US2407250A - Directive antenna - Google Patents

Description

Set. W, 1946.

H. G. BUSIGNIES 7,250?

DIRECTIVE ANTENNA Filed Oct. 30, 1941 2 Sheets-Sheet l iHiHilli 15 zmwswvraa ELE SOURCE DIRECTIVE ANTENNA Filed Oct. 30, 19 41 2 Sheets-Sheet 2 Patented Sept. 10, 1946 ZAQZZSG DIRECTIVE ANTENNA Henri G. Busignies, Forest Hills, N. 1., assignor to Federal Telephone and Radio Corporation, a

corporation of Delaware Application ()ctober 30, 1941, Serial No. 417,152

(Cl. 250-1l) 10 Claims.

This invention relates to directive antenna systems, and in particular to improvements in variably directive devices for transmitting and/or receiving purposes.

It is an object of the invention to provide improved means for varying the directivity of an antenna.

More specifically, and with regard to directive antennas, it is an object to provide improved means for periodically rendering an antenna rotatingly directive throughout a generally conical orbit about the axis of said orbit.

Still more specifically, it is an object to provide means for periodically rotating the directional axis of a directive antenna at a constant angle with the axis of rotation, whereby the locus of said directional axis is a generally conical orbit about the axis of rotation.

Another object is to provide an improved reflector of radiant energy.

It is also an object to provide an improved absorbent of radiant energy.

A further object is to provide improved means for varying impedance offered to radiant energy radiated or being detected by an antenna whereby directional transmission or reception may be obtained.

A more specific object is to provide means for utilizing a moving ionized field in conjunction with an antenna for obtaining directional transmission or reception.

A still more specific object is to provide means for setting up an ionized field shifting eccentrically about an axis.

Other objects and various further features of novelty and invention will hereinafter be pointed out or will become apparent to those skilled in the art from a reading of the following specification in conjunction with the drawings included herewith. In said drawings,

Fig. 1 is a schematic showing of a device for producing an eccentrically shifting ionized field in accordance with features of the invention;

Figs. 2 and 3 illustrate schematically how a device according to Fig. 1 may be employed in cooperation with an antenna to producenovel directive effects in accordance with the invention;

Fig. 4 illustrates schematically an alternative embodiment of the device shown in Fig. 1;

Fig. 5 illustrates schematically a, further alternative embodiment illustrative of the invention; and

Figs. 6 and. 7 are plan view showings of certain elements in the apparatus of Fig. 5.

In connection with certain types of radio direction finders, it has been proposed to transmit radiant energy periodically in a plurality of different directive senses and to employ received. reflections of such energy to determine distance, direction, or other characteristics of a reflecting body. Alternately, and for similar purposes, some of these systems propose transmitting radiant energy in a constant generally directional sense while rendering a receiving antenna periodicaily responsive to received reflections of such energy as reflected from variously located bodies. Such systems have been disclosed, for example, in my copending application entitled Aircraft Indentifier, filed on even date herewith.

The above mentioned application related particularly to radio apparatus for detecting the location of aircraft or other reflecting bodies and proposed the use of an antenna system which was recurringly directive throughout a generally conical orbit. A mechanical set up was disclosed for producing the desired directivity pattern, and it was also mentioned therein that either a wholly electrical system or a rotating ionized field in accordance with the present invention could be employed.

Broadly speaking, the present invention proposes to use the properties of an ionized field either to absorb or to refiect radiant energy in order to obtain novel directive effects. A chamber filled with an ionizable medium and appropriately provided with electrodes for ionizing the same is suitably disposed with respect to an antenna whereby the ionized field present therein ma either reflect or absorb energy being radiated from or receivd by the antenna. Preferably, the electrodes within the chamber are so disposed and energized that a shifting ionized field is set up therein, which field shifts eccentrically of an axis of the antenna with substantially uniform density throughout its cycle of shifting operation.

