US2501094A - Antenna - Google Patents

Description

2 Sheets-Sheet l R. (Z. RAYMOND ANTENNA g A mm mm March 21, 1951) Filed Dec.

. INVENTOR. RICHARD c. RAYMOND ATTORNEY March 21, 195G R. c. RAYMOND 2,5]l,94

ANTENNA Filed Pee. 10, 1945 2 Sheets-Sheet 2 III/III I III/II I0 (9 I \o m 9 u. I:

I r INVENTOR. RICHARD c. RAYMOND EAL-4L9 ATTORNEY Patented Mar. 21, 1950 STATES PATENT OFFICE ANTENNA Application December 10, 1945, Serial No. 634,099

UNITED 6 Claims.

This invention relates to radio transmitting and receiving antennas. More particularly it relates to antennas adapted to radiate or receive circularly polarized electrical energy.

2 nection with .the accompanying drawings in which:

Fig. 1 is a diagrammatic sketch showing the equivalent electrical circuit employed in antennas The attempts of the prior art to radiate or re- 5 constructed in accordance with the principles of ceive circularly polarized energy have failed for this invention; several reasons. Among the most important Fig. 2 is a cross-sectional view of an antenna reasons for this failure was the general failure structure embodying the principles of this invento radiate the energy from radiators havin a tion which radiates circularly polarized energy 1rigidly controlled and exact phase difierence in parallel to the axis of the akriitennta struczure he currents flowing in them. The more general Fig. is an end'view of -e an enna 5 rue ure failure has been made due to the inability to feed of Fig. 2 shoWing the location of the radiators; a single coaxial line with energy from a source Fig. 4 is a cross-sectional View of an antenna of single phase power and then to convert this structure embodying the principles of the presphase power to three single phase power and to ent invention which radiates circularly polarized transfer the three phase power to the radiators. energy perpendicular to the axis of the antenna It is an object of the present invention to prostructure; and vide an antenna which, when operating as a Fig. 5 is an end view of the antenna structure transmitting antenna, is fed from a single source of Fig. 4 showing the radiators. and radiates circularly polari energy parallel For simplicity of description the case of a transto its structure and, when operating as a receiving mitting antenna isdiscussed in this specification a n a, receives circularly l i d energy p but it is to be understood that the electrical and allel to its structure and delivers it through a other principles apply with equal force t single transmission line to a receiver. eiving t It is also an object of the present invention to Referring more particularly 1-, Fig 1 the provide an antenna which, when Operating as a cult employed in the antennas of this invention transmittin antenna, is fed from a single source for converting Single phase energy into three and radiates circularly polarized energy perpenphase energy and Vice Versa is generally dlcular to its structure and, when operating as a I ignated by m single phase energy is f d into receiving antenna, rece ves circularly polarized the terminals H, From terminals H H the energy perpendicular to its structure and deli energy is divided into three distinct paths or cirit through a single transmission line toa receiver. Quits denoted by '2, l3, and m which are com It Is ,anmher Qblect of the P n mventlon nected to radiators l5, l6, and I1 respectively. to pr0v 1de devlce for Converting smgte pha,se Resistor I8 is connected between circuits [2 and Into three phase energy Whose adlustabll' I3, capacitance I9 is in circuit [3, and inductance ity insures 120 degree phase difference of the 201s in circuit I 4 three phase currents.

It is a further object of the present invention It Is ob-vlous from the fimdamental fuinctlons of the resistance I8, capacitance l9, and inductto provide a transmission line for feeding energy 20 th t th t 1 between receiving or transmitting apparatus and 40 ance a e curren re a t cnfcu} antennas which are associated in the radiation m are i the Current m P m of circularly polarized energy and in which there phase with m h Current m clrcult is a variable relative phase difference of the three ieads the f 'f 12 by a phase currents he current in circuit [4 lags the current in cir- Generally this invention comprises a coaxial 5 Cult W 120 degrees ttire: airs;tttzaarrirait cti 1 havin a constant .im edance ever n fisher? along is length. Two COidllCtOlSOf a i axial linegltis fedfrom a s z pha'se d io of justable impedance are attached to the inner energywere Section is J0me 0 conductor of the tapered section of the coaxial axial line 3| at 33 and t0 the antenna pp line at its larger end and feed energy to two of Structure 30 at The taper of section 32 the radiators. The outer conductor of the coaxial and relative diamgters 0f the g t d ollllfi line is connected to a third radiator. The cur- Conduc in that Sec 10 e c be its 0 arrents in each of these radiators is 120 degrees acteristic mpeda ce re a ns unchan ed out of phase t t current in ith of th throughout its entire length. Inner conductor others. 3'6 of tapered secticin 32 is joined to conductors .31

