US1816614A - Wave antenna - Google Patents

Description

July 28, 1931. R. 1-1.. RANGER WAVE ANTENNA Filed Feb. 9, 1925 2 Sheets-Sheet l CURRENT AT BACK END ANTEN NA LENGTH RH-RRNGER 3% P? July 28,1931. R. H. RANGER 1 WAVE ANTENNA Filed Feb. 9, 19123 I 2 Sheets-Sheet 2 A I l a I Patented July 28, 1931 UNITED STATES PATENT oFFIcE 'tICI-IAED HOWLAND RANGER, or BROOKLYN, NEW YORK, Assrcmon To RADIO con- POR-ATIQN or AMERICA, A CORPORATION or DELAWAR I 1 WAVE ANTENNA Application filed February 9, 1923. SerialfNo. 617,928.

This invention relates to improvements in radio receiving systems and more particularly to am improvement in the antenna described and claimed in the U. S. Patent No. 1,381,089,

June 7, 1921, to H. H. Beverage.

It is an object of this invention to provide such an antenna which will give zero back endtenna length which will be considerably less 7 than that of the wave antenna now in use.- It is a further object of this invention to provide an antenna which can be constructed relatively more cheaply than the usual form of wave antenna because of its decreased length and which will at the same time have the desirahle qualities with respect to reception which distinguish the wave antenna from other forms of antennae. A

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appendedclaims. My invention itself, however, both as to its organization and method of operation together with ways in which the particular objects thereof may be attained, will best 'be understood by reference to the following description taken in conjunction with the accompanying drawings, in which Figure 1 shows the usual form of Wave an- 'tenna according to the p'atentreferred to above, Figure-2 shows my improved form of antenna, 1

FigureB shows the variations of the characteristics of this type of antenna with the length thereof, 7

Figures 4, 5 and 6 and 7 are vector diagrams.

illustrating and explaining the principles of the wave antennae as'made' use at in my invention,

Figure 8 shows diagramatieally a wave im- ;;-*ing. .ig en a seetian (if a wn'vtmtenna,

.Figure 9 shows the directional characteristics of anide'al wave antenna one wave length long,

Figure '10 shows the directional characteristics of an antenna wave length long according to the-above cited patent,

' F lgures 11 and 12 are vector diagrams further illustrating the principles made use of in invention. Y,

grounded atone end at 3 through aresist'anee 2 and grounded at the other end at 7 throughan inductance coil 4. Associated with this inductance coil 4 in inductive relation therewith, there is provided an inductance coil 5 connected to receiving apparatus R. Transmitting stations 'A'and B are shown which are assumed to be in the planeof the antenna. The direction of the signalsfrom these staions is shown by the arrows marked I'GSPGC-Qfl tively A and B It has been found by experiment that the variations of antenna length ,givea characteristicsuchasshown in Figure 3. It, will .be noted that the current at the receiving end, 30

that is at the end remote from the transmit ting station, increases withthe length of'th'e antenna This increase will naturally not continue indefinitely since the losses in the antenna increase with the length thereof. On

the other: hand, the current at the back'end or at the end toward the transmitting stations showsan entirely different character- .isticfi It will be seen that this current increases to a maximum at wave length and decreases to a minimum for "wave length.

the antenna be exactly one wave length long. Assume that waves are being radiated from transmitting station A and that such waves are passing along the antenna. as shown by the arrow A in the direction of the antenna. Assume also that the velocity of waves along the wire having. the frequency of the transmitting station A is the same as the velocity of travel of the space Waves radiated from station A. The diflerential amount of energy picked up by the small section dm may be represented by the vector dB in Fig. 4. This energy gives rise to a differential current (ZI flowing down the wire 1 toward the receiver R.

It is apparent that the antenna may be considered as divided into an'infinite number of such differential sections and that each of these sections inturn acts to absorb a portion of energy (ZE from the space wave as it passes and that each of these portions of energy picked up may be considered as causing a current cZI to flow to the ground at 7 through coil 4. In order to obtain a clear idea as to the.

action which takes place in the receiver in response to these differential amounts of current we will return to the consideration of the differential section dw. This is assumed to be located at any point between section aim and the receiving end of the. antenna 1.

