US2350916A - Ultra short wave antenna system - Google Patents

Description

June 1944- J. F. MORRISON 59 ULTRA-SHORT WAVE ANTENNA SYSTEM Filed May 17, 1940 2 Sheets-Sheet 1 FIG! NORTH-SOUTH PANEL 8 2/ EAST WE/T PANEL f J -/NV'/V 0R By ,J. l-TMOR. ISON ATTORNE};

June 6,1944. 2 ,S N Q 2,350,916

ULTRAwSHORT WAVE ANTENNA SYSTEM Filed May 17, 1940 2 Sheets-Sheet 2' Fla; m2 o F762 3 1 L 2a 2' 1 28 21, L 27 27 r fi 7 F IG. 4.

7 TOHE lNVE/VTOR y 4. MORRISON -70 u saunas I 5 {lira LINE I2 0.70, W r0 LINE /2 M ATTORNEY Patented June 6, 1944 UNHTED STATES.

ENT O F CE Telephone Laboratories, Incorporated, New. York, N. Y,, a corporation of New York 16 Claims.

This invention relates to antenna systems and more particularly to antenna arrays for radiating or receiving waves having a relatively high frequency.

As disclosed in Patent 2,086,976, G. H. Brown, July 13, 1937, the so-called turnstile antenna unit comprising a pair of horizontal doublets arranged in space quadrature and energized in phase quadrature functions to produce non-directional radiation in a horizontal planefprovide d that the currents in the two doublets'are, as stated in the patent to Brown, equal. If the currents are slightly unequal, the theoretical directive characteristic, instead of being circular as illustrated by Fig. IV of the above-mentioned atent, will be elliptical; and if the currents are greatly unequal the characteristic may even resemble the wellknown hour-glass diagram whereby the held intensities at points equally distant from the broadcast antenna will vary greatly. Also, an array or stack of such turnstile units produces in the vertical plane, assuming equal currents in the several units, a low beam, and as shown by Fig. V of the aboveementioned patent, the gain increases With the number of turnstile units. It has been found, however, that the theoretical directive characteristic and the theoretical "gain are not realized in actual practice, primarily because mutual coupling and other factors cause the doublet antennas to differ in impedance with the result that the doublet currents vary greatly. Also, in practice, considerable difiiculty has been experienced during the Winter season in obtaining efiective radiation with antenna systems resembling that mentioned above because of frequent sleet accumulation on both the horizontal and vertical elements of the system. In addition, the sleet or ice load has on occasion mechanically impaired antennas of this type.

It is one object of this invention to improve ultra-short wave radio transmission and reception.

It is another object of this invention to secure, in actual practice, properly phased equiamplitude antenna currents in a multiple unit array for the purpose of improving the gain of the array.

It is a further object of this invention to provide means for removing sleet and static currents from the horizontal and vertical portions of a system such as a vertical array of horizontal radiators.

It is still another object of this invention to provide a rugged durable multiunit vertical antenna array comprising horizontal radiators.

According to one embodiment of this invention Application May 17, 1940, Serial No. 335,663

the north-south doublets constituting one vertical panel of the turnstile array are arranged in groups or sections of two'each, and the east-west doublets constituting. the other'pa'nel of the. array are similarly arranged. While the doublets are termed north-south and east-west, the

orientation of these doublets may not, of course,

coincide with the four compass directions. Separate transmission lines, hereinafter "termed panel lines, connect the doublets in the two panels to the same junction point on the main line'irom thetransmitter. More specifically, the

doublets in each section are connected through individual quarter Wave-length coaxial lines here.- inafter termed branch lines, to thesame point on the associated panel line; and the doublets'in adjacent sections of the same panel are 'connected to the panel line at points spaced a wavelength apart and electrically distant an even multiple or a quarter wave-length from themain li'ne junction mentioned above, whereby in each panel the radiators are properly phased and the current in all doublets has the same'amplitude.