Other objectsfeatures, and advantages of this and 38 con e ed 0 radiators 39 d specinvention will suggest themselves to those skilled tively. Outer conductor .34 of this tap d secin the art and will become apparent from the foltion is connected to outer wall 4| of housing 30 lowing description of the invention taken in conwhich acts as a continuation of the outer conductor beyond tapered section 32 and is connected to radiator 42.

Conductors 3i and 38 are secured to conductor 36 by any suitable means such as screw joints 43 and 44. At their other ends conductors 31 and 38 are provided with internally threaded portions 45 and 46 respectively into which screws 41 and 48 fit. Plungers 49 and 50 are attached to screws 41 and 48 respectively and are held in place against any lateral displacement by fingers BI and 52 or by any other suitable means.

Plungers l9 and 50 fit respectively into longitudinal openings 53 and 54 in conductors 3! and 38. They extend into these openings substantially one quarter wavelength corresponding to the central frequency of the operating range.

Plunger ll} is in contact with the inner circumference of section 53 thereby producing a shorted one quarter wavelength section which, as is well known, possesses inductive characteristics. This is the inductance 29 of the equivalent circuit shown in Fig. l. Plunger 50 is not in contact with the inner circumference of section 54, therefore it follows that section 54 is an open circuited one quarter wavelength line and possesses capacitive characteristics. This is the capacitance it! of the equivalent circuit shown in Fig. l.

Screws 4'! and 48 may be manually positioned in threaded sections 45 and 46 to move plungers 49 and 50 thereby adjusting the effective electrical length of sections 53 and 54. To change the optimum operating frequency these plungers are moved so that sections 53 and t remain one quarter wavelength, as shown, so that the currents in conductors 31 and 38 are 120 degrees out of phase with each other, Changes in the relative positions of plungers 49 and 59 will change this phase relationship. Conductors 3! and 38 are permanently secured within housing in the position shown by the cylindrical dielectric supports 55 and 56.

A folded section 5'! is attached outside of housing 30 to outer conductor 4 I In this embodiment it is electrically connected at its end remote from the radiators and, therefore, acts as a choke to prevent conductor 4i itself from acting as a radiator.

The radiators 39, 10, and 42 are physically positioned 120 degrees apart at the end of housing 30 and perpendicular to its longitudinal axis and radiate energy in a forward direction parallel to the axis of the housing 30.

When it is desired to radiate energy in a direction perpendicular to the axis of housing 30, the same structure may be used with the modification of a few details which may be understood by referring to Figs. 4 and 5. Coaxial line 3|, tapered section 32, and conductors 37 and 38 and their associated parts such as plungers 49 and 50 are similar to the corresponding parts in the embodiment just described. In this embodiment, however, outer conductor 6i of housing 30, instead of being connected directly to one of the radiators as in the previously described embodiment, is terminated along a plane perpendicular to the longitudinal axes of conductors 3i and 38 a distance away from radiators 62 and 63 which are connected solely to conductors 3'! and 38 respectively. These radiators instead of being perpendicular to the longitudinal axis of their respective conductor make an angle of 30 degrees with it. A cylindrical element 64 is, in this embodiment, electrically connected to the radiator end of conductor 6! and folded back parallel to that conductor so that it serves asthe third radiator. The radiated energy from radiators 62, 63 and 64 combine to produce circularly polarized radiation which is perpendicular to the axis of housing 3|].

It is seen from the above description of the present invention that the antennas described have wide application and usefulness and that considerable utility may be added to apparatus by associating with it either or both embodiments described.

