US2369556A

US2369556A - Band antenna

Info

Publication number: US2369556A
Application number: US436535A
Authority: US
Inventors: Gamet Pierre Paul
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-03-28
Filing date: 1942-03-27
Publication date: 1945-02-13
Anticipated expiration: 1962-02-13
Also published as: GB576360A; FR961703A

Description

P. P. GAME-:T

BAND ANTENNA v Feb. 13, 1945.

Filed March 27, 1942 Patented Feb. 13, 1945 BAND ANTENNA Pierre Paul Garnet, Paris, France; vested in the Alien Property Custodian Application Marchl 27, 1942, Serial No. 436,535

A In France March 28, 1941 i Claims.

The present invention relates to improvements in multiple strand aerials, and aerials comprising a shaped nat conducting band, particularly for very high frequencies.

The invention relates more particularly to aerials or aerial systems having a high emciency and makes it necessary to modify the matchingcircuits when working `with a number of differentr wavelengths. I

On the other hand, aerials are generally'located at inaccessible places for'instance on the top of amast or of `a building and, in any case, one encounters great diiculties in changing the aerial structure or the transmission line once they are set up. However, it is most desirable to be able to use such a unit inV a 'predetermined range of wave lengths, the aerial retaining inthe said range the same properties of radiation andthe same characteristic features from the point of view ofthe transmission orreceiving apparatus withwhich it is coupled.

The present invention offers this latter advantage without making it necessary, in any way, tomodify the mechanical and electrical characteristlcs of the aerial and of the matching circuit once they are set up and mounted, the said.

aerial being designed so as to obtain` a large aperiodicity, the output radiated by this aerial remaining constant over a large range of Awave lengths, and itsoptimum operation being such that'it does not require an energizing circuit specially designed to have the best conditions of coupling and of matching of impedance.

My improved aerial permitting to attain the above mentioned objects presents the characteristic features which will appear'frorn the following description and more 'particularly from the appended claims. e.

Aerials according to the invention are shown by wayof examples in the accompanying drawing, in which:

, Figure 1 is a general perspective view of the aerial from the iront.

Figure 2 is atop plan view of the aerial.

(Cl. Z50-33) Figure 3 shows a detail of the top terminal loo Flzigllre 4 shows the developed surface -of the terminal loop on a plane.

Figure 5 is a diagram of the elementary aerial element of which the complete aerial may be considered to be composed.

The aerial is formed of a iiat conducting band I, a second iiat'conducting band 2 parallel to band I, and a flat conducting band 3 parallel to band 2 and in line with band I;' these bands vi and 3, on the one hand, and 2, on the other hand, are spaced from each other by la distance which .is small with respect to the radiated or received wave length.

The extremities 4 of band` `I,' and 5 of band 3, are bent for instance ata right angle at 6 and l, and carry

terminals

8 and 9 for securing both wires of the transmission line or the connection wires of the coupling means.

The bands I and 2, on the one hand, and 3 and 2, on the other hand, are connected together at their ends by a terminal band I0 and by a terminal band I I respectively, which are bent in the form of a loop which is such that when developed orr spread out on a plane it forms a parabolic surface. n

The electrical constants of the aerial depend upon the following dimensions: The tip-to-tip distancerat the rear of the structure shown in Fig. 1, L1 the length ofthe -branch 2, and of the lbranch Iv together wtih the branch 3, measured respectively onl the rear edges I2, and I 3-I4. e

L2 the length of the branch 2, and also of branch l together with branch '3, measured on the front edges I5, I6 and I1.

O1 the thickness distance at the rear from left to right between the edges I3 and I4, on the one hand, and I2, on the other hand, of the branches I, 3 and 2.y O2 the thickness distance-at the front from left toriglit between the edges I6 or I1, on the one hand, and I5, on the other hand, of the branches I, 3 and 2. b the depth of the aerial from front to back. f The dimensions L1, L2, O2 and b can vary over a considerable range according to the desired range of aperiodicity and the scale of frequencies to be transmitted or received. From this fact, the Vgeneral form of the aerial can be considerably modled according to the choice of the preceding dimensions.

An aerial of the described type possesses acomparatively low imepdance; it is necessary to en- ,on the other hand.. of, rectilinear form,l parallel and separated front another by a distance which is small with respect to the radiated or received wave length. These strands are connected at their extremities by terminal loops 2| and 22.

The length of each of these elementary aerialsvaries progressively within the limits L1, L2; the,` distance between each of the strands 1.9. and 2.5', on the one hand, and I8, on the other hand, varies progressively between O1 and O2. Thus, the cornplete structure is tapered in both length and breadth in a direction perpendicular to these elementary aerials, and has substantially the shape of the frustum of a cone.`

Suppose two

points

23, 24 of the wires ofthe elementary aerial at the same height X over the lower tip point 25. 'Elie-vakliteoftheL currents Il and Iai as a function of time is given to a first approximation bythe following expression-r 11:21 sin whe-re Alissa constant, T' the periodof: the. oscillations, it the, wave length and. t thev time,

These equations are true with the singie assumption that the terminal loops. do not modify the propagation of the: waves, and experience continus' this; fact.