Considering each doublet, the two radiators comprise hollow metallic tubes closed at one end. A high'resistanceconductor connects the'closed ends of the twotubes, the arrangement being such" that the two radiating tubesot each doublet and enclosed heater wire constitute a series 'cir' edit for the 'sleet melting current, and the inner surface of each tube andthe portion'of the heater 7 wir adjacent thereto constituted high impedance for radio frequency, whereby the radio frequency flows only on the outerradiating surface of the tube. The two vertically positioned coaxial quarter wave-length branch lines in each section are enclosed ina'grounded cylindrical vertical shield which is directly conne'cted to the outer conductor of the two branch lines at their junction point so -that the two" radiating tubes'ar'e each conhected'to ground through'a pathof low impedanc for frequencies otherthan the operating carrier and side-'bandirequencis for the purpose of draining or removing static currents. At the same timelthe impedance between ground and each ra'diatohi's relativelyhigh at the op e ating frequency. Als o,the several vertical shields are qorlinearly arranged and articulated to form a mast, and the mast is'preferably equipped with sleet-melting lines each comprising a copper tube enclosing a heater conductor and extending v'ei tically along the inner or outer mast surface.

The invention willbemore" fnllyuinde'rstood from a perusal of "the iollcwing'specification taken in conjunction with the drawings on which Fig. 6 illustrates certain mechanical features of l the embodiment illustrated by Fig. 5.

Referring to Fig. 1, reference numerals I'de'signate half wave-length horizontal antenna doublets each comprising two quarter Wave-length tubular radiators 2 and 3 colinearly arranged and 7 each having a closed end 4 and an open end 5. The north-south doublets are vertically spaced a half wave-length apart and are included in one vertical plane and the east-west doublets are similarly spaced in avertical plane perpendicularly related to the north-south vertical plane. The doubletslare so positioned that each northsouth doublet is included in a horizontal plane containing an east-west doublet and forms therewith a turnstile unitor subarray'fi. The doublets l in the'north-south' panel, except the top doublet, and the doublets in the east-West. panel, except the bottom doublet, are arranged, as is explained more fully below, in groups or central sections I, each comprising a pair of vertically spaced "doublets. just referred to are'included in an antenna end or half section 8. In the case of each doublet a high resistance heater wire 9 is positioned within radiators'2 and 3, and connected to the closed radiator ends 4.

Reference numeral I designates a source of radio frequency energy 'which is connected through a high frequency pass filter -I I and main line I2 to the input terminals I3 of the northsouth and the east-west panel transmission lines I4. Reference numerals I5 designate the output terminals of the panel lines 14 and numeral I6 denotes a 90V degree phase shifter included in the east-west panel line M; A low II'BQUGIICYOPdi-fi' The top and bottom doublets rect current sleet-melting source I I and associated low-pass filter I8 may be. connected by means ofyswitch I9 to the main line I2 and the panel lines I 4. In each panel, separate section lines 20 connect the panel line M to each centralv section I and; separate quarter wave-length branch lines 2I are included in each section between the doublets I and the output terminals 22 of the section line 20. The doublet in the top end sectionis similarly connected through a quarter wave-lengthline 2I to a separate section line 20 and the doublet in the bottom end section of the east-west panel is connected through a quarter wave-length line 2| either directly to the panel.

line or through a section line of negligible length.

The paths extending from terminal I3 to thevarious output terminals 22 of the section lines 20 each have a length equal to an even multiple of a quarter wave-length, the difference in length between the section lines 20 connected to adjacent sections in the same panel being one wavelength. One output terminal 22 of each section lin 20 is connected by connection 23 of negligible lengths and a cylindrical shield represented by conductor 24 to the ground 25. As described below and illustrated in Figsf'l and 6 all transmission lines are preferably of the coaxial type. Also, the branch lines are preferably enclosed b the-cylindrical shield mentioned above.

