US 3671801 A
A magnetron is rapidly tuned over a wide bandwidth by inserting and withdrawing a conductive tuning element in an anode cavity. The conductive element is mounted on a plate which is moved in increments by a plurality of solenoids. A stop is mounted on the solenoids and each solenoid when actuated pulls the plate an incremental distance. The plate, when actuated by a single solenoid slides along the other solenoid rods in the solenoid array. A spring pushes the plate against the force of the solenoids and returns the plate to position of maximum element insertion, when the solenoids are de-energized.
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Description (OCR text may contain errors)
United States Patent Masek  MAGNETRON RAPID FREQUENCY CHANGER  Inventor: Roland C. Masek, Sykesville, Md.
 Assignee: The United States of America as represented by the Secretary of the Navy 22 Filed: March 25,1971 21 Appl.No.: 128,103
 US. Cl ..3l5/39.55, 315/3959, 315/3961,
331/90  Int. Cl. ..l-l0lj 25/50  Field olSearch ..3l5/39.55, 39.59, 38.61; 331/90  References Cited UNITED STATES PATENTS 2,589,885 3/1952 Sonkin ....3l5/39.59 2,801,367 7/1957 Spencer... ...3l5/39.61 2,508,576 5/l950 Kusck ....3l5/39.6l
l I I l I I I l L 1451 June 20, 1972 3,027,488 3/1962 Wmsor ..315/39.6l 3,187,220 6/1965 Dench 315/3961 3,297,909 l/l967 Foreman et a1. ...3l5/39.6l 3,599,035 8/1971 Fren'chs ..3 15/3959 Primary Examiner-Herman Karl Saalbach Assistant Examiner-Saxfield Chatmon, .lr. Attorney-R. S. Sciascia and Q. E. Hodges [5 7] v ABSTRACT A magnetron is-rapidly tuned over a wide bandwidth by insening and withdrawing a conductive tuning element in an anode cavity. The conductive element is mounted on a plate which is moved in increments by a plurality of solenoids. A stop is mounted on the solenoids and each solenoid when actuated pulls the plate an incremental distance. The plate, when actu ated by a single solenoid slides along the other solenoid rods in the solenoid array. A spring pushes the plate against the force of the solenoids and returns the plate to position of maximum element insertion, when the-solenoids are de-energized.
6 Claims, 3 Drawing figures Pmmimuuzo I972 3.671.801
sum 1 or z INVENTOR. ROLAND 6. MASEK FIG. 2. BY
A 7' TOR/VE Y P'A'TE'N TEDJHMO I972 SHEET 2 OF 2 C. B A
F 6 3 ROLAND C. MASEK I ATTORNEY MAGNE'IRON RAPID FREQUENCY CHANGER This invention relates to magnetrons and more particularly to a magnetron structure having electrically actuated parts for tuning the magnetron rapidly over a wide range of frequencies. I
In some applications of magnetrons, it is required to rapidly tune the magnetron over a wide frequency band. In the past, tuning of the magnetron has been accomplished in a variety of ways. For example, the pulling effect" is all often employed to tune a magnetron over a fraction of a percent bandwidth by mismatching the load coupled to the output of a magnetron. The pushing effect" is also employed by varying anode voltage, although generally this effect is undesirable and is eliminated whenever possible even through tuning over a somewhat wider bandwidth (about 1 percent) can be obtained.
' therein. Tuning rod is mounted on plate 17. Plate 17 is Recently, conductive tuning elements have been employed in magnetrons, which are movable in and out of the anode cavity spaces, to accomplish tuning. A cylindrical element is usually employed which has the same general conformation as the cavity but is somewhat smaller so that it may fit within the cavity without touching the sides. The magnetron tube is sometimes equipped with a diaphragm arrangement which can be flexed externally to thereby move the plunges in andout of the cavities, tuning the magnetron over a relatively wide frequency band. For example, in some structures of this type, 50 percent bandwidth tuning has been accomplished. However, such plunger tuned magnetrons have not been readily tuned at high rates but are usually adjusted manually by an operator to produce a given frequency and once thisfrequency is established it is not changed again for sometime.
SUMMARY OF THE INVENTION In accordance with the present invention a tunable element is positioned within a cavity of a magnetron anode. The tuning element is attached to a plate, the plate being mounted on a number of solenoid rods. The solenoid rods are each of a unique length and each rod has a stop on its end. All rods are of a finite length and each rod is moved by its respective solenoid, a finite distance.
At the position of maximum tuning element insertion, the plate is held against one of the solenoid stops by a spring. As the first solenoid is actuated, the force of the solenoid applied to the stop lifts the plate and the element away from the magnetron anode, the plate sliding along the other solenoid rods inserted through the plate. When it is desired to remove the tuning element, an additional increment from the anode cavity, a second solenoid is operated applying a force to the plate through its respective stop element and sliding the plate along the inactivated solenoids.
Accordingly, it is one object of this invention to provide a magnetron with a capability for rapid tuning over a wide frequency band.
Other features and object of the invention will be more apparent from the following specific description taken in conjunction with the drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, the anode block 10, within a magnetron is shown as having cavity resonators 11, one of the cavity resonators designated 11', having a coupling loop 13inserted therein for extracting RF energy.
The block structure shown in FIG. 1, shown in section in shown as having a plurality of holes 19, 21 and 23, and in each hole a solenoid rod 25, 27 and 29, respectively, is slidely fitted. Atthe end of each solenoid rod is a fixed stop, stop 31 on rod 25, stop 33 on rod 27, and stop 35 on rod 29. A solenoid coil is mounted on each solenoid rod, coil 43 on rod 25, coil 39 on rod 27 and coil 41 on rod 29.