Fig. 1 shows schematically a device for setting up such an eccentrically shifting, preferably eccentrically rotating, ionized field. The device comprises a chamber 5 preferably of generally circular cross section and having a plurality of electrodes 6, i, 8. 3, H therein. Chamber 5 may be filled with an ionizable gaseous medium, such as neon, for example, In the form shown, chamber 5 is provided with two pairs of diametrically opposed electrodes, all spaced equally from a generally central electrode member iii. In accordance with the embodiment shown in Fig. l, at any instant the ionized field preferably extends over substantially a quadrant sector of the cross section shown, and is thus set up between the electrode I9 and either one or two adjacent of the outer electrodes.

A suitable circuit for energizing the electrode system so as to set up the desired eccentrically rotating field also shown in Fig. 1. In the form shown, two preferably equal voltages spaced 90 wi in respect to each other, may be generated by the two phase alternator H and supplied to potentiometers i2 and 53 respectively. The midpoints of potentiometers l2 and it are connected to the central electrode H), as is indicated. by the ground connection. Each end of potentiometer I2 is connected to electrodes of one pair of op posed electrodes 9 through rectifier means It, i5 respectively, and each end of potentiometer I3 is connected to electrodes 5 and 8 of the other pair of opposed electrodes through rectifier means it, ll.

With the circuit 50 described. an ionizing potential ma first be set up say. between electrodes 6 and IE1. It is clear that this potential is set up when the voltage across potentiometer I3 as generated by Winding 5 lb of the alternator is a maximum and in the direction indicated by the arrow E8. No ionizing potential will be set up between electrodes 8 and iii at this instant due to the blocking operation of rectifier Hi, as will be clear. As alternator ll continues to rotate, the voltage generated in winding Hb will decrease and a voltage will appear across potentiometer ,2 as generated by winding Ila. This voltage may be in the direction indicated by arrow l9, and due to the passing action of rectifier I4 and the blocking action of rectifier 45, will begin to set up an ionizing potential between electrodes 1 and iii. The effect of decreasing ionizing potential between electrodes ii and ill and increasing ionizing potential between electrodes 5 and I ll will be bodily to displace the sectoral ionized pattern in a clockwise sense about electrode l6 and when the voltage across potentiometer l2 reaches a maximum in the direction i9, the ionized sector will appear wholly between. electrodes l and IE as will be clear. Thus, it is possible to generate an ionized field rotating eccentrically about an axis, and the use of such an ionized field will now be described in connection with two types of antenna structures.

In Fig. 2, I show how the eccentrically rotating field may be employed .as a radiant energy absorber to produce desired directive effects. In Fig. 2, chamber 5 is shown in partly broken away elevation and disposed preferably concentrically with the axis of a directive antenna structure 20 which may be employed in conjunction with ap-- propriate transmitter or receiving means 2|. It is clear that by successively eccentrically blocking out the portions of the directive pattern generated by antenna Ell, novel directional transmitting or receiving eifects may be obtained. In the case described, if antenna 28 is a transmitting antenna, the pattern of radiated energy will be periodically displaced eccentrically of the axis of antenna throughout a generally conical orbit.

In the form shown in Fig. 3, I show how an eccentrically rotating ionized field may be employed as a reflector to produce novel directional effects in accordance withthe invention. Here again, a chamber 5, containing the ionizable me-, dium, is shown in partly broken awa elevation but is preferably shaped generally parabolically for better reflecting and focussing purposes. In connection with such a reflector, a dipole 22 may be employed as the radiator or receiver of radiant energy and is preferably disposed along the axis of chamber 5' and generally at the focal point thereof. In the sense of Fig. 3, antenna 22 will have a normal radiation generally to the left and to the right symmetrically about the axis thereof. Energy radiated generally to the right of antenna 22 will however. strike the eccentrically rotating ionized field produced in chamber '5. It is clear that the efiect of such a field will be to reflect a portion of such energy generally to the left, thus reinforcing radiation to the left and providing an overall maximum radiation periodically rotating eccentrically about the axis of antenna 22.

