US2118396A - Construction of aerial systems for use on short waves - Google Patents

Description

May 24, 1938. N. E.. DAVIS ET AI.

CONSTRUCTION OF AERIAL SYSTEMS FOR USE ON SHORT WAVES Filed Jan. l0, 1935 2 Sheets-Sheet l INVENTOR. NORMAN E. DAVIS FREDERICK J. AINSLEY ATTORNEY.

May 24, 1938. N. E. DAVIS Er AL 2,118,396

CONSTRUCTION OF AERIAL SYSTEMS FOR USE ON SHORT WAVES Filed Jan. 10, 1955 2 Sheets-Sheet 2 INVENTOR. NORMAN E. DAws FREDERlcK J.A|NsLEY BY r/@ 7 /ww-(VL/ ATTORNEY,

Patented May 24, 1938 UNITED STATES PATENT OFFICE CONSTRUCTION OF AERIAL SYSTEMS FOR USE ON SHORT WAVES Application January 10, 1935, Serial No. 1,190 In Great Britain January 20, 1934 4 Claims.

This invention relates to constructions of aerial systems for use on short waves or so-called ultra short waves. More specifically, the invention relates to constructions for extending aerial systems wherein the aerial is extended not in a single straight line, but in effect, in a plurality of more or less parallel straight lines, portions of the aerial system lying in said plurality of lines being joined in series by transverse connections between them.

It is very important that such aerials, more especially when they are for use on wave lengths of only a few meters or less, should be of rigid construction in order that variations in the distances between different parts of the aerial and between the aerial and adjacent objects-with consequent variations in aerial properties and characteristics-shall be reduced as far as possible. It is also often required that the aerial construction shall be self-supporting, i. e., shall not require supporting guys. As will be seen later, the present invention enables these requirements to be readily satisfied.

Aerials which may be regarded as extended in a plurality of lines in the sense in which this phrase is used herein, are described in United States Patent No. 1,957,949, dated May 8, 1934, which patent describes directive aerials of the type set forth in British Patents Nos. 242,342 and 285,106 and wherein the intermediate, folded portions of the wire or conductor are so arranged that they radiate effectively in the same direction as the straight portions. For example, Fig. 2 of United States Patent No. 1,957,949, illustrates an aerial system in which a straight half-wave length A is followed by a reversed or folded half Wave length B and then by a straight half-wave length C, a reversed half wave length D, a further straight half wave length E in the same straight line as portion A, a further reversed half wave length F, a straight half wave length G in line with length C, and so on, the phase relation of the currents in successive half wave lengths being such that the reversed sections B, D, F add to the ellective field strength due to the straight wire sections A, C, E. Thus, from the point of view of this application, an aerial as illustrated in Fig. 2 of United States Patent No. 1,957,949 may be regarded as an aerial system which is extended in (Cl. Z50- 33) lengths of the aerial are, of course, in series with one another, the series connection being made by short transverse portions of conductor which are at right angles to the three lines of extension. Figs. 3, 4 and 5 of the above mentioned United States Patent No. 1,957,949 illustrate aerials of a type similar to that of Fig. 2, and the present invention is also applicable to these aerials.

The object of the present invention is to provide a simple, rigid, easily erected and relatively portable construction for an aerial of the kind which is extended in a plurality of parallel or approximately parallel lines.

According to this invention, a construction for an aerial of the kind referred to comprises a plurality of approximately parallel adjacent masts (for example in the form of rods or tubes) each mast lying in one of the plurality cf lines of extension of the aerial, and portions only of each mast being utilized as the aerial proper, said portions being connected together as required by transverse connectors extending between the masts.

Where anv aerial construction, according to this invention, is required to be of any very great height, it will generally be necessary to provide cross braces and diagonal struts or tension members between the masts, these braces and struts or tension members being additional to any bracing effect provided by the inter-connections between the masts.

According to an important sub-ordinate feature of this invention, the cross braces are 1ocated at, and diagonal struts or tension members are arranged between, points in the masts where the alternating voltage on the aerial portions proper is zero.

In preferred embodiments of the invention, three masts arranged at the corners of an equilateral triangle are employed and cross bracing is provided by means of bracing tubes or plates having a triangular arrangement of holes through which the masts pass, the masts being built up of sections insulated fiom one another where required.

The invention is illustrated in the accompanying drawings in which:

Fig. 1 shows one form of construction in accordance with the invention;

Fig. 2 is a diagrammatic view showing in full lines the portions which constitute the aerial proper; and

Figs. 3-6, inclusive, show details oi construction.