While there has been here described what is at present considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention.

What is claimed is:

1. In an antenna system for propagating perpendicular to said antenna structure circularly polarized waves, a coaxial transmission line, three radiating elements, the first of said radiating elements being a folded one-quarter wavelength section of the outer conductor of said transmission line, the second of said radiating elements being connected to the inner conductor of said transmission line through a capacitance, and the third of said radiating elements being connected to the inner conductor of said transmission line through an inductance, and means for adjusting said capacitance and inductance whereby the phase relationship between the currents in said radiating elements may be adjusted.

2. In an antenna system for propagating perpendicular to said antenna structure circularly polarized waves, a coaxial transmission line, three radiating elements, the first of said radiating elements being a folded one-quarter wavelength section of the outer conductor of said transmission line, the second of said radiating elements being connected to the inner conductor of said transmission line through a capacitance, and the third of said radiating elements being connected to the inner conductor of said transmission line through an inductance, and means for adjusting said capacitance and inductance whereby the optimum frequency of said system may be altered.

3. In an antenna system for propagating perpendicular to said antenna structure circularly polarized waves, a coaxial transmission line, three radiating elements, the first of said radiating elements being a folded one-quarter wavelength section of the outer conductor of said transmission line, the second of said radiating elements being connected to the inner conductor of said transmission line through a capacitance, and the third of said radiating elements being connected to the inner conductor of said transmission line through an inductance, the values of said inductance and said capacitance being such that the currents in said radiating elements are separated from each other by degrees.

4. An antenna for radiating circularly .polarized waves comprising a tapered coaxial transmission line, means for connecting the smaller end of said transmission line to a source of electromagnetic energy, first, second and third energy radiating elements having coplanar axes, a conductive sleeve for connecting said first radiating element to the larger end of the outer conductor of said coaxial line, first and second parallel conductors disposed within said sleeve for connecting said second and third radiating elements to diametrically opposite points on the larger end of the inner conductor of said coaxial line, said first and second conductors-comprising variable impedance means for varying the phase of energy supplied to said second and third radiating elements.

5. An antenna for radiating circularly polarized waves comprising a tapered coaxial transmission line, means for connecting the smaller end of said transmission line to a source of electromagnetic energy, first, second and third radiating elements having coplanar axes, said elements being so arranged that the axes of said three elements meet at a common point, a conductive sleeve for connecting said first radiating element to the larger end of the outer conductor of said coaxial line, first and second parallel conductors disposed within said sleev and parallel to the axis thereof for connecting said second and third radiating elements to diametrically opposite points on the larger end of the inner conductor of said coaxial line, said first and second conductors each comprising first and second conductive elements, variable capacitive means j0ining said first and second conductive elements of said first conductor, and variable inductive means joining said first and second conductive elements of said first conductor.

6. An antenna for radiating circularly polarized waves comprising a tapered coaxial transmission line, means for connecting the smaller end of said transmission line to a source of electromagnetic energy, first, second, and third radiating elements having coplanar axes arranged so that the axes of said three elements meet at a common point at angles of substantially 120 degrees, a conductive sleeve for connecting said first radiating element to the larger end of the outer conductor of said coaxial line, first and second parallel conductors disposed within said sleeve and parallel to the axis thereof for connecting said second and third radiating elements to diametrically opposite points on the larger end of the inner conductor of said coaxial line, said first and second conductors each comprising first and second colinear conductive elements, variable capacitive means joining said first and second conductive elements of said first conductor, said capacitive means being disposed in a coaxial relationship to said first and second conductive elements, and variable inductive means joining said first and second conductive elements of said second conductor, said inductive means being disposed in a coaxial relationship to said first and second conductive elements.

RICHARD C. RAYMOND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,014,732 Hansell Sept. 17, 1935 2,239,724 Lindenblad Apr. 29, 1941 2,245,693 Lindenblad June 17, 1941 2,286,179 Lindenblad June 9, 1942 2,297,516 Walter Sept. 29, 1942 2,368,286 Carlson Jan. 30, 1945 2,420,967 Moore May 20, 1947

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