US3105206A

US3105206A - Microwave circulator

Info

Publication number: US3105206A
Application number: US190105A
Authority: US
Inventors: Clebert J Bosset; Frank J Hughes
Original assignee: Sylvania Electric Products Inc
Current assignee: GTE Sylvania Inc
Priority date: 1962-04-25
Filing date: 1962-04-25
Publication date: 1963-09-24
Anticipated expiration: 1980-09-24

Description

n /A//// a 1 a E G J T 7 c3 v1 (y 2... xv l z v F H a a 33 u P 24, 1953 I c. J. BOSSET ETAL MICROWAVE CIRCULATOR Filed April 25, 1962 INVENTORS CLEBERT J. BOSSET FRANK J. U HES ATTORNEY United States Patent 3,105,206 MICRQWAVE (JIRCULATOR Clebert J. Bosset, Newark, and Frank J. Hughes, Anahelm, Calif., assignors to Sylvwia Electric Products Inc a corporation of Delaware Filed Apr. 25, 1962, der. No. 190,105 7 Claims. (Cl. 333--1.1)

This invention relates to improvements in a microwave circulator construction of the type described and claimed in application S.N. 59,579, file-d September 39, 1960, entitled Broadband Nonreciprocal Microwave Transmission Device, now Patent No. 3,070,760, and assigned to the :assignee of this application.

The T circulator described in the above application comprises a rectangular wave-guide T with three arms, and a ferrite post or rod in the junction of the arms and extending transversely of the narrow dimension of the T from one broad wall to the other. In assembling the circulator, it is necessary to make incremental adjustments of the position of the post Within the junction to optimize performmice of the ci-rculator. Current practice is to secure the post to the :broad walls of the junction with a Weak adhesive film which can be broken to permit positioned adjustment, if necessary, and yet is strong enough to hold the post in place in event no further adjustments are necessary. It follows that the adhesive bond is limited in strength thus permitting the post to loosen under severe vibration or impact.

In accordance with our invention, the post is secured in place by a constricting force applied through the Walls of the waveguide so as to frictionally hold the ends of the post. The thickness of the portion of at least one of the broad Walls of the junction which abuts the ferrite post is reduced so as to be flexible like a diaphragm. One of the permanent magnets is pressed against the outside of the reduced wall by means of a screw to flex the wall inwardly against the end of the post and frictionally lock it in place within the junction. If subsequent adjustments of position of the post are necessary, release of the screw pressure loosens the grip and permits the adjustment and relocating of the post.

A general object of this invention is the provision of a simple system for releasably locating a ferrite post in a circulator junction without the use of adhesives.

These and other objects of the invention will become apparent from the following description of the preferred embodiment thereof, reference being had to the accompanying drawings in which.

FIGURE 1 is a perspective view of a three-port T circulator partially cut away to illustrate the position of the ferrite post relative to the walls of the T;

FIGURE 2 is a partial section view taken along line 22 of FIGURE 1 illustrating the support arrangement of the post and biasing magnets within the T;

FIGURE 3 is a partial section View taken in the dh'ection of line 33 of FIGURE 1 omitting portions of the arms of the T; and

FIGURE 4 is an enlarged view of a portion of the support arrangement shown in FIGURE 2 illustrating the support of the biasing magnet relative to the Waveguide wall of the T.

Referring now to the drawings, a preferred embodiment of the invention is illustrated in FIGURE 1 as a standard H-plane rectangular waveguide T 16 comprising three rectangular waveguide arms l1, l2, and 13 having end openings or

ports

14, 15, and 16, respectively, facing outwardly from junction 17. At the outer ends of the three arms are mounting

flanges

18, 19, and 20, respectively, for mechanically connecting the T section 19 to associated microwave circuits.

Element 21 which may be gyrom-agnetic material, such as ferrite, in the form of a cylindrical post or rod, is mounted at the junction of the arms ll, 12, and 13 between the top and bottom

broad walls

23 and 24, see FIGURE 2, and axially aligned with

disc magnets

32 and 33. The rod is located preferably midway between the

side walls

29 and 30, see FIGURE 3, normal to the broad walls and at a distance C from side wall 26. Dimension C varies between one-fourth to one-half the long crosssection dimension A for the optimum location of the post. The height of the rod is slightly less than the height dimension B of the waveguide so that the rod has a slip fit with the inner surfaces of the relaxed broad walls. In order to lock the post between the walls, portions of the broad Walls at the junction are flexed inwardly 'by a constricting force to frietionally hold the ends of the post in place as explained hereinafter.

