Waveguide connection structure, determination method thereof, manufacturing method thereof, and waveguide switch using same

1. A waveguide connection structure comprising:

two waveguides having end faces each of which is formed with at least one waveguide path, the end faces facing each other in parallel with a predetermined gap, wherein

a choke groove having a depth corresponding to ¼ of a guide wavelength corresponding to a leakage prevention target frequency is provided at the end face of at least one of the two waveguides, in a band-shaped region surrounding an opening of a rectangle of the at least one waveguide path,

the band-shaped region is a region whose center is a center of the rectangle, and which is bounded by an inner ellipse and an outer ellipse whose major axis direction is parallel to a longer side of the rectangle,

a minor radius of the inner ellipse corresponds to ¼ of the guide wavelength,

a minor radius of the outer ellipse is longer than the minor radius of the inner ellipse by a length corresponding to ¼ of the guide wavelength, and

the choke groove includes two groove portions that are in contact with the inner ellipse and the outer ellipse and are located on the longer side of the rectangle, in the band-shaped region.

2. The waveguide connection structure according to claim 1 , wherein

the choke groove further includes two groove portions that are in contact with the inner ellipse and the outer ellipse and are located on a shorter side of the rectangle, in the band-shaped region, and

the four groove portions are separated from each another by four non-groove portions along a diagonal direction of the rectangle in the band-shaped region.

3. A determination method of a waveguide connection structure in which end faces of two waveguides respectively formed with at least one waveguide path face each other in parallel with a predetermined gap, a choke groove having a depth corresponding to ¼ of a guide wavelength corresponding to a leakage prevention target frequency is provided at the end face of at least one of the two waveguides, in a band-shaped region surrounding an opening of a rectangle of the at least one waveguide path, the band-shaped region is a region whose center is a center of the rectangle, and which is bounded by an inner ellipse and an outer ellipse whose major axis direction is parallel to a longer side of the rectangle, a minor r radius of the inner ellipse corresponds to ¼ of the guide wavelength, a minor radius of the outer ellipse is longer than the minor radius of the inner ellipse by a length corresponding to ¼ of the guide wavelength, and the choke groove includes two groove portions that are in contact with the inner ellipse and the outer ellipse and are located on the longer side of the rectangle, in the band-shaped region, the determination method comprising:

an electromagnetic field analysis step of, by using, as an analysis model, an analysis waveguide connection structure in which end faces of two analysis waveguides, which respectively have waveguide paths of the same shape as the waveguide paths and are not formed with choke grooves, face each other in parallel with a predetermined gap, when an electromagnetic wave of the leakage prevention target frequency propagates from one to the other of the two analysis waveguides which are not formed with the choke grooves, acquiring a shape of an equiphase surface of electromagnetic waves leaking from the predetermined gap by electromagnetic field analysis;

an ellipse shape acquisition step of acquiring a minor radius and a major radius of an equiphase surface separated by a distance corresponding to ¼ of the guide wavelength in a direction perpendicular to the longer side of the rectangle from the center of the rectangle, among the equiphase surfaces acquired in the electromagnetic field analysis step;

an inner ellipse shape determination step of determining the minor radius and the major radius of the equiphase surface acquired in the ellipse shape acquisition step as the minor radius and a major radius of the inner ellipse; and

an outer ellipse shape determination step of determining values obtained by respectively adding a distance corresponding to ¼ of the guide wavelength to the minor radius and the major radius of the inner ellipse determined in the inner ellipse shape determination step as the minor radius and a major radius of the outer ellipse.