Considering the radio frequency operation, energy is supplied through filter II over lines I2 and I 4 directly to the section lines 20 in the north-south panel and through quadrature phase shifter I6 to the section lines 20 in the east-west panel. In each section 1 the energy flows from terminals 22 of the section line 20 in parallel through the branch quarter wave-length lines 2| whereby the two corresponding quarter wavelength radiators in each section I of each panel are energized in phase and the four radiators in each central turnstile unit or subarray 6 are energized in quadrature phase. In each end section 8, the energy from the section line 20 flows through the quarter wave-length line 2| to the radiators 2 and 3 of the single doublet I. Also, since the section lines 20 connected to adjacent sections in the same panel differ in length a wave-length, all corresponding radiators in the panel are energized in phase. Thus assuming the currents in the north radiator have zero, phase, the currents in the south. radiator, have 180 degree phase, and the currents in the east and west radiators have, respectively, either and 270 degree phases, or 2'70 and 90 degree phases,

as indicated on the drawings. As explained in Patent 2,086,976 mentioned above,'the quadrature energization of the quadrature radiators pro duces, assuming the currents are equal, a circular. horizontal directive characteristic. Since the electrical distance from terminals 22 ofeach section line 20 to the terminals I3 is an even. multiple of a quarter Wave-length, the voltage effec:

tive at the various sets of terminals. 22 in the sections of both panels has an intensity substantially equal to that of the input voltage at terminals I3. This follows from the fact that in the case of a line having a length equal to an even multiple of a quarter wave-length, the ratio of the input voltage to the output voltage is unity, as disclosed in the text-book Communication Networks. by Guellemin, V01. 2, page 65.

Referring now to Figs. 2 and 3, it will be shown that,.in accordance with one feature of the invention, the currents .in all doublets I in both panels of the system of Fig. 1 have thesame am-. plitude, regardless of the difference in impedance amongthe doublets. In each of Figs. 2 and 3, reference character E denotes a voltage of constant intensity and reference numeral 26 designates a transmission line across which the impedances 21,. each representing a doublet impedance, are connected. The impedances are connected to points 28 electrically distant from the source E aneven multiple'of a quarter wavelength, the character m on the drawing denoting. an even integer. In the schematic representation of Fig. 2 the doublet impedances 21 are connected directlyto the selected points as in the system of Patent 2,086,976 mentioned above but inv the system/of Fig. .3 theimpedances 21 are connected to the selected points 28 through individual branch lines29, each a quarter wavelength long, as in the system of Fig. l, the-reference letter 12- designating an odd integer. The impedances 21 in each of Figs. 2 and 3 are assumed to be differ'entas indicated by the reference'characters Z1 and-Z2. I a

As is apparent from the description of Fig. l-

given above the voltages at the points 28 in the systems of Figs. 2 and 3 are each equal. to the voltage of the source E and therefore'i'n each system the voltages at points 28 are equal toeach other; Also, sincethe'voltage of source E is by design constant the "voltages effective at points 28 are constant. In th system of-Fig. 2 the currents l and; I; flowing through the parallel. impedances 2 1; are, in accordance wit-h Ohms law, nQl; equal since these impedances are directly connected; to the line 26 and since the impedances Zi and Z -are unequal. On the other hand, the currents I1 flowing through the. two impedances 21 in, the system of Fig. 3 are equal, although these impedances; are different, since in the case of' a quarter wave-length line terminated by an impedance, the current through the terminating impedance is independent of the value of the termination impedance and remains constant provided the voltage input to the line remains constant. See the text-book Communication Network referred to above, page 65. Hence in the system of Fig. 1, regardless of the differences among the doublet impedances, the doublet currents are maintained equal in amplitude inasmuch as the voltages effective at all section line output terminals 22 are each constant and equal to the input voltage at terminals I3, and the input terminals of each doublet l are connected through a quarter wave-length line to its associated set of terminals 22. In practice, as already indicated, the doublet impedances ordinarily differ from each other because among other reasons no two doublets occupy the same physical position with respect to the other doublets and, considering any two doublets, the mutual coupling between one doublet and the remaining doublets is substantially different from the mutual cou pling between the other doublet and the remaining. doublets. Moreover, changes in impedance often occur after long continued use as a result of deterioration and sagging of the antenna elements.