Disc magnets

32 and 33 are located exteriorly of the junction and each has a side surface 36 and

end surfaces

37 and 37a. These magnets are mounted within substantially identical

cylindrical supports

34 and 35 in additive polarity so that

end surfaces

37 and 37a are north and south magnetic poles, respectively, and produce a constant unidirectional magnetic field in rod 21 parallel to its axis 28. In accordance with the principle of the circulation as explained in the aforementioned patent application, the magnitude of the field is greater than that required for saturation of the ferrite post but is less than that required for ferromagnetic resonance, i.e., less than a field which causes precession of electrons of the ferrite about the axis of magnetic field at a frequency equal to that of the propagating electromagnetic Wave.

Since the upper and lower magnet assemblies are substantially identical, only the upper assembly Will be described in detail below.

Referring now to FIGURES 3 and 4, each of waveguide

broad walls

23 and 24 is formed with a cylindrical recess 38 in alignment with the central part of the junction, and an annular recess 39 at the periphery of recess 38. The waveguide wall portion 23a at the bottom of recess 38 is substantially thinner than the rest of the Wall and therefore is capable of readily being flexed or bowed inwardly of the junction and of returning to its original position. The diameter of recess 38 is substantially larger than that of the ferrite post.

Cylindrical support 34 has an outside diameter substantially the same as or slightly greater than the diameter of annular recess 39 and is press fitted into and thereafter brazed in the latter with the longitudinal axis of the sup port normal to broad wall 23. The support is threaded interiorly throughout its length, minimum diameter of the thread teeth 42 being about the same as or slightly greater than the outside diameter of cylindrical magnet 32. The teeth therefore prevent substantial lateral movement of the magnet while permitting it to move axially within the support in the direction of the arrow 47 in FIGURE 4.

A cap 52, see FIGURE 2, threaded into the support abuts the outer end 37a of the magnet and is adapted to force the magnet inwardly against flexible Wall portion 23a. The diameter of the magnet, being less than that of recess 38, transmits the axial force of the cap against the portion of the thin wall 23a that is spaced inwardly from peripheral face 44 defining the recess. The thin wall section therefore bows inwardly, as shown in FIG- URE 4, being hinged to the thicker wall section at face 44 in the manner of a diaphragm.

A three-port H-plane T-junction circulator with a ferrite post support arrangement at the junction of the arms and having the following dimensions and characteristics has been constructed and successfully operated:

Waveguide:

Dimension A inches 1.000 Dimension B do 0.400 Dimension C do 0.375 Thickness of

walls

23 and 24 do 0.050 Thickness of reduced walls 23a do 0.025 Rod 21:

Material Magnesium-manganese ferrite. Diameter inch 0.281 Length do 0.400 Frequency range gc 8.7-8.8 Isolation:

Minimum db 90 Maximum db 100 insertion loss db 2 VSWR 1.10 Magnets 32 and 33:

Diameter inches 0.750 Height do 0.50 Magnetic field intensity gausses 600 Supports 34 and 35:

Outside diameter inches 1.0 Inside diameter do 0.750 Thread pitch and series NEF 20 Recesses 33:

Diameter inches 0.813 Height do 0.025 Caps 52:

Outside diameter -inch Thread series NEF 20 It should be understood that this invention in its broadest aspects is not limited to the specific embodiment described above. For example, adequate grippage of the post may be provided using a single recess 38 adjacent to the ferrite post 21 instead of a pair as shown in FIGURE 2. The appended claims are intended to include all changes and modifications within the spirit and scope of the invention.

We claim:

1. A microwave circulator comprising three sections of rectangular waveguide having broad and narrow walls directly connected in the form of a T-junction with the H-planes of the section parallel, said broad walls having exterior cylindrical recesses formed therein whereby said broad walls are reduced forming thin wall portions at the extremities of the recesses,

a ferrite post located within said sections adjacent to said recesses and extending parallel with the narrow Walls thereof,

permanent disc magnets mounted externally of said junction adjacent to said post in additive polarity producing a steady magnetic field therein with portions of said magnets located within said recesses,

and support means for securing said post relative to said broad walls and said magnets relative to said post comprising cylindrical support members attached to the broad walls of said sections enclosing said magnets and recesses, and having threaded interior surfaces in contact with said magnets; and cap members having threaded surfaces engageable with the threads of said support members and end surfaces in contact with said magnets whereby a constricting force is provided, said force being transmitted through said magnets to said thin wall portions of said broad walls thereby causing elongation thereof to secure said post relative to said broad walls.