It is apparent that the energy dE which will'be picked up by section clw will be out of time phase with thelenergy (ZE picked up by the difierential element clan and it will be seen further that this dephasing will be due to the time required for the space wave to travel from the element dm to doc. Then it we represent theenergy cZE picked up by the element (Z00 by. the vector (ZE in Fig. 4, it is apparent that we may also represent the energy (ZE picked up by dw by asimilar vector 0313 where 0 is the angle representing the time required for the space wave to travel from 0390 to elm: These vectors may also be considered to represent the currents (Z1 and d1 dueto such absorbed portions of energyr However, it will be seen that the differential current (ZI travelling along the wire 1 will be dephased exactly the same amount since it was assumed that the velocity of current propagation along the wire is the same as thatof the space waves with respect to the antenna. It will thus be seen thatthe current (ZI caused by the energy dE will be in phase coincidence with the current (Z1 and as these elements else and clm are not limited in their position along the line it will be seen that as long as the assumption concerning the velocities holds true that the currents flowing in the direction of travel of-the space wave caused by the portions of energy picked up by any sections doc and da along the antenna 0? etc. represent the currents flowing at points a, b, 0, cl, 6, etc. spaced 5; wave length apart due only to the energy picked up by the r i ,It will be seen that the resultant may be represented by E as shown in Fig. 5 wherein each of the vectors a, b, 0, d etc. is rotated tional to the distance of the points a, Z), 0, from the receiving end. For instance, vector at is rotated through 860 since currents from A are dephased by that amount in flowing to the receiving end 7. In a similar manner vector 6 is rotated through an angle of 36030; 0 through an angle of 3606 0 and so on.

"As a resultof this we see that when the wave front is moving parallel to the antenna and when the velocity of the waves in space is the same as the velocity of the currents in the wire, the currents due to the energy picked up by the antenna will be in phase at all points and the current vectors will lie of the antenna and the signals still considered as coming from A. 1

We will now assume that difierential olm is taken at point a at the new receiving end 3 or back end. If we then considerdifi'erential current dIdue to the energy picked up by this section of the antenna and another increment of current (51 due to the current picked up by section dm'at point 6, wave length further on, it will be seen that there will be a lag between the'energy picked up at these two points. However, as the current d1 must flow to the receiving end 3 there will also be a 30 lag introduced by the time necessary for the current to flow to that point and as a result of this we see that these two currents will be out of phase at the end 2.

Referring now to Fig; 6, vector a represents the current at receivin end 3 due to the element of the antenna adjacent thereto,

A; of a wave length from 3, and vector 6' the current due to the section A.; of a wave length from-8, and so on.

through some angle less than 360 propor vllU It will thus be seen that the current vectors I representing the currents at the combining point no longer he along the samestralght line but are distributed symmetrically around a circle in such a manner that theycancel out and give a zero resultant. It will be seen. that for an antenna 1 wave length long the currents at the back end are represented 'by vectors forming two concentric circles; that is to say, the vectors are rotatedthrough a maximum rotation of 7 Thisgives a zero resultant and accounts for the zero reception at multlples of wavelength as shown in i Fig. 3.

It may be noted here that no account has been taken of attenuation, the efiect of which is to decrease the length of the vectors, However, the effect of attenuation willbe to transform the line connecting the ends of the vectors from a circle into a spiral which, if developed, would represent the usual hyperbolic curve of attenuation over a transmission line.

As a result ofthis it will be seen that back end reception will not be exactly zero but that there will be a small amount of unbalance due to the attenuation in the line. However, for relatively short antennae this will he the velocity of the wave in space, it will be apparentthat the velocity oi with which the space wave passes along the wire will no longer be the same as its velocity through space but will be V sec 0 N cos 0 It Will be seen that this velocity will change with the angle 0 until 0 equals where the velocity Q) will be infinite and the energy picked up by the antenna will be substantiallyzero. It is also to be noted that the energy due to each diilerentia-l section will no longer be (ZE as before but will be dE cos 6 due to the fact that the differential-sectionmay be considered as a small loop set' at an angle to the space wave. t

Fig. 9 shows the directional characteristic of this antenna in response to waves impingi on it at any angle 0. It will seen from V the proper conditions to obta n such recepthis figure that this type of antenna is quite sl'iarply directional particularly as to signals 180 directionally dephased. However, referring to Fig. 3 it will be seen that in order to take advantage of this the antenna must be at least wave length long or some whole lnultiple of wave length, There maybe circumstances which prevent erectingan antenna thislong and it is quite desirable under these circumstances as well as from a standpoint of economy to provide an antenna, for

instance 4 te of a wave length long which 55,

will present the same directional characteristies as shown in Fig. 9." However, a normal antenna wavelength hasibeen found to have a. directional characteristic such as shown by Fig. .10 and itwill be seen that the small tailsin Fig-9 havebeen given way to a comparatively large loop for back end reception. While this loopisnot as large. as the loop for front endreception, nevertheless, in. order to distinguish between front and back end reception some means mustbe provided for cutting out the back end reception by compensation which cuts down the strength ofthe front end signals.