In an alternate preferred form of the invention, I provide means for extending the sector comprising the ionized field to cover an are greater than that possible with the apparatus disclosed in connection with Fig. 1. Fig. 4 shows a circuit for generating such a field in. which the ionized area extends over substantially three quadrants of thearea comprehended within the outer electrodes. The chamber 5 and electrodes 6, l, 8, 9, it ma be the same in structure as in the case of Fig. l. As also in the case of Fig. 1, alternator H may supply substantially equal voltages in quadrature relation to potentiometers l2 and I3 respectively. The midpoints of these potentiometers and central electrode H) are again grounded. However, each of the lines connecting terminals of potentiometers l2 and I 3 to the outer electrodes is provided with rectifiers 23, 24, 25, 26 and appropriately polarized batteries 21, 23, 29, 30. Batteries 2? 39 may supply sufiicient potential for ionization purposes and rectifiers 23 26 preferably pass such potential and block an excess thereover.

The effect of such a structure will be at any instant to set up an ionized field over a sector comprising substantially the area between any three of the outer electrodes and the central electrode in approximately the following manner. Consider again the instant in which voltage generated across potentiometer I3 is a maximum in the direction It. Rectifier 23 will serve to block an application of potential between electrodes 5 and I3 and an ionized field may thus, in the absence of batteries 21, 28, 29, 39, be set up between electrodes 8 and i0. However, simultaneously, batteries 22', 28, 29, 3B are all supplying sufficient potential for ionization and such potential is opposed in sense to that set up between electrodes 6 and lil due to the voltage is. As a result the net potential applied between electrodes 6 and It at the instant under consideration is in the neighborhood of zero (or at least should preferably be less than an ionizing potential) so that at any instant a quadrant or other small sector may be non-ionized.

It will now be clear, recalling the discussion of operation of the circuit of Fig. 1 that, as the maximum voltage supplied by alternator H rotates in phase, the non-ionized quadrant or other small sector just referred to may rotate accordingly. It is thus possible to set up an eccentrically rotating ionized field which at any instant maycomprise substantially more than half the area within the outer electrodes.

In the embodiments of the invention thus far described it may be that the central electrode member 10 will have undesirable reflecting, distorting or'other effects upon radiated or received energy. In that event I propose an alternative embodiment illustrated in one form in Fig. 5. This alternative apparatus eliminates any need for a central electrode and provides the possibility of extending the ionized field sector to include a wide range of arcs from, say a quadrant up to three quadrants.

A in the case of the previously discussed structures, the embodiment according to Fig. 5 comprises within an envelope 40 an ionizable medium and a plurality of electrode structures AA', B-B' H-H. These electrode structures are preferably equally spaced generally along the circumference of an imaginary circle. In accordance with features of the invention and for purposes which will later become apparent, each such electrode structure comprises a plurality of closely-spaced electrodes, possible preferred forms of which have been illustrated in Fig. 6 and 7. The form shown in Fig. 6 depicts electrode structure A--A a comprising two electrodes A and A, each having protruding or lobeshaped portions 4!, ll and correspondingly recessed lobe-shaped portions 42, 32'. In the form shown in Fig. '7 electrodes A and A each comprise a plurality of relatively well spaced electrode surfaces 33. it, and each of the surfaces say 43 of electrode A is disposed between surfaces 63' of electrode A. Preferably electrodes A and A are provided with a large plurality of lobes and recesses in the Fig. 6 form and with a large plurality of surfaces in the Fig. 7 form, whereby the alternate use of either electrode A or A will have little efiect in displacing an ionized field set up between electrode structure AA' and any other electrode structure, as will later be clear.

In Fig. 5 the various electrode structures AA', BB, etc. are shown with a solid-line designation, e. g. A, and a dotted line, e. g. A. Such a method of designation indicates schematically that the respective surfaces of both electrodes A and A are coplanar (perpendicular to the sense of Fig. 5) and insulatingly spaced with respect to each other, as clearly shown in Figs. 6 and 7.

In the embodiment of Fig. 5, I preferably employ means supplying a plurality of phase-displaced voltages for energizing appropriate pairs of electrodes within chamber 5'] to set up a desired rotating ionized field. In the preferred form shown this plurality of voltages corresponds with the number of electrode structures AA', B-B, etc. and may be supplied by an appropriately Wound alternator 44. Alternator 44 includes a number of output terminals a-a, 72-42 71-h, yielding a corresponding number of alternating voltages phase displaced preferably equally with respect to each other. The mode of connecting the various phase outputs of alternator M to electrode structures AA', BB, etc. shown in Fig. 5 is merely illustrative, and it is to be understood that other connection schemes may be devised to accomplish substantially the same results.

In the form shown, successive output windings of alternator a l are connected between an electrode of one electrode structure and that of another structure displaced a few structures away. Specifically, the output of winding aa' is applied between electrodes A and D, the output of winding bb between electrodes B and E, and soon.

Let us now consider the effect of successive maximum voltages in the alternator windings during operation. For illustration, assume the instant at which voltage in winding a-a' is a maximum in one direction. Voltages in windings bb' and h'-h will be somewhat less, but in the same sense; and voltages in windings c-c' and CIA 6 g'g may be rather low, but also in the same sense.

The effect of a, maximum and large voltage applied between electrodes A and D will be suflicient to produce an ionized field therebetween to cover a substantial chord of the tube All. The effect of less voltage being applied simultaneously between electrodes B and E, and C and H, respectively, may be to set up an ionized field therebetween, if the voltage thus provided be sufficient to produce ionization. As regards the relatively low voltages from windings 0-0 and gg, respectively, it is not likely that they will be sufficient to produce ionization between electrodes C and F, and B and G, respectively. The net effect of application of potentials at the instant under consideration will thus be to set up a localized ionization field extending over the sector generally defined by a starting limit at electrode structure H-H and clockwise around to electrode structure E-E, as will be clear.

Now, by considering successive instants, that is, as the output of Winding aa decreases in magnitude and as, say the output of winding b--b increases to a maximum, it will clearly be seen that the ionized field defined by the aboveidentified sector will be bodily displaced correspondingly about the axis of tube 4a.

In order to simplify showing and explanation of the circuit of Fig. 5 I have necessarily omitted a showing of additional circuit elements which it may be desirable to add. For example, some kind of output control means may be associated with alternator G l, whereby the maximum outputs of all the windings a-a, bb', etc. may be simultaneously regulated. The utility of such a regulatory system will be very apparent, for winding output may at one extreme be so adjusted as to yield ionizing potentials only when winding output is at a maximum. On the other hand, winding output may be so increased that ionizing potentials are produced in several adjacent windings at once.

The effect of such regulation will be seen to vary the angular size of ionized field produced. In the former of the above extreme conditions of output assumed, and at the instant when winding a-a' is yielding a maximum voltage, no other windings supply adequate voltage for ionization, so that the chord between electrode structures AA and D-D' will be the only ionized field. In the latter condition, even the output voltage of windings cc and gg may be suffic ently large to produce a slight degree of ionization. As a result then, at the assumed instant, the ionized field may extend almost completely around the device. It is to be noted that, inasmuch as the degree of ionization varies somewhat with potential applied, the ionized field may extend completely around tube fill, and at the same time be locally ionized to an extreme extent, due to the various ionizing potentials applied between electrodes of various electrode structures. Thus, in the latter condition assumed, ionization may be taking place between at least one electrode of all the electrode structures, but there will be a localized extremely highly ionized field extending roughly over the sector HI-I clockwise to E--E.

While I have described my invention particularly in conjunction with devices employing a plurality of electrodes and means for appropriately energizing these electrodes to obtain an eccentrically rotating or otherwise shifting ionized field, it is clear that other methods may be 7 employed. For example, it is known that an alternating voltage of high enough frequency may be sufficient to produce a steady ionized field.

It will be observed that the circumferentially disposed electrodes in all showings oi the discharge device are neither shovm as having fiat nor generally arcuate surfaces, but rather as having a slightly undulatory form. This showing has been made to call attention to the fact that some sort of design and experimental work will be necessary with respect to these surfaces in order to obtain the most uniform strength of ionized field between electrodes as that field rotates or shifts eccentrically in accordance with the invention. 1, therefore, consider that the precise form of electrode finally to be adopted is purely a matter of design.

While the foregoing description has been made in 133.1 ticular detail in connection with the preiercd forms illustrated, it is to be understood .at many modifications thereof may be made he scope and spirit of this invention. at I claim is:

A directive antenna system comprising a said element, said reflector comprising an envelope of non-conductive material, ionizable means within said envelope, electrode means for ionizitrg said ionizable means, said electrode means including electrodes disposed generally along the circumference of a circle, and means [or successively energizing said electrodes, whereby ionization within said envelope is eccentrically localized and rotated about the axis of said eccentricity.

2. A directive antenna system according to cla m 1, wherein said radiating element is generally uni-directionally directive and said reflector is disposed transverse to substantially all the radiation of said element.

3. A radiant energy directional. system including antenna means, means disposed in proximity to and positioned to reflect energy directed by said antenna means for setting up a locally ionized field, and means for periodically displacing said ionized field to variably effect the directional effect said energy.

4.. A directionally responsive receiving antenna system including a receiving element, a rehector disposed adjacent said element to reflect energy thereto, said reflector comprising an en velope non-conductive material, ionizable means wi *1 said envelope, electrode means for ionizing said ionizable means, said electrode means including electrodes disposed generally along the circumference of a circle, and means for successively energizing said electrodes, Whereby ionization within said envelope is eccentrically localized and rotated about the axis of said eccentricity.

5. A directive antenna system according to claim 1, wherein said reflector is disposed generally transverse to radiation from said element.

6. A directive antenna system according to claim 1, wherein said reflector is disposed generally transverse to radiation from said element and said chamber is of generally parabolic cross section.

7. A directionally responsive antenna system comprising an antenna for translating electromagnetic waves, a reflector for said waves disposed adjacent said antenna, said. reflector comprising an envelope of non-conductive material, ionizable means within said envelope, a plurality of opposed pairs of electrodes within said envelope for ionizing said ionizable means to produce an ionized path, and means for successively energizing electrodes in a predetermined sequence whereby the configuration of said path is varied to change the directivity of said antenna system.

8. A reflector for a directive antenna system comprising an envelope of non-conducting material, the shape oi said envelope being substantially paraboloidal, ionizing means Within said envelope for producing an ionized path, said ionizing means comprising an ionizable gaseous medium and a plurality of pairs of electrodes, said electrodes being disposed along a generally circular circumference near the periphery of said tube, means providing a plurality of phase-displaced voltages equal in number of said pairs of electrodes, and means for sequentially applying said voltages to said pairs of electrodes, whereby the configuration or said path is varied to change the directivity of said antenna system.

9. A reflector for a directive antenna system in accordance with claim 8, wherein each electrode of said opposed pairs comprises a plurality of closely spaced electrode members, each of said members having lobe-shaped portions in spaced relation to a corresponding lobe-shaped portion of another of said members.

10. A reflector for a directive antenna system in accordance with claim 8, wherein each electrode of said opposed pairs comprises two closely spaced members, each of which comprises relatively widely spaced electrode surfaces, and each of the surfaces of one of said members is disposed between the surfaces of another of said members.

HENRI G. BUSIGNIES.

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