2. A microwave circulator comprising three sections of rectangular waveguide having broad and narrow walls and directly connected in the form of a T-junction with the H-planes of the section parallel, said broad walls having exterior recesses formed therein whereby said broad walls are reduced at the extremities of the recesses thereby forming reduced wall portions,

a ferrite post located within said sections at said junction adjacent to said recesses and extending parallel with the narrow walls thereof,

permanent magnets mounted externally of said junction adjacent to said post producing a steady magnetic field therein, said magnets having portions located within said recesses,

and support means for securing said post relative to said broad walls and said magnets relative to said post comprising support members in contact with the broad walls of said sections enclosing said magnets,

and means for providing a constricting force to said reduced portions of said broad Walls, said force being transmitted through said magnets to said reduced portions thereby causing elongation thereof to secure said post relative to the broad walls.

3. A microwave circulator comprising sections of waveguide having 'walls directly connected in the form of a T-junction, said walls having exterior recesses formed therein,

a ferrite post located within said sections adjacent to said recesses, I

magnets mounted to said Wal is externally of said junction adjacent to said post producing a magnetic field therein,

and means for securing said post relative to said broad walls and said magnets relative to said post comprising support members in contact with the walls of said sections and enclosing said magnets, and means for providing a constricting force to portions of said walls adjacent said post, said force being transmitted through said magnets to said portions thereby causing elongation to secure said post relative said walls.

4. A microwave circulator compnising sections of waveguide having walls directly connected in the form of a T-junction, said walls having exterior recesses formed therein,

a ferrite post located within said sections adjacent to said recesses,

magnets mounted to said walls externally of said junction adjacent to said post producing a magnetic field therein, said magnets having portions located within said recesses,

and support means for securing said post relative to said broad Walls and said magnets relative to said post.

5. Support means for a ferrite post within a microwave device comprising a Waveguide enclosing said post having a longitudinal axis and a recess formed in an exterior surface of said waveguide adjacent to said post, said recess having an axis normal to said waveguide axis,

support members connected to said waveguide adjacent to said post having vertical axes normal to said waveguide axis, with the axis of one of said members being collinear with said axis of said recess,

first and second magnets located within said support members providing a magnetic field in said post with a portion of said first magnet being located in said recess,

and means for providing a constricting force to a portion of said waveguide adjacent to said recess, said force being transmitted through said first magnet to said portion to cause elongation thereof thereby securing the ends of the post relative to the waveguide.

6. A circulator comprising three rectangular waveguides connected together at a junction with the broad walls of hte wavegiides and of the junction lying in two parallel planes, respectively,

a ferrite post mounted within said junction normal to said reduced wall portion inwardly of said junction the broad walls thereof and with the ends of the whereby said post is compressively frictionally post lightly engaging the inner surfaces, respectively, gripped by the broad walls of the junction, of the junction broad walls, at least one of said juncand means for magnetically biasing said ferrite post. tion broad walls having the post engaging portion 5 7. The circulator according to claim 6 in which said With a reduced Wall thickness whereby said wall last named means comprises at least one permanent magportion may be flexed inwardly and outwardly of net engaging said reduced wall portion externally of said said junction, junction.

means for releasably applying a flexing force against NO references Cited-

Claims

6. A CIRCULATOR COMPRISING THREE RECTANGULAR WAVEGUIDES CONNECTED TOGETHER AT A JUNCTION WITH THE BROAD WALLS OF THE WAVEGUIDES AND OF THE JUNCTION LYING IN TWO PARALLEL PLANES, RESPECTIVELY, A FERRITE POST MOUNTED WITHIN SAID JUNCTION NORMAL TO THE BROAD WALLS THEREOF AND WITH THE ENDS OF THE POST LIGHTLY ENGAGING THE INNER SURFACES, RESPECTIVELY, OF THE JUNCTION BROAD WALLS, AT LEAST ONE OF SAID JUNCTION BROAD WALLS HAVING THE POST ENGAGING PORTION WITH A REDUCED WALL THICKNESS WHEREBY SAID WALL PORTION MAY BE FLEXED INWARDLY AND OUTWARDLY OF SAID JUNCTION, MEANS FOR RELEASABLY APPLYING A FLEXING FORCE AGAINST SAID REDUCED WALL PORTION INWARDLY OF SAID JUNCTION WHEREBY SAID POST IS COMPRESSIVELY FRICTIONALLY GRIPPED BY THE BROAD WALLS OF THE JUNCTION, AND MEANS FOR MAGNETICALLY BIASING SAID FERRITE POST.