One;` sees. that Yboth theseequations are identical in their form with the single exception of the. sign. mi theterm From the; point of view of the: eld produced at al great distancev and. since the distancev between both strands is small withrespect to the wave length, the radiation is identical: to that of a sin-gle conductor the` intensity of which `would be the sum of both preceding intensities, which sum has forli-ts expression:

I N+ 12= 2li` sin 21E-, cos an? One sees that for standingy waves this' intensity corresponds with, that of a dipole tuned to the wave length the intensity `of which at the current loop is equal to twice theY intensity in each branch, This calculation .shows welrthe radiation power of this elementary aerial and experience `confirms it' entirely.

The .aerial according to the presentA invention being, formed ofv an infinite number of these elementary aerials,l i'tl has a radiation'value which can be considered for a given frequency as the sum of the partial radiations of `each elementary aerial while taking into account their mutual inductance.

Experience shows that the radiation resistance of' this unit is nearly' constant overa large range of wave lengthsand that, on the otherhand, its aperiodicityis obtained within wide limits even then when the energizing circuit does not A correspend to the best conditions of coup-ling and ofm'atchingof the impedance.

The invention is generally applicable andcan be applied to all the aerials comprising systems of any antennae (radiogoniometers, radiobeacons); it is more particularly advantageous for transmitters working various different stations for transmitting aerials or receiving aerials `with wide band pass characteristics, in order to obtain the minimum distortion during transmission or reception, as of the image in television.

Ifclaim: 1

l. A broad band antenna particularly for ultra high frequencies, comprising a conducting band having substantially the shape of the frustum of a cone, said band being discontinuous at a region of its conical surface for the application of operati-ng, terminals to its portions adjoining said region. y

2; A broad band antenna particularly for ultrahigh frequencies, comprising .a conducting band having substantially the shape of the frustum of a cone, said band being discontinuous at a region of its conical surface for the lapplication ofv operatingA terminals to its portions adjoining said region, the smallest dimension of the base' of said cone being small with'rel'ation to the operating wave length.

31. Abroad band antenna particularly for ultra high frequencies, comprising a conducting bandl having substanti'ally'the shape of the frustum of acone whose base is a figureV composed of two parallel lines of substantially equal length joined together at their respectiveends by continuous length.

4. A broad band antenna particularly for ultra-high frequencies, comprising a conducting band' having substantially the shape of the frustumof a cone whose base is a figure composed" of two parallel lines of substantially equal length' joined togethery at their respective ends by continuous curved' lines, the distance'betwee'n said paralleldnes being small with relation to their' length and smallwith relation to the operating wave length, saidy band being discontinuous at' a region thereof for the application of operatingterminals to itsI portions adjoining saidf'region.

5'. A broad band antenna particularly for ultra highfrequencies, comprisinga conducting band having substantially the shape of the frustum of a cone whose base is a figure composed of two parallel lines of substantially equal length joined together at their respective ends by continuous curved lines, the distance. between saidparallel lines being small with relation to their length and small with relation to the operating wave length, said band being discontinuous at a region intermediate and substantially midway of a longside thereof for the application of operating ter# minals to its portions adjoining said region.

6. A broad band antenna particularly'for ultrahigh frequencies, comprising a conducting band shaped to form a substantially continuous'clos'ed surface having a longitudinal' plane of'symmet'ry Vand having a cross-section defining a plane perpendicular to said plane of symmetry and constituted of two long parallel lines of equal length connected together at their ends by continuo-us curves, said surface being tapered in both length and breadth perpendicular to the plane of said cross'section, thedistan'ce between' said parallel lines being small with relation to 'their length and small with relation to the operating lwave length '7. A broad band antennaA particularly' for ullt'rahigh frequencies,` comprising a conducting band constitutedy of the surface generated by translating parallel to itself a closed plane figure which is long relative to its breadth, and the dimensions of said gure being lat the same time continuously varied progressively in the same sense of magnitude in its successive positions as it is so translated, the distance between the long branches of said gure being small with relation to the operating wave length.

8. A broad band antenna particularly for ultrahigh frequencies, comprising a conducting band constituted of vthe surface generated by translating parallel to itself a plane gure consisting of two long parallel lines whose ends are connected together by curves, and the dimensions of said gure being at the same time continuously varied progressively in the same sense of magnitude in its successive positions as it is so translated, the distance between said parallel lines being small with relation to the operating wave length.

9. An antenna according to claim 8, the terminal curved surfaces connectingY the long sides of said surface whose elements are parallel, being surfaces which are -parabolic surfaces when de veloped on a plane.

10. An antenna according to claim 8, one of the long sides of said surface being discontinuous at a region thereof intermediate its length for the application of operating terminals thereto to its portions adjoining said region.

PIERRE PAUL GAMET.