A spring means 38, has a force in the direction of arrow 37 on surface 39 of plate 17, forcing plate 17 down against stop 33 of solenoid rod 27.
Referring now to FIG. 3, a side view along sections 3-3 of FIG. 2, is shown and wherein like numerals designate like and similarly operating parts. In FIG. 3, cavity resonator 11' is shown partly in phantom. Conductive tuning element 15 is extended down in the cavity 11 and can be partially seen through slot 14in block 10, the hidden portion of tuning element 15 within cavity resonator 11' being shown in phantom. The tuning element as shown in FIG. 2 and FIG. 3, is at its position of maximum insertion into cavity 11' and under spring force 37 is held in this position by stop 33 on rod 27.
OPERATION OF THE DEVICE Operation of the device will now be described with reference to the solenoid actuators solenoid 39 on rod 27, solenoids 41 on rod 29 and solenoid 43Von rod 25. Actuation of these solenoids causes its respective rod to move in the direction as shown by arrow 45 in FIG. 3. Under spring force 37 the plate 17 is held against stop 33 on rod 27 and the tuning element is at its maximum insertion in cavity 1 1 To change the frequency of this device a first increment solenoid 43 is energized displacing solenoid rod 25 in the upward and vertical direction 45 and forcing stop 31 on rod 25 against plate 17.'The continued upward movement of rod 25 to its point of maximum vertical displacement forces stop 31 to ,lift the plate 17 through a distance A and holds the plate at line 47.
As can be seen and is well known in the art, the retraction of tuning element 15 of cavity 1 1 for the distance A changes the frequency of the magnetron. In moving from its fully inserted position shown in FIG. 3, upward to level 47, the plate 17 slides along rod 27 and rod 29.
To change the frequency of the magnetron a second increment, solenoid 41 is actuated displacing rod 29 in a vertically upward direction 45, and bringing stop 35 against plate 17. As rod 25 continues its upward travel to its point of maximum vertical displacement, it drives plate 17 a distance B, from level 47 to lever 49, sliding plate 17 along solenoid rods 25 and 27. At level 49 plate 17 has moved an increment B or a total incremental distance A B, by the operation of solenoids 43 and 41.
To change the frequency of the magnetron a third increment, solenoid 39 is operated drawing solenoid rod 27 in the upward vertical direction 45 and forcing plate 17, by stop 31, through the distance C, between level 49 and 51. In this position, plate 17 has traveled a total distance of A B C. As is well known to those skilled in the art, the frequency of the magnetron will be unique for each of the levels 47, 49 and 51.
In a similar manner the frequency of the magnetron may be changed by de-energizlng sequentially each of the solenoids 39, 41 and 43. This may be done as follows: To drive plate 17 from level 51 to level 49, solenoid 39 would be de-energized and plate 17 under spring force 37 would be forced down against stop 35 on solenoid rod 29, stop 35 being at level approximately at level 49. Similarly to change the magnetron frequency to that when the plate 17 is at level 47, solenoid 41 would be de-energized and spring force 37 would similarly force plate 17 down against stop 31 of solenoid rod 25 to level 47. Finally, to bring the operating frequency of the magnetron back to its point where the tuning element 15 has its maximum insertion into cavity 11', solenoid 43 would be de-energized and spring force 37 would similarly force plate 17 down FIG. 2, with the cylindrically shaped tuning rod 15 inserted against stop 33 of tuning element 27.
By operating solenoids 43, 41 and 39 in sequence, or by operating each of the solenoids individually, the frequency of the magnetron can be rapidly changed over wide band limits.
Although the preferred embodiment shows solenoid actuated rods, the invention is not limited by the specific type of actuator used. Obviously many other various means of actuation could be used such as hydraulic, or pneumatic or any other actuator which permits a mechanical force to be rapidly applied to the rods 25, 27 and 29.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
What is claimed is:
l. A magnetron rapid frequency changer, comprising:
a tuning element for insertion into a magnetron cavity resonator;
said tuning rod being afiixed to said plate;
said plate having a plurality of holes;
a plurality of rods;
each of said rods being inserted through a respective hole in said plate;
said plate being slidably mounted on said rods;
each said rod having a stop mounted on its end; means biasing said plate toward said stops; and
means to move each of said rods through its said respective holes thereby forcing its respective stop against said plate, and moving said plate.
2. The apparatus of claim 1, wherein:
each of said stop is disposed on the same side of said plate;
each said stop being mounted on its respective rod at a unique distance from said plate, when said tuning element is at its point of maximum insertion.
3. The apparatus of claim 2, wherein:
said means to move separately moves each rod through its respective hole a discrete distance; and
including a spring to force said plate towards said stops.
4. The apparatus of claim 3, wherein:
said plurality of rods includes first, second and third rods;
said spring forcing said plate against the stop on said first rod;
said means to move displacing said second rod a finite distance to slide said plate along said first and third rods, against the force of said spring, moving said tuning element an increment away from said cavity;
said means to move displacing said third rod a finite distance to slide said plate along said first and second rods against the force of said spring and moving said tuning element an increment away from said cavity; and
said means to move displacing said first rod a finite distance to slide said plate along said second and third rods and against the force of said spring, moving said tuning element an increment away from said cavity.
5. The apparatus of claim 1, wherein:
said means to move is a plurality of solenoids; and
each said rod is a solenoid rod, inserted within a respective solenoid.
6. The apparatus of claim 4, wherein:
said means to move is a plurality of solenoids; and
each said rod is a solenoid rod, inserted within a respective solenoid.
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