POLARISATION-PRESERVING FILTER FOR A DUAL-POLARISED WAVEGUIDE

1 . A polarisation-preserving filter for a dual-polarised waveguide with a basic body that is circular in cross section, the filter comprising a plurality of nubs arranged in an interior of the basic body, wherein the nubs are grouped in several rings, wherein a first predetermined frequency band can be transmitted unobstructed and transmission of a second predetermined frequency band can be blocked.

2 . The filter of claim 1 , wherein the nubs have one or more of the following structural forms:

cuboid;

cylinder;

hemisphere;

hemiellipsoid;

prism;

cone or truncated cone;

pyramid or truncated pyramid;

combinations of different geometries.

3 . The filter of claim 1 , wherein the number of nubs per ring is identical.

4 . The filter of claim 3 , wherein adjacent nubs of the rings are arranged on an axis parallel to the direction of the axial extension of the basic body.

5 . The filter of claim 1 , wherein the number of nubs per ring is different.

6 . The filter of claim 1 , wherein the dimensions of the nubs of a ring are identical in respect of at least one of height and lateral extension.

7 . The filter of claim 1 , wherein the dimensions of the nubs of a ring are different in respect of at least one of height and lateral extension.

8 . The filter of claim 1 , wherein the nubs are distributed evenly over the circumference of a ring.

9 . The filter of claim 1 , wherein the nubs are distributed differently over the circumference of a ring, so that the spacings between two nubs have different values.

10 . The filter of claim 1 , wherein the spacings of the rings are identical in an axial direction of the basic body.

11 . The filter of claim 1 , wherein the spacings of the rings are different in an axial direction of the basic body.