Referring now to Fig. 4, the operation of the sleet-melting circuit and the balance-to-ground arrangement used in the system of Fig. 1 will be explained. The coaxialquarter wavelength lines 2! in Fig. 4 correspond in function to the similarly designated branch quarter wave-length lines in Fig. 1, the upper doublet l in Fig. 4 being connected to one line 2| and the lower doublet I being connected to the other line 2!. The input terminals of these branch lines are directly connected to, and in fact coincide with, the output terminals 22 of the section line 20 which, as explain-ed above in connection with Fig. 1, is connected to the high frequency source It and the low frequency source I1. Also, at the junction of the two lines 2!, the outer conductors of these two lines arev directly connected to the ground 25 through connection, 23 and the shield 33. Considered in a diiferent manner, the two lines 2| constitute a half wave-length line connected between the input terminals of the two doublets in the section, the section line 23 being connected to the mid-point of the half wave line and the mid-point of the outer conductor of the half Wave-length line being grounded.

In operation, considering one doublet of Fig. 4, sleet-melting current flows in series along one conductor of section line 23, one radiator 2, heater conductor 9, the other radiator 3 and then along the other conductor of section line 20 as indicated by the arrows 3| in Fig. 4. The radio frequency energy, however, supplied by the same section line 20 flows substantially only along the outer surfaces of the two radiators 2 and 3 constituting each doublet I as indicated by arrows 32, inasmuch as the inner surface of each quarter wave-length radiator and enclosed heater conductor constitute a short-circuited quarter wave! len th; l ne. lnotherw nds, at t e, operating frequeasy th impedance Z. E oo n into. e

ubular. radi o is. xce ne yhigh. In the case f; each doub et. the r e trhand radiator Sis onec e o c rrents; su h as; a c ur nt, a n a-irc ue icr other thanthe ope atin fre- 1 2 195 t und .5. hr h a con c ive. path of negligibl impedance comprising the outer conuctor Q ine c nect on .3; and sh e d. 30.

Thedeft-hand radiator 2 is also connected to.

hand radiator 2 and the ground 25 isrelatively h gh nc t i radi q s c ne t to t n e conductor or ungrounded side of; section line 20; an e m e a e. e w n t e rig ta dradiator'3. and groundv 25 is. relatively high inasmuch as the input terminal of this radiator is.

connectedto ground 25 through the outer conductor of branch line 21 which has a length of a quarter wavelength. Similarly, in the system of Fig. 1, sleet-melting current flows along the conductors 9 when the low frequency source I! is connected to the system by means of switch I9. The low frequency pass filter l 8 functions to block the flow ofhigh frequency energy to the low frequency source I! and the high frequency pass filter H. functions to blockthe flow of lowv frequency energy to the high frequency source II). The right and left-hand radiators 2 and 3 are connected together by conductor 9. and to ground- 2,5v for lightningand static currents. Also, the radiators 2 and 3 of each. doublet are connected through. a high impedance to ground, the radiator 3 v being connected through the outer quarter wave-length conductor of branch line 2 I and connection 23. to the grounded shield 24, whereby theradiators of all doublets are balanced to ground at the operating frequency.

The embodiment, illustrated bythe perspective views, Figs, 5 and 6, is the same as that illus-v tratedby Fig. 1 except that instead of separate section transmission lines 20 for the various sections 1, the alternate sections 1 are connected tothesamepanel line I4, Thus, referring to Fig. 5, the, north-south sections 1 are bridged across. the north-south panel line I4 at points 33 spaced: a wave-length apart, and the east-west sections. 1 are connected to the east-west panel line Id at points 33 spaced 2, wave-length apart whereby the corresponding radiators are energized in phase. As shown on the drawings, the electrical path from any pair of points 33 to the input terminals 1 3. is an even multiple of a quarter wave-length whereby the effective voltages at these points are equal and constant. As in the system of Fig. 1, the doublets are each connected to the associated panel line through a quarter wave-length branch line 2| and, in operation, the doublet currents remain constant irrespective of impedance variations, as explained tical tubes are each a half wave-length'long' and, in each section], each encloses or shields The shields the'two associated .branch lines 2 I. are articulated by sleeves and form a strong flag pole type supportingstructure 35, the doublets being attached through insulators 36 to the articulated grounded supporting structure. Hence the doublets are series excited andnot,

