be 4 inches in diameter. Approximately in the center of such pattern of heat generated in a body positioned within the operating range of a wavelength or less from the director is also observed a relatively cold spot. The cold spot thus obtained in an energy absorbing body enables the director to be used for deep heat treatment of certain portions of a body having an irregular surface contour which may present portions of a body within the area of treatment at a shorter distance from the director than other portions within the area. For example, the human elbow shown in the drawing at 24 may be so positioned within operating range of the director I 0 that its surface contour closest to the director is coincident with the colder spot in the heat pattern obtained from the director. Thus the same average amount of heating may be obtained over the entire area of treatment of the irregular surface contoured body such as the elbow positioned within operating range of the circular pattern of radiated energy.

It should be understood that this invention is not limited to the specific embodiment described since equivalent constructions within the scope of the appended claims will occur to those skilled in the art.

What is claimed is:

1. Means for radiating electromagnetic energy comprising: a bushing having a transverse bore passing completely through said bushing and an axial bore passing partially therethrough and communicating with said transverse bore; a reflecting member mounted at one end of said bushing; a transmission line mounted in and passing completely through the transverse bore of said bushing; and a radiating stub member connected to said transmission line and projecting into said reflecting member through the axial bore of said bushing; said reflecting member comprising a portion of a sphere; and said stub projecting into said reflecting member a distance substantially equal to a quarter of the diameter of said sphere.

2. Means for radiating electromagnetic energy comprising: a bushing having a transverse bore passing completely through said bushing and an axial bore passing partially therethrough and communicating with said transverse bore; a reflecting member mounted at one end of said bushing; a coaxial transmission line mounted in and passing completely through the transverse bore of said bushing; and a radiating stub member threadedly connected to the central conductor of said transmission line and projecting into said reflecting member through the axial bore of said bushing; said reflecting member comprising a portion of a sphere; and said stub projecting into said reflecting member a distance substantially equal to a quarter of the diameter of said sphere.

I-IILMER C. LINDAHL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,281,274 Dallenbach et a1. Apr. 28, 1942 2,446,982 Pound Aug. 10, 1948 2,586,754 Wild Feb. 19, 1952 2,586,827 Karlson Feb. 26, 1952