4. A manufacturing method of a waveguide connection structure in which end faces of two waveguides respectively formed with at least one waveguide path face each other in parallel with a predetermined gap, a choke groove having a depth corresponding to ¼ of a guide wavelength corresponding to a leakage prevention target frequency is provided at the end face of at least one of the two waveguides, in a band-shaped region surrounding an opening of a rectangle of the at least one waveguide path, the band-shaped region is a region whose center is a center of the rectangle, and which is bounded by an inner ellipse and an outer ellipse whose major axis direction is parallel to a longer side of the rectangle, a minor radius of the inner ellipse corresponds to ¼ of the guide wavelength, a minor radius of the outer ellipse is longer than the minor radius of the inner ellipse by a length corresponding to ¼ of the guide wavelength, and the choke groove includes two groove portions that are in contact with the inner ellipse and the outer ellipse and are located on the longer side of the rectangle, in the band-shaped region, the manufacturing method comprising:

an electromagnetic field analysis step of, by using, as an analysis model, an analysis waveguide connection structure in which end faces of two analysis waveguides, which respectively have waveguide paths of the same shape as the waveguide paths and are not formed with choke grooves, face each other in parallel with a predetermined gap, when an electromagnetic wave of the leakage prevention target frequency propagates from one to the other of the two analysis waveguides which are not formed with the choke grooves, acquiring a shape of an equiphase surface of electromagnetic waves leaking from the predetermined gap by electromagnetic field analysis;

an ellipse shape acquisition step of acquiring a minor radius and a major radius of an equiphase surface separated by a distance corresponding to ¼ of the guide wavelength in a direction perpendicular to the longer side of the rectangle from the center of the rectangle, among the equiphase surfaces acquired in the electromagnetic field analysis step;

an inner ellipse shape determination step of determining the minor radius and the major radius of the equiphase surface acquired in the ellipse shape acquisition step as the minor radius and a major radius of the inner ellipse;

an outer ellipse shape determination step of determining values obtained by respectively adding a distance corresponding to ¼ of the guide wavelength to the minor radius and the major radius of the inner ellipse determined in the inner ellipse shape determination step as the minor radius and a major radius of the outer ellipse;

a choke groove formation step of forming the choke groove in the band-shaped region defined by the minor radii and the major radii of the inner ellipse and the outer ellipse determined in the inner ellipse shape determination step and the outer ellipse shape determination step; and

a waveguide arrangement step of arranging the two waveguides such that the end faces of the two waveguides face each other in parallel with the predetermined gap.

5. A waveguide switch comprising:

a base portion;

a first fixed waveguide block that is fixed to the base portion, and in which at least one waveguide path surrounded by a metal wall is formed penetrating from a first end face to a second end face;

a second fixed waveguide block that is fixed to the base portion and has a third end face parallel to the second end face of the first fixed waveguide block, and in which at least one waveguide path surrounded by a metal wall is formed penetrating from the third end face to a fourth end face;

a movable waveguide block which has a fifth end face facing the second end face of the first fixed waveguide block with a predetermined gap in parallel and a sixth end face facing the third end face of the second fixed waveguide block with a predetermined gap in parallel, in which a plurality of waveguide paths surrounded by metal walls are formed penetrating from the fifth end face to the sixth end face, and which is supported by the base portion so as to be slidable parallel to the second end face of the first fixed waveguide block and the third end face of the second fixed waveguide block; and

a driving device that is provided on the base portion and slides the movable waveguide block, wherein

the movable waveguide block is slid with respect to the first fixed waveguide block and the second fixed waveguide block, and any one of the plurality of waveguide paths of the movable waveguide block is selectively connected to between any one of the at least one waveguide path of the first fixed waveguide block and any one of the at least one waveguide path of the second fixed waveguide block, in different plurality of positions,

a choke groove having a depth corresponding to ¼ of a guide wavelength corresponding to a leakage prevention target frequency is provided, in a band-shaped region surrounding at least one of an opening of the at least one waveguide path on a second end face side of the first fixed waveguide block, an opening of the at least one waveguide path on a third end face side of the second fixed waveguide block, and openings of the plurality of waveguide paths on a fifth end face side and a sixth end face side of the movable waveguide block,

the band-shaped region is a region whose center is a center of a rectangle, and which is bounded by an inner ellipse and an outer ellipse whose major axis direction is parallel to a longer side of the rectangle,

a minor radius of the inner ellipse corresponds to ¼ of the guide wavelength,

a minor radius of the outer ellipse is longer than the minor radius of the inner ellipse by a length corresponding to ¼ of the guide wavelength, and

the choke groove includes two groove portions that are in contact with the inner ellipse and the outer ellipse and are located on the longer side of the rectangle, in the band-shaped region.