as in the system of the-Brown patent mentioned above, shunt" excited. Reference numerals 31 designate sleet-melting coaxial lines each comprising a copper outer conductor and a high resistance inner conductor. These lines extend longitudinally'along the vertical structure 36 and are connected to the low frequency sleet-melting source .11.

- Although the invention has been explained in connection with certain specific embodiments, it should be understood that it is not to be limited to these embodiments since other apparatus may be employed in successfully practising the invention. Moreover, while the antenna of the invention is especially suitable for use with ultrashort waves as, for example, waves having a wave-length less than twelve meters, it may be" ing a length equal to a half wave-length or an odd multiple thereof, a translationdevice, a phase shifting means, and separate transmission lines connecting the mid-point, of the first line directly, and the mid-point of the. second line through said means, to Said device.

2 .;nsystem in accordance with claim flpsaid last mentioned transmission lines each having an electrical length equal. to an even multiple of a quarter wave length. j q 7 a,

3-. In a radio system,,a turnstile array comprising at 'le,ast three vertically spaced subarrays each comprising, two perpendicularly related horizontal doublets', a first half wave length branch line connectingone pair of correspondingdoublets.of the" central subarray and the uppermost sub-. array, a second half wave-,len'gth branch line connecting'the otherdoublet in,the centnalsubarray and the corresponding doublet in the remaining subarray, a translation device, a quadrature phase shifter, a first transmissionline connectingsaid device directly to the midpoint of one branch linefland a second. transmission line connecting said device through the phase shifter to themidpoint of the other branch line.

*l. .A system in accordancewith claim 3, said lastsmentioned transmission lines each having .a.

length equal to ,an evenimul tiple of-aquarter wave-length, 1..

,,5. In a radio, system, aturnstileantenna array comprising," a ,j plurality of. horizontal doublets spaced. 'aj'half .lwave-length apart-in a vertical. plane and constitutingafirst antenna'panel, a

second piuralityof horizontal vdoublets spaced a halfv wave-length apart in another, vertical plane and jconstituting, .a :secondanter1ria panel, each doiible'tbf'one panel and a doublet of'th'e other panel -beingincluded in the-same horizontal plane and constituting a subar-ray, aplurality of half wave-length vertical-branch lines each included between a different pair of adjacent subarrays and connecting one pair of similarly oriented doublets in said subarrays, the alternate branch lines being connected to doublets of the same panel, a translation device, a quadrature phase shifter, a panel line connecting the mid-points 1 of one of said alternate branch lines directlyto said device, and another panel line connecting the mid-point of the-remaining set of branch lines'through said quadrature phase shifter to said device.

. -6. -A system in accordance with claim 5, the

mid-points of the branchlines in each set being connected directly to the panel line at points spaced a Wave-length or a multiple thereof apart.

'7. A system in accordance with claim 5, separate section lines of different length connecting the mid-points of the branch lines in each set to the same point on the main line, the difference in length between the section lines associated with adjacent branch lines being one wavelength or a multiple thereof.

' 8. A system in accordance with claim 5, supporting and shielding means for said system comprising a plurality of articulated metallic tubular members, each member enclosing a difierent vertical half wave-length branch line and attached to the similarly oriented spaced doublets connected to said branch line.

9. In a radio system, an antenna member comprising two cylindrical tubular elements each a quarter wave-length long and each having an open and a closed end, the open ends of said elements facing each other, a high resistance conductor coaxially positioned within said elements and connected to the closed ends of said elements,

each element and the enclosed portion of said conductor constituting a short-circuited quarter Wave line having an exceedingly high impedance at the operating frequency a source of high frequency energy, a source of sleet-melting energy, and a common coaxial line connecting said sources between the open ends of said elements whereby the high frequency energy is confined to the outer radiating surfaces of said elements,

.and the sleet-melting current flows in series through said elements and said high resistance conduct-or.

10. In a radio system, a doublet antenna, a translation device, a coaxial line connecting two spaced points on said doublet to said device, the terminal of the outer conductor of said line adjacent said doublet being grounded only through a section of said conductor a quarter wave-length long or an odd multiple thereof, whereby the impedance between ground and each of said points on said doublet is relatively high and said impedances are substantially balanced.

11. In a radio system, a pair of doublets each 1 comprising a pair of colinear quarter wave-length radiators, a half wave-length coaxial line connecting the input terminals of said doublets, a grounded supporting and shielding means comprising a'metallic tube having a length of onehalf wave-length and enclosing said line, each doublet being attached to and insulated from a different end of said tube, the mid-points of the conductors of the half wave-length line being connected to a transmitter and the mid-point of the outer conductor of said half wave-length line being directly connected to said tubes/hereby energized in phase and the impedance between each radiator and the ground is relatively high.

12. A system in accordance with claim 11, each radiator comprising a tubular member having a closed end, a conductor coaxially positioned within the radiators of one of the-doublets and connected to the closed ends of the radiators of said doublet, whereby each radiator of said doublet is connected to ground through a path of substantially zero impedance for frequencies other than the operating frequency and through a high impedance for the operating frequency.

13. A system in accordance with claim 11, each radiator comprising a tubular member having a closed end, a conductor coaxially positioned within the radiators of one of the doublets and connected to the closed ends of the radiators of said doublet, the mid-points of the conductors of the half wave-length line being connected to a source of sleet-melting current, vertical sleetmelting lines attached to and extending longitudinally along the metallic shielding tube, and said sleet-melting lines being connected to the sleet-melting source.

14. A turnstile antenna including in combination a supporting mast, a plurality of radiator elements, each of said elements being broadly responsive to currents covering a band of frequencies and each including an inner conductor,

a concentric conductive sleeve shorter than said inner conductor and surrounding said inner conductor, means connecting said inner conductor and said sleeve at their outer ends, said inner conductors being secured to said mast to form a plurality of horizontal arrays of four elements applying quadrature phase currents to said four elements and cophasal currents to the elements of said vertical planes.

15. A turnstile antenna including in combination a supporting mast, a plurality of radiator elements, each of said elements being broadly responsive to currents covering a band of frequencies and each including an inner conductor, a concentric conductive sleeve shorter than said inner conductor and surrounding said inner conductor, means connecting said inner conductor and said sleeve at their outer ends, said inner conductors being secured to said mast to form a plurality of horizontal arrays of four elements each, said arrays being spaced apart a half wave length, said four elements of each array being respectively located in vertical planes disposed at intervals about said mast, and four transmission lines connected to said four elements respectively to apply quadrature phase currents to said four elements and cophasal currents to the elements of said vertical planes.

16. A turnstile antenna including in combination a supporting mast, a plurality of radiator elements, each of said elements being broadly responsive to currents covering a band of frequencies and each including an inner conductor, a concentric conductive sleeve shorter than said inner conductor and surrounding said inner conductor, means connecting said inner conductor and said sleeve at their outer ends, said inner conductors being secured to said mast to form a plurality of horizontal arrays of four elements each, said arrays being spaced apart a half Wave length, said four elements of each array being respectively located in vertical planes disposed at 90 intervals about said mast, the adjacent elements in each of said vertical planes being connected by serially connected quarter wave length lines, full wave length lines connecting the junction of said quarter wave lines, and transmission lines for applying currents to said full wave length lines.

JOHN F. MORRISON.

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