Referring to the drawings, an aerial system comprises three vertical or approximately vertical masts l, 2, 3, arranged close together and at the corners of an imaginary equilateral triangle. Each mast stands upon a foot insulator 4, 5 or 6 mounted on a suitable carrier or bed plate 'l and the masts are braced together at suitable intervals in the height of the aerial structure. The three masts are sectionalized and the sections insulated from one another in a manner to be described later. As above stated, those portions of the masts which are to constitute the aerial proper are connected in Series with one another. The aerial proper comprises a rst, vertical portion A included in the mast I and extending upwards from the bottom thereof; a second, horizontal portion B connecting the top of the portion A to the top of a portion C of mast 2 which is spaced some distance from the bottom thereof; a third, vertical portion C included in mast 2; a fourth, horizontal portion D connecting the bottom of the portion C to the bottom of a fth, vertical portion E in mast 3; a sixth, horizontal portion F connecting the top of the fifth portion E to the top of a seventh, vertical portion G in mast 2; an eighth, hori- Zontal portion H connecting the bottom of the seventh portion G to the bottom of a ninth, vertical portion J in mast l and in the same straight line as portion A; and so on until the required height has been obtained. Insulators are included at 8 and 9 in mast l to insulate the portions A and J from one another; insulators are included at l0, Il, l2 and I3 in mast 2 to insulate the portions C and G from one another and also to insulate these portions from the mast portions respectively below and above them; and insulators are included at l5 and I6 in mast 3 to insulate the portion E at both ends; in short, insulators are interposed in the masts as necessary properly to insulate the portions thereof which are included in the aerial proper. It will be appreciated that the aerial proper (Fig. 2) is thus so constructed as to consist of a straight half wave length, followed by a reversed or folded hali wave length, followed by a straight half wave length, followed by a reversed half wave length, followed b-y a straight half wave length and so on. Insulated triangularly arranged braces l1, I8 are arranged as shown and are, like the insulators, at points of zero alternating potential so far as the aerial proper is concerned, and thus losses due to circulating currents in these braces are minimized or eliminated. The whole construction may be additionally strengthened by diagonal struts or tension members which are diagonal with regard to the races of the imaginary triangular prism sections into which the whole structure may be regarded as divided. Thus there may be a diagonal member between the bottom of mast i and that end of portion B which is in mast 2, another diagonal member between the top end of the said rst diagonal member and the bottom of portion J, and so on, there being one diagonal strut or tension member in each face of the triangular prism sections whether long or short. Guys may, ii desired, be attached to the apices of one or more of the triangular braces to assist in giving support.

It will be appreciated that aerial structures, in accordance with this invention, can readily be made portable and are relatively easy to erect in high situations, such as on the ridges of buildings.

Figs. 3 and 4 show the details of construction at triangular brace points, such as the location of the brace Il. The brace includes three straight tubes il', each of which is split at both ends as shown at 20. On each mast (e. g. mast 2) is an externally screw-threaded sleeve 24 held in place by pins 22 and 23, and over this sleeve is iitted an insulator i 9 formed like a tube with two slightly tapered radial arms. The insulator is located by nuts 25 on the sleeve 24. The split ends of the tubes Il are threaded and are pushed over the insulator arms, and the arrangement is such that when the nuts 2l are screwed along the tubes Il' towards the mast, the slits 20 are closed down somewhat to allow the tubes to taper down so as to t upon and grip the tapered insulator arms. When the bores in the ends of tubes Il are being machined, the slits should be opened slightly so that when they are closed by the nuts the tube taper will t the insulator taper. Fig. 5 shows partly in section the detail at points, such as the ends of the portions between portions A and J, and it will be thought that these ilgureS will be obvious without further description beyond that 26 and 21 are insulators. As will be apparent, the split tubular method of gripping tapered insulators is also employed in Fig. 5. Fig. 6 shows the details at points such as X (Fig. 1) 28 being an insulator.

What is claimed is:

1. An aerial comprising a plurality of rigid, approximately parallel and adjacent hollow metallic masts each of which is composed of a plu- C rality of conductive sections insulated from one another, and transverse metallic tubular connectors extending between the masts and connecting certain of the conductive sections together in series, the sections and transverse contending between the masts and connecting certain l of the conductive sections together in series, the sections and transverse connectors being so arranged that said connectors together with the mast sections interconnected thereby constitute an aerial proper which is insulated from the rest l of the mast structure, and hollow metallic braces interlacing said masts at points of zero alternating potential and insulated therefrom.

3. An aerial in accordance with claim 2, characterized in this that said masts are arranged vertically and are supported at their lower ends.

4. An aerial comprising a plurality of rigid, approximately parallel, adjacent hollow metallic masts arranged each in one of the plurality of lines of extension of the aerial, portions only of said masts being utilized as the aerial proper, said portions being connected together in series by transverse metallic connectors extending between the masts, insulators between said portions and the immediately adjacent portions in the same straight line, said masts being erected vertically and supported at the base of the aerial.

NORMAN EUSTACE DAVIS. FREDERICK JAMES AINSLE'Y.

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