Turning again to the vector analysis'of the problem, it may be shown by a process similar to that employed above that the currents to be combined at the back end in a A wave length antennamay be represented by vectors forming semi-circles as shown in Fig. 7 whose resultant is E This also explains incidentally why the area of the back end loop is not as large as that of the front end loop. This is due to the fact that thecurrent vectors for front "end reception lie in the same straight linewhereasthose for back end receptionlie on a-semi-c'ircle; It will be evident that we can obtain zero back end reception if by some means it is possible, so to speak, to stretch this semi-circle into a complete circle so as to provide that the resultant propagation along the line is-less than the. ,apparent velocityof the space wave along the wire whereby a greater lag is given the currents, but it will be seen that it will not v besuflicient to load the antenna haphazardly, which might give a"'distribution of vectors as shownv in Fig; ll, where the vectors are distributed through a sector; mno of a circle mm. It will be seen that there are no vectors in the sector pm and that theresultant of this distribution of vectors will be a vector E of considerable magnitude. However, if the vectors could be distributed insucha manner as to completely cover the area of the circle as shown in Fig.- 12, substantially zero back end reception would be obtained for any par ticular length of antenna and any angleof if.

incidence 6. i

will now turn. to the consideration of tion. ,It is apparent that the primary conditions to b'e obtained is a phase lag of 360 or a hole multiple thereof between ourrepresents the period of the wave, the time required for thespace Wave to pass the length lilo ' of the antenna, and for the current to flow Transposing and simplifying we obtain the ratio l )\l cos 6 Similarly, if a longer antenna is desired in order to get greater front end reception, we

- may calculate for a 720 dephasing of currents at the backend. Under these conditions must be equal to We thus arrive at the formula for zero back end reception in an antenna of any length which is I u V Z v ah-l cos where n is any integer, 1 for a 360 phase difference, 2 for 720 etc. Knowing the velocity of the waves through space and knowing the angle at which they strike the antenna it is possible to calculate the'amount of loading necessary to obtain any velocity u of the currents in the wire in order to obtain zero back end reception for any length of antenna, and for any angle 6 which the wave makes with the antenna.

' WVhile I have shown, in Figure 2, one method of obtaining this result, that is by providing loading coils 7 along the antenna,

other means of obtaining the same result, such'for instance, as lncreasing the effective antenna capacity to ground by the addition of capacity shunted between the antenna and ground, will be apparent to those skilled in the art and I do not wish to be considered as restricted to the apparatus disclosed by Fig. 2.

It will be seen that I have provided means whereby the advantages of a wave antenna may be obtained in a relatively short antenna, for instance 1 of a wave length long or shorter, thus resu ting in a considerably decreased cost of installation and upkeep without sacrificing any of the desirable directional qualities of the wave antenna.

Having described my invention, what I claim is:

1. In combination, an antenna system.

grounded at each end, and loading coils dis tributed along said antenna, said loading coils being distributed proportionally to the length of saidantenna, whereby zero back end reception is obtained for any antenna length. 1

2. The combination with an antenna grounded at each endof means for proportioning the natural constants of such antenna with respect to the length thereof to such values as to give zero back end reception for any antenna length.

3. An antenna provided with loading means distributed therealong, said loading means being so chosen and arranged as to give a ratio of velocity of currents in said antenna to the apparent velocity of space waves with respect tosaid wire, of

Z n)\-l cos 9 and less than unity wherein Z is the antenna length, n is an integer dependent upon the electrical degrees of phase difference, A is the.

wave length in space, and 6 is'the angle at which the waves impinge upon the antenna. 1 4. The method of eliminating. back end reception in an antenna grounded at both ends which consists in loading said antenna,

in a manner proportional to its length 'so that the resultant of currents flowing therein toward the back end is substantially zero at the back end.

5. The method of loading an antenna grounded at both ends which comprises the regulation of the constants of said antenna in a manner to give a velocity of currents therealong equal to vl nN-l cos 0 and the ratio of velocity and the said antenna and space currents is less than unity wherein o is the velocity of the space wave, Z is the antenna length, n is an integer dependent upon the electrical degrees of phase differ ence, is the wave length in space, andfl is the angle at which the waves impinge upon the antenna. 7

6. The method ofobtaining zero back end reception on an antenna of a length other than an even multiple of the received wave length and which is grounded at both ends which comprises loading such antenna in, proportlon to the length thereof 111a manner to provide for 360 phase displacement between the currents due to the portions of energy received at each end thereof.

r. The method of obtaining zero back end reception of antenna of "a length, mm

than an even multiple of the received wave length and which is grounded at both ends which consists in proportion to the length thereof in loading said antenna in a manner to provide a whole multiple of 360 phase displacement between the currents due to energies received at each end of said antenna.

RICHARD HOWVLAND RANGER.

CERTIFICATE OF CORRECTION.

Patent No. 1,816,614. Granted July 28, 1931, to

RICHARD HOWLAND RANGER.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, lines 3 and 4, claim 7, strike out the words "in proportion to the length thereof" and insert the same to follow the word "antenna" in line 4, same page and claim; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 3rd day of May, A. D. 1932.

M. J. Moore, (Seal) Acting Commissioner of Patents.

Images