US3550046A - Flush contact step attenuator for coaxial circuits - Google Patents

Description

9 1970 H. BACHER 3556,@

FLUSH CONTACT STEP ATTENUATOR FOR COAXIAL CIRCUITS Filed March 29, 1968 3 Sheets-Sheet 1 INVENTOR Helmuf Bacher BY W ATTORNEY Dec. 22, 1970 H. BACHER FLUSH CONTACT STEP ATTENUATOR FOR COAXIAL CIRCUITS Filed March 29, 1968 3 Sheets-Sheet 2 INVENTOR Helmut Bacher ATTORNEY Dec. 22, 1970 H. BACHER 3,550,046

FLUSH CONTACT STEP ATTENUATOR FOR COAXIAL CIHCUITS Filed March 29, 1968 3 Sheets-Sheet 3 FIG. 6.

INVENTOR He /muf Bacher M Kz M ATTORNEY United States Patent Office 3,550,046 Patented Dec. 22, 1970 3,550,046 FLUSH CONTACT STEP ATTENUATOR FOR COAXIAL CIRCUITS Helmut Bacher, Arlington, Va., assignor to Weinsclel Engineering Co., Gaitlersburg, Md., a corporation of Delaware Filed Mar. 29, 1968, Ser. No. 717,285 Int. Cl. H01p 1/22 U.S. Cl. 333-81 4 Claims ABSTRACT OF THE DISCLOSURE A cylinder drum step attenuator for coaxial cable microwave circuits, stepped by a full rotation cycle of the drive shaft in such fashion that during half of a rotaton cycle of the drive shaft the drum is held rigidly in position with one attenuator in the circut, and during the next half turn of the shaft, the drum is smoothly rotated an amount sufficient to put the next attenuator into the circuit.

This invention relates to step attenuators for microwave circuits, of the general type disclosed ir U.S. patent application Ser. No. 558,927, filed June 20, 1966, for Flush Contact Step Attenuator, by Bacher et al. The invention 'elates to an improved drive for this type of attenuator, the drive comprising a modified Geneva gear drive for stepping a cylindrical drum-type attenuator so as to successively insert attenuator elements mounted thereon into a coaxial circuit. Successive attenuators are stepped by successive full turns of the drive step, the mechanism being such that during half the turn the drum is rigidly held against rotation, so that a selected attenuator is properly positioned in the coaxial circut for connection thereto, and during the next half turn of the drive shaft, the drum is moved sufficiently to insert the next attenuator into the circut, the motion being accomplished smoothly and gradually, being essentially a simple harmonic motion, which permits the drive shaft to be motor driven, so that any desired attenuator can be put into the circut with extreme rapidity, even though this may require stepping the attenuator drum through practically a complete cycle. The drum mechanism is simple and rugged, and easily machined by standard Operations, yet can readily be made to position a selected attenuator with great precision to hold it rigidly against any possibility of displacement.

The specific nature of the invention, as well as other objects and advantages thereof, will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings, in which:

FIG. 1 is a plan View of an attenuator according to the invention;

FIG. 2 is an end view of the drum or cylinder mounting a set of stepped attenuators of dierent values for selective nsertion into the circut;

FIGS. 3A-3F are schematic drawings showings the relative position of the drive shaft and driven drum element during a complete rotation cycle of the drive shaft;

FIG. 4 is a schematic View showing a motor-driven attenuator;

FIG. S is a sectonal View taken on line 5 -5 of FIG. 6; and

FIG. 6 is a top view of a modified form of the invention.

Referring to FIG. 1, the attenuator is mounted in a suitable box or yolk 2 and comprises a cylindrical drum 3 rotatable on a shaft 4 which is supported in suitable bearngs in the yolk 2. The drum 3 is provided with a number of apertures 6 for holding attenuators, which are preferably of the same type as disclosed in the copendng application Ser. No. 558927 above referred to. The attenuators 7 extend beyond the drum and are provided with Contacts 8 and 9 adapted to engage stationary coaxial contacts 11 and 12 respectively, which are preferably of the same flush type as disclosed in the above-mentioned application. Conventional coaxial transmission line connectors 10 and -10a are provided for connection to an external circuit. Thus, by rotating the drum 3 on its axis, successive attenuators can be engaged with the contacts 11 and 12, and thus put into the microwave circut associated with these terminals. In the prior application, a starwheel drive and detent arrangement was employed to rotate the cylinder 3 and thus to step the attenuator. In the present disclosure, a modified Geneva-gear arrangement is used to step the attenuator, comprising a drive shaft 13, which may be manually driven by knob 14 as disclosed in FIG. 1, or may be motor driven as disclosed by FIG. 4. Fixed to the end of shaft 13 is a disc 16, on the forward surface of which is fixed a ball 17 radially displaced from the axis shaft 13 by substantially one-half of the distance which the circumference of drum 3 must move in order to step from one attenuator to the next. Also fixed to disc 16 is a smaller radial distance from the center of the shaft than ball 17 is a stop boss 18 having an outer surface which is semi-cylindrical in form. The inner surface of boss 18 is cut away as shown at 19 to insure adequate clearance during operation, as will be explaned below, although in some cases the element 18 could be one-half of a rigid cylindrical rod if desired.

One the surface of drum 3 there is an annular raised band 19 containing a series of grooves or Channels 21 spaced apart a distance correspondng to the desired stepping distance, and between the channels 21 there are a series of circular cut out portions 22 having a generally cylindrical configuration and dimensioned to snugly receive the outer cylindrical surface of stop boss 18.

As best seen in FIG. 1, assuming the kno'b 14 is turned so as to move the ball 17 to the left, the ball will enter slot 21 at the top of the figure, and as rotation continues for a half turn, the cylinder will be rotated through one step, the relationshp being as shown in FIGS. 3B, 3C, 3D and 3F, so that the drum is rotated for a sufiicient distance to engage the next successive attenuator with terminals 11 and 12. It will be noted that just as the ball 17 is leaving the slot, and the position shown in FIG. 3F, the stop boss 18 has engaged the cut-out 22 sufficiently so that the drum is now immovable in either direction, and this engagement of these two elements continues during the next half-turn of the shaft 13 until the position shown in FIG. 3B is reached, when the stepping action is again initiated during the next half-turn of the shaft. It is thus apparent that the shaft does not need to be positioned very accurately in order for the attenuator to be accurately aligned with the coaxial terminals with which it is engaged. Furthermore, it will be noted that when the ball 17 enters channel 21, it does so moving out along the length of the channel, and therefore with no sudden shock, and it leaves in the same manner. During the pe riod of rotation represented by FIGS. 3B-3F, the drum is sped up and slowed down with essentially a simple harmonic motion, and therefore with a minimum of Shock of sudden acceleration. This is of importance in the case where it is desired to rapidly Shift from one attenuator to any other selected attenuator, which may involve rotating the drum through practically a full revolution, in the case where a uni-directional motor drive is employed, which is the usual situation.

FIG. 4 shows a motor-driven arrangement for the attenuator, the motor 26 being usually actuated by a selector circut, not shown because this is not part of the pres ent invention but which is a well-known arrangement, whereby a remote circut selector causes the motor to drive for a sufiicient distance to put any selected attenua- 3 tor into the circuit. In some cases, it is desired to do this within a fraction of a second, and the motor must therefore be driven at high speed. The present attenuator is well adapted to this use, due to the above-described characteristics, since it can be driven at very high speed without producing excessive shocks or strains in the system.

It will be noted that all the coacting elements of the above-described drive can be made by simple machining Operations using standard equipment.

F IGS. 5 and 6 show a linear step attenuatior Operating on the same principle as FIGS. 1-4, except that the drum 3 is straightened out to form a linear element 3' which slides back and forth as knob 14' is turned. Corresponding elements are identified by the same reference numbers as in FIGIS': 1-4, with a prime added, and except for the linear motion, the action is the same as described above.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in Construction and arrangement within the scope of my invention as defined in the appended claims.

I claim:

1. A stepping device for coaXial conductor attenuating circuits comprising (a) a rotatable cylindrical drum having equally spaced recesses for holding attenuators,

(b) a yoke mounting said drum for rotation about its central axis,

(c) coaXial terminal means supoprted by said yoke in circuit conductive alignment with an attenuator mounted in one of said recesses,

(d) means for rotationally stepping said drum to successively and selectively present other attenuators respectively held in recesses into connective alignment with said terminal means,

(e) said last means (d) comprising a rotary drive shaft mounted at right angles to the axis of said drum,

(f) a drive boss fixed to said shaft at an end thereof adjacent to the surface of said drum, said boss being radially spaced from the axis of said shaft and oriented for rotation in a plane perpendicular to the shaft and beyond its end,

(g) a stop boss fixed to said shaft in the plane of rotation of said drive boss and having a substantially semi-cylindrical stop surface diametrically opposed to said drive boss and coaxial with said shaft,

(h) an annular raised band of the surface of said drum having a series of spaced longitudinal Channels lying parallel to the axis of the drum and cooperating With said drive boss during substantially one-half cycle of rotation of said drive shaft to move said drum one step during said one-half cycle, said channels being spaced a distance corresponding to twice the radial 4- dstance of said drive boss from its center of rotation,

(i) said annular band having circular cut-out portions between said channels to snugly receive said stop boss and cooperate with its cylindrical surface during the other half cycle of rotation of the drive shaft so as to prevent rotary movement of said drum during said other half cycle,

(j) said terminal means being positioned so as to be in conductive contact with an attenuator held by the drum when the stop channel is engaged at one of said cut-out portions.

2. The invention according to claim 1, said spaced recesses being separated by such a distance that attenuators held therein are sucessively presented into Contacting position with said terminals during successive full revolutions of said shaft.

3. The invention accordin to claim 1, said drive boss being in the form of a ball having a diameter slightly smaller than the width of an engaged channel.

4. The invention according to claim 1, and a series of graded attenuators held in said spaced recesses of the drum for successive engagement of said terminals.

References Cited UNITED STATES PATENTS 2,427,745 9/1947 Roger-Petit 74-84 2,613,321 10/1952 Howard 325-464 3,046,499 7/1962 Waldick 333-81X 3,219,953 11/1965 Schwartz 333-81 3,248,953 5/ 1966 Holper et al. 74 10.l5 3,299,373 1/1967 Conney 333-81 2,44S,793 7/1948 Marchand 333-7 FOREIGN PATENTS 594,142 11/ 1947 Great Britain 74-436 OTHER REFERENCES Geneva Design Permits Fast Index With Pause for Position Selection, Design News, July 1, 1956, Rogers Publishing Company, Englewood, Colo., pp. 26-27.

The Elements of Mechanics and Mechanisms, Camm George Newnes Limited (Scientific Library, June 3, 1957), TJ145, pp 127, 128, and 134.

HERMAN KARL SAALBACH, Primary Examiner M. NUSSBAUM, Assistant Examiner U.S. Cl. X.R. 